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102 Cards in this Set

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a) Who provided a vast amount of convincing evidence in supptort of evolution, or the change in population over time?
b) how?
a) Charles Darwin
b) when he published' "On the Origin of Species", in 1859.
a) what is a population
b) what is the genetic make-up of a population
a) a population is the unit of evolution, so pop. evolve, not individual organisms.
b) the genetic make-up of a pop is described as the genotypic and allele freq's of the pop
what is the mathematical model or description of pop genetics that shows us that the genetic structure of a pop is not altered by the process of sexual reprod. and heredity themselves?
The Hardy Weinberg Rule
what does the Hardy Weinberg Rule state?
It states that the allele freq of a pop will remain constant regardless of the starting freq, and the genotypic freq will always reach equilibrium and remain constant after only one generation of random mating.
What 5 conditions need to be met for the Hardy Weinberg to hold true?
2) Mating is completely random
3) There is no migration of individuals on the pop. i.e., all genotypes have equal chances of reproductive success
** this is a model to show how gene freq do not change and evolution doesn't occur, by investigating the impacts of mutation, migration, pop size, nonrandom mating and natural selection as evolutionary effects
a) What is the HW equilibrium?
b)How do youcalculate the Genotypic Freq?
a) When assuming a pop has only two alleles, A and a. If A is dominant, then its freq is equal to p, while if a is recessive, then its freq is equal to q. Then is follows that: p + q = 1

b) (p+q)^2 =
p^2 + 2pq + q^2 = 1
ASK Prof. (How many times do I repeat these steps)

STEPS to testing the HW Rule
1) If your group were to be assigned the freq's:
0.2 AA
0.7 Aa
0.1 aa
you need to first know your:
Observed Initial (this is genrally assigned) Genotypic Freq's:
0.55 = AA
0.25 = Aa
0.20 = aa
From this you can calculate the allele freq (p and q) of your initial population?
A's in AA = 2 x 0.55 = 1.1
A's in Aa = 1 x 0.25 = 0.25
Total A's = 1.1 + 0.25 = 1.35
A = 1.35/2 = 0.675 = p

a's in Aa = 1 x 0.25 = 0.25
a's in aa = 2 x 0.20 = 0.40
Total a's: 0.25 + 0.40 = 0.65
a = 0.65/2 = 0.325 = q

So, the EXPECTED HW Equil gen freq that correspond to the above allele freq are: (USE p^2 + 2pq + q^2 = 1)
0.675^2 = 0.46 = AA
2 x 0.675 x 0.325 = 0.44= Aa
0.325^2 = 0.1 = aa
Check: 0.46 + 0.44 + 0.1 = 1
Next Compare:
Observed to Expected using Chi Square Table, (w/degrees of freedom from allele freq, then n = # of choices = AA + Aa + aa = 3, so:
df = n-1 = 3-1 = 2
Now, check statistics from Chi Sq. table line #2, if less than a 0.5 difference then evolution has occurred, if not then no evolutionary changes have taken place
2) Now generate the next gen of diploid indiv, F1 gen. and follow the above calculations, check Observ to Expect on the Chi Sq. table, is it in Equil?
3) Restablish the pop, check Observ to Expect on CST, is it in equil?
What are allele freq?
To find allele freq (p and q) of your initial pop.

Take the Observed Initial (assigned) Gen. Freq:
0.55 = AA
0.25 = Aa
0.20 = aa
A = 2 x 0.55 + 1 x 0.25 =
1.35/2 = 0.675 = p
a = 1 x 0.25 + 2 x 0.20 =
0.65/2 = 0.325 = q
check: 0.675 + 0.325 = 1,yes
Def: Sampling w/replacement?
Returning the alleles to the pop being sampled thus to maintain the probability of selecting any allele remains equal to its freq.
What are the 2 parts to the HW rule if all 5 conditions are met?
1) allele freq will stay the same
2) the gen. freq will always reach equilibrium and remain constant only after one generation of random mating
Def: genetic fixation
the loss of all but one allel at a gene locus in a pop, which is a common result of genetic drift in a small natural pop.
Def: Bottleneck Effect
it is one type of genetic drift efect that occurs when a pop endergoes a drastic reduction in size as a result of chance disasters such s volcano eruption, floods and hurricanes.
* So, by chance alone the allele freq of the survivors may vary considerably from those of the original pop
Steps to testing the Genetic Drift by the Bottleneck Effect:
1) establish an Initial pop of 100 diploid indiv w/a freq of 0.5 for each allele
2) Sample five pairs of alleles w/replacement. We will use thsi small sample to represent "survivors" of a random environmental disaster. These freq determine the allele freq for the next gen.
3) Re-establish a pop size of 100 indiv, w/the allele freq of the survivors. So, if 3AA, 1Aa, 1aa survived, then the new freq is:
p = ((2x3AA) + 1Aa)/10 total alleles = 0.7
q = ((2x1aa) + 1Aa)/10 total alleles = 0.3
So, you need 140 A (= 0.7 x 200 total alleles in the pop) and 60 a (= 0.3 x 200 total alleles in the pop)
4) repeat steps 2 & 3 above, effectively subjecting your pop to repeated bottleneck episodes, until ONE allele becomes fixed in the pop, such as ALL AA, Aa or ALL aa
Steps to testing Gene Flow by Migration:
Migration of individuals into or out of a pop results in Gene Flow. Both the rate and direction of migration and the starting allele freq of the pop can influence the rate of genetic change. Procedures:
1) Establish 2 pop's of 100 indiv. each, be sure to CHOOSE VERY different starting allele freq for each pop. For example, chossing 1 pop to start at freq of 0.5 and 0.5, while the other starts as 0.9 and 0.1
2) Select ten dipoid indiv. from each pop and allow them to migrate to the other pop by exchagning the allele between both pop.
3) simulate random repoduction in these new pop by randomly selecting, w/replacement, 100 indiv from each pop, be sure to record the genotypes in an organized table.
4) calculate the new allele freq (p and q) in the two pop following migration and reproduction
5) adjust you bean pop to reflect the new allele freq, p and q
6) repeat procedures 2-5 on the pop for several gen's until enough change has occurred to allow you to successfully report your results
7) Summarize the resutls
Steps to testing Directional Natural Selection:
This means a change in the environment that directly causes Natural Selection to occur in the allele freq. w/in a pop. Example, the pepered moth industrial melanism (the cause of air pollution changing the color of the tree trunk, therefor promting a change in the recessive allele, dark color, becoming the more dominant when evoiding predation from a bird.
1) Establish an initial pop of 100 individuals w/0.9 (a) light and 0.1 dark (A)
2) re-establish a new pop w/50% of the peppered moth being eaten and 10% of the dark being eaten. (Since dark can be either AA or Aa, you must remove 10% w/in each
3) calculatenew allele freq for the remaining pop, simulate gamete production among the survivors by re-establishing pop of 100 ind.
4) repeat steps 2 and 3 above, applying 50% versus 10% predation pressures on the new pop for several gen until you have sufficient evidence to report.
5) summarize your results
What are the 3 simulations of evolutionary effects to test when studying the effects of several violations of the HW conditions.
1) Genetic Drift by the Bottleneck Effect
2) Gene Flow by Migration
3) Directional Natural Sel.
What is a PROTOZOA, any defing characteristics?
Protozoa is The Animal-Like Protists, containing Eukaryotic organisms that do not fit easily into the other eukaryotic kingdoms, such as the Animalia, Plantae or Funji. We will study FOUR GROUPS of Protozoa, which can be conveniently separated by their means of locomotion:
1) The Sarcodines, amoeboid moving
2) The Ciliates, cilia swimming members of the Phylum Ciliophora
3) The Flagellates, the flagella-swimming flagellates
4) The Aplicomplexa, non-motile, most parasitic group, the Phylum Apicomplexa
it is a protozoa that produces cytoplasmic extensions generally called PSUEDOPODIA, which al differ in size, shape, and extent of microtubular support. Some sarcodines use their psuedopodia in locomtion, while others use theirs for food capture.
How do amoebas feed?
Food is broken down by hydrolic enzymes brought to the prey item when a LYSOSOME fuses w/the food vacuale, thereby forming a DIGESTIVE VACUOLE.
Phylum Rhizopda
The Rhizopoda is a Sarcodine, Amoeba proteus, all of which are unicellular and locomote by means of their RELATIVELY THICK, "ROOT-LIKE" PSUEDOPODIA, ALSO USED FOR FOOD CAPTURING
B) Characteristics:
psuedopodia; endoplasm, ectoplasm (plasmagel: stiff jelly-like,which is the clear portion of the cytoplasm that is seen just below the plasma membrane and the plasmasol: fluid like, which forms the outer margin of the endoplasm and acts to "anchor" the psuedopodia as they extend); contractile vacuole: which have a spherical shape and clear appearance several may exist it is used to expell water from the cell; nucleus: sinlge nucleus will generally have smaller organelles streaming around it, further identifying it; Food Vacuole: it generally possesses one or more, sometimes difficult to identify, but they tend to be larger and darker than most of the other organelles in the cell.
Phylum Actinopoda
this is a Sarcodine, Protozoa. It possesses long, thin, fixed pseudopodia called AXOPODIA, that are supported internally by bundles of microtubules.
Many of the Actinopoda secrete protective SHELLS or TESTS, which possess small holes through which the pseudopodia extend, which is used for food capture (bacteria, orgaic debris, very small protists), but not locomotion. These orgaisms do NOT actively locomote, but instead freely float in their aqueous environments.
Subphylum Heliozoa: are freshwater, spherical, naked actinopods w/thin radiating pseudopodia that make them resemble the sun. Unfortunately, there are NO living representatives to study, BUT BE AWARE OF THIS SUBPHYLUM
Subphylum Radiolaria: are a large group of marine actinopods that secrete perforated tests of silica (glass), these tests are generally radially or spherically symmetric, and are very delicate and attractive. When they die, their shells sink to the bottom of the ocean, where they accumulate to great depths. Slide studied: Radiolarian Strew
Phylum Foraminifera
this is a Sarcodine, Protozoa. It is shelled, free-floating marine sarcodine that possesses pseudopodia called RETICULOPODIA, which is thin, ray-like that extends through the test, and then interconnected to form a "net" where food is captured thus meaning phagocytosed, and digested.
Foraminifera tests are made of CALCIUM CARBONATE and are easily recognized b/c they are CHAMBERED and often coiled.
The Foraminifera has a snail like appearance of many of the shells, they also sink to the bottom when dead
the MOST COMPLEX of all protozoa. THey tend to be larger than most other protozoa and they show a HIGH DEGREE OF SUBCELLULAR SPECIALIZATION, w/many fixed regions of the cell specialized for different functions.
ALL ciliated are MULTINUCLEATED, w/nuclei specialized into MACRONUCLEI, which are active nuclei that are responsible for directing the "day-to-day" activities of the cell, versus MICRONUCLEI which are dormant and used only for genetic exchange during sexual reproduction.
ALL ciliates possess at least one macronucleus and at least one micronucleus.
THe ciliates are a more homogeneous group than are the sarcodines, and are therefore placed w/in the single Phylum Ciliophora formerly called the Phylum Ciliata.
Types of Ciliates:
Phylum Ciliophora (Paramecium caudatum), Stentor, Spirostomum.
Phylumm Ciliophora
this is a type of Ciliate. Example shown: Paramecium caudatum- a large, common freshwater often used in lab studies.
To slow the organism down, place a drop of PROTOSLO on top of the study.
Characteristics: Pellicle, Contractile Vacuoles, Macronucleus versus Micro"", Oral groove, Cytosome, Cytopharynx, Food vacuoles (fused w/a LYSOSOME to form a DIGESTIVE VACUOLE), cytopyge.
Feeding and digestion in Paramecium
using brewers yeast dyed w/Congo Red dye, under microscopic observation you can see the red yeast cells being swept through the oral groove and cytostome into the cytopharynx, watching closely youcan see the food vacuoles being pinched off and drift away from the cytopharynx. At some point the food particles will suddenly turn blue, which is an indication of when a LYSOSOME has fused w/the food vacuole, delivering a highy acidic solution. So, as the yeast are digested and the acid dissipates, the contents of the food vacuole will change from blue to green, to yellow, to orange and finally back to red again.
a) what is a Stentor
b) 7 characteristics
a) stentor is a very large ciliate

b) Characteristics:
1) natural blue colors
2) it has a very flexible PELLICLE than that of Paramecium
3) as it recovers from handling it goes from a ROUND BALL to a TRUMPET like shape
4) Its body is covered w/LONGITUDINAL ROWS OF CILIA
5) its ORAL GROOVE is surrounded w/a whorl of beating MEMBRANELLES, which are specialixed fan-like structures of fused cilia used to sweep fod into the oral groove
6) Large CONTRACTILE VACUOLES should be apparent
7) The nuclei of living Stentor are a bit difficult to see, due to their transparent nature, but the highly lobed or beaded MACRONUCLEUS can sometimes be observed when the cell rotates
a) what is a Spirostomum
b) characteristics
a) Spirostomum is a Ciliate
b) Characteristics:
1) it is one of the LARGEST protzoa, ciliates, up to 3mm in length
2) The PELLICLE is VERY flexible and associated w/CONTRACTILE FIBERS called MYONEMES, which allow the organism to move in a worm-like motion
3) long beaded MACRONUCLEUS
a) what is a FLAGELLATES
b) members
c) characteristics
a) FLAGELLATES are PROTOZOA- an animal-like protist
b) I)Phylum Zoomastigophora, which are ALL HETEROTROPHIC FLAGELLATES
1) Trichonympha: multiflagellated protozoan, live ENDOSYMBIOTICALLY w/in the guts of termites. This type of sybiosis is known as MUTUALISM, so the termite gains a food supply and the triconymphta gains a moist environment. They contain numerous FOOD VACUOLES visible.
2) TRYPANOSOMA: PARASITIC endosmbionts live in the blood of all classes of vertebrate animals. They cause the serious AFRICAN SLEEPING SICKNESS in humans. These parasites are passed on through the bite of tsetse fly.
II) Phylum Euglenophyta: formally an algae,
1) EUGLENE: are fresh waterforms that possess 2 FLAGELLA extending from an invagination in the anterior end called the RESEVOIR. They move in a worm-like contraction and extension of the body called EUGLENOID MOVEMENT. They are PHOTOAUTOTOPHS but are also HETEROTROPHIC when light is not available. Move with their FLAGELLA being whipped around and pulling them along in an anterior direction. PELLICLE is stiff, but also flexible. STIGMA or eyespot, located near the base of the resevoir, which acts as a shade that can turn on/off to detect the direction of the light and swim toward it. CONTRACTILE VACUOLE, single. NUCLEUS located in the center. CHLOROPLAST are scattered everywhere, green in color. Some chlorplast have white granule stuck on them, called PARAMYLON BODIES, which serve as an energy store
2) PARANEMA: freeliving Euglenoid flagellate, lacks CHLOROPLAST, leads a HETEROTROPHIC life, digest food through a CYTOSTOME near the anterior RESERVOIR. In the anterior end, CONTRACTILE VACUOLES are present.
1) CHLAMYDOMONAS: is a UNICELLULAR member of the VOLVOCALES, they have a single large, CUP SHAPED CHLORPLAST(might appear u-shaped in side view).
2) GONIUM: a they appear to eb FLAT, PLATE-LIKE shapes, live in colonies of 4-32 cells, they have a STIGMA and 2 FLAGELLA, DEFINITELY NOT Chlamydomonas cells, also, the swimming efforts of the colonies give it greater mobility, theses cells are conected by a gelatinous MATRIX.
3) Pandorina: another colonial form that occurs in SOID BALLS OF CELLS embedded in a gel. matrix. Colonies of 16-32 cells.
4) EUDORINA: large colonies, 16, 32, 64, 128 cells, which these colonies you'll begin to see a DIVISION OF LABOR and SPECIALIZATION OF FUNCTION between cells that are seen in more highly developed multicellular organisms.
5) VOLVOX: colonies are VERY LARGE HOOLOW SPHERES that include a single layer of 500-60,000 biflagellated cells, resembling CHLAMYDOMONAS, generally viewed w/a DEPRESSION SLIDE. They have a greater degree of CELL SPECIALIZATION and DIVISION OF LABOR, which is most pronounce in SPECIALIZED REPRODUCTIVE CELLS that lie in only 1/2 the colony. THese cells grow much larger than other VEGETATIVE (NON-REPRODUCTIVE CELLS). During ASEXUAL repro. these reprod. cells divide mitotically, forming balloon shaped DAUGHTER COLONIES inside the surface of the parent colonies. SEXUAL reproduction occurs w/egg and sperm by specialized GAMETOCYTE CELLS.
III) APICOMPLEXA: ALL INTERCELLULAR PARASITES, complex life cycle, they have a production of SPORE STAGE, the most important one is the PLASMODIUM, which produces MALARIA
PLASMODIUM: the parasite is spread by MOSQUITOES, c) Characteristics: Phylum Zoomastigophora either ingest their food by phagocytosis or absorb organic molecules from the environment. Most are unicellular, many live in colonies.
Trypanosoma have a single NUCLEUS, long flagellum runs parallel w/the body and together w/a fold of the plasma membrane forms a thin UNDULATING MEMBRANE
3 terms identifying Volvocine
1) increased number of cells and colony size
2) increased division of labor between colony members
3) increased interdependence of colony cells upon each other
A) what parasite produces MALARIA?
b) What are the 2 most common type in humans?
c) how is it spread/
b) the P. vivax and P. falciparum, being the most common and virulent forms
c) it is tranmitted by a mosquitoes bite, it has a COMPLEX LIFE CYCLE, the SPOROZOITES of the plasmodim are carried into the host w/the mosquitos saliva, then through the blood stream into the human host to the liver, it lives in the liver cells, produce MEROZOITES, which then overproduce causing liver cells to burst, they then enter the bloodstream and transform into cells called TROPHOZOITES, identified by a SIGNT-RING STAGE", SOME TRANSFORM INTO MALE AND FEMALE GAMETOCYTES
One great difference between protozoa and animals
animals are TURE multicellular organisms, thus meaning they have cells that are far more efficient at performing particular tasks than would be more generalized cells. THese groups of cells that perform their task are called TISSUES. Different types of tissues are organised into ORGANS, which are them orgainized into ORGAN SYSTEMS that make up the entire ORGANISM.
the study of tissue structure and function.
4 types of animal tissues
1) epithelial tissues
2) connective tissues
3) muscle tissues
4) nervous tissues
Epithelial Tissues
1) they cover and line surfaces, and many form specialized glands
2) found in every internal and external body surface, outside of you skin, surface of organs, the lining of your blood vessels, etc...
3) Characterized by having very little extracellular material present, so the cells of these tissues are tightly packed together, they possess a BASEMENT MEMBRANE made of secreted proteins and glycoproteins that serve to anchor the tissue to underlying tissues
3 Types of epithelial tissues
They are id by, the NUMBER OF CELL LAYERS in the tissue, and the SHAPE OF THE CELLS in the tissue.
The number of layers refers to being either a single layer of cells called, SIMPLE EPITHELIAL TISSUES or made up of tow or more cell layers called, STRATIFIED EPITHELIAL TISSUES. PSEUDOSTRATIFIED EPITHELIAL TISSUES consist of a single layer of cell that appear to be stratified, but are not.

3 different shapes are recognized:
1) SQUAMOUS cells are thin and flat
2) CUBOIDAL cells are as wide as they are tall
3) COLUMNAR cells are taller than they are wide
Stratified Squamous epithelium
Slide examined, FROG SKIN, this tissue is limitted to the outer surface of the organ, or the EPIDERMIS. This tissue is continually renewed by mitotic divisions of the deepest cell layer.
Also, in this slide, id the BASEMENT MEMBRANE, visible as a somewhat clear layer between the epithelial epidermis and the connective tissues of the underlying dermis
Simple Cuboidal Epithelium
Slide, KIDNEY SECTION, lok for an area w/a high concentration of small rings- these are the KIDNEY TUBULES SEEN IN CROSS SECTION. At high power, you can see these cells circling a space called the LUMEN of the tubule, surounding the ring of cells is the BASEMENT MEMBRANE
Simple Columnar Epithelium
Slide, FROG SMALL INTESTINE X.S., the surface is folded into a finger-like shape called VILLI.
When the surface of the cells appear darker and perhaps even fuzzy, this is called THE BRUSHED BORDER, which consists of many microscopic folds in the plasma membrane of the cells called MICROVILLI. Interspersed between the normal columanr cells will be specialized cells called GOBLET CELLS, which secrete mucous to lubricate and protect the intestinal lining. THey are vase or goblet like-shape which is filled w/mucous.
Connective Tissue
Large group of tissues that function to connect, pack ans support organs and other tissues.
Characterized: by there widely spread out cells, which are widely separated by a large amount of extracellular material making up a MATRIX. Matrix materials are secreted by tissue cells and include one or more types of PROTEINACEOUS FIBERS and embedded in a GROUND SUBSTANCE, which is made up of dense liquid or gel. mixture of glycoproteins and polysaccharides. The most common types of fibers present are COLLAGENOUS FIBERS, which are very tough and resistant to stretch;made up of COLLAGEN PROTEINS and ELASTIC FIBERS, which are made of stretchable ELASTIN PROTEINS that allow the tissue to stretch and recoil in a rubbery fashion
6 types of Connective Tissue
1) Loose Connective Tissue: connects and softly packs other tissues together w/in organs, made up of loosely packed fibers, most of the darkly staining nuclei belong to cells called FIBROBLASTS, which secreted the components of the tissue matrix. MACROPHAGED are visible in far fewer numbers, distinguished by the presence of a grainy cytoplasm around the nucleus of the cell.
2) Dense Fibrous Connective Tissue: is densely packed w/material, dominated by COLLAGENOUS FIBERS packed into parallel bundles. Slide, TENDON SLIDE, nuclei of FIBROBLAST are seen squeezed between bundles
3) Adipose Tissue: tightly packed cells, ADIPOCYTES, which store large amounts of triglycercides w/in intracellular FAT VACUOLES. It lloks like chicken wire. Adipose tissues serves not only as a storage site of high energy triglycerides, but also as a cushioning material for delicate parts of the body. example, your kidneys are surrounded by a cushioning layer of adipose tissue
4) Cartilage: serves as a supportive/protective function. It is found when a strong, yet flexible, material is needed. It consists of cells called, CHONDOCYTES, which secrete a dense, gel. ground substance called CHONDRIN as well as COLLAGENOUS FIBERS. The chondrocytes occupy small cavities or spaces called LACUNAE. Cartilage has NO BLOOD VESSELS running through it, however waste disposes slowly and damages take time to heal.
Types of Cartilage: HYALINE CARTILAGE, is smooth, moderatly flexible material that if found protecting the ends of your linb bones and amking up the bridge of your nose, your voice box, and the supportive rings that keep your trachea (windpipe) open. Made up of COLLAGENOUS FIBERS, which are not packed into bundles and not to small to see. Elastic fibers are also present, more flexible.

FIBROCARTILAGE a much stronger and able to withstand greater pressure than hyaline cartilage, which has a higher density of collagenous fibers. Example: it is found w/in the disks that lie between the vertebrae of the spinal column.
5) Bone
6) Blood
a connective tissue, which is living and made up of a solid, crystaline matrix that has imbedded w/in the network of collagenous fibers. Used for support and protection.
The cells of bone are called OSTEOCYTES, which lay down the bony matrix in what is called a HAVERSIAN SYSTEM, where the matrix material is secreted in concentris layers called LAMELLAE that surround a canal called a HAVERSIAN CANAL. Haversian canals house blood vessels and nerves that supply the bone. Between the lamellae lay numerous lacunae that house the osteocytes. Together, one Havesian canal w/its surroundinglamellae and lacunae are called an OSTEON. Osteocytes pass materials by means of small canals called, canaliculi.
a connective tissue that has two types, red-blood cells "ERYTHROCYTES", which carry oxygen and white-blood cells, "LEUCOCYTES", which make-up the body's defense system against foreign organisms and particles.
The blood cells are widely spaced w/in a matrix called the PLASMA, which contains a liquid ground substance called SERUM and various proteinaceous fibers. Majority of the fiers belong to a group of proteins called ALBUMIN PROTEINS, which make blood viscous, additionally fibers form blood clots when necessary.
Slide viewed, HUMAN BLOOD SMEAR, you can see the cell NUCLEI, under high power you can see anucleated erythrocytes, which make up majority of the cells. Erythrocytes are packed w/molecules of oxygen-caryng hemoglobin, and resemble small disks that concave on both sides, often lighter in their centers and may even look like little donuts.
3 types of Muscle Tissue
1) skeletal muscle: contact to and moves the skeleton, it is the MOST common type of muscle in vertebrates, making up what we commonly refer to as meat. Its cells are VERY LONG, UNBRANCHED, CYLINDRICAL-SHAPED CELLS that are MULTINUCLEATED. It is a striated muscle, possessing many small transverse striations caused by the internal organization of the contractile proteins. Contractions are usually VOLUNTARILY controlled.
2) Cardiac Muscle: is found ONLY in the heart of animals, contracting to create pressure to drive blood through the body. These contractions are usually INVOLUNTARY. Cardiac muscle is striated due to its organization of contractile proteins, but they are often difficult to see in preserved slides. The cells are SHORT, STOCKY CELLS THAT ARE SOMETIMES BRANCHED, but always UNINUCLEATED and easily id by the presence of INTERCALATED DISKS, which look like especially dark and thick striations, but are actually specialized junctions connecting the ends of adjacent cells.
3) SMOOTH MUSCLE: normally under INVOLUNTARY control, it is found in your digestive organs and in blood vessels, they appear smooth, they are NONSTRIATED. Individual cells of smooth muscle are THIN, UNBRANCHED AND SPINDLE SHAPED (tapering towards theor ends). The cells are also UNINUCLEATED. Often confused w/the fiber bundles of dense fibrous connective tissue.
Nervous tissue
is specialized for communication by cells called NEURONS. Neurons include the largest cells of you body, with the longest extending from your lower back to the muscles of you feet. Neurons are metabolically very active cells that produce nervous impulses and transmit them rapidly to other neurons, muscle cells and or gland cells of your body.
In addition to neurons, nervous tissue includes numerous other types of cells that are collectivley referred to as GLIAL CELLS. These GLIAL CELLS provide various types of metabolic and other support to the highly specialized neurons.

Slide, SPINAL CORD SMEAR, present are large stellar (star shaped) CELL BODIES of motor neurons. Also, a single NUCLEUS AND NUCLEOLUS is usually visible, as are small, darkly staining NEUROFIBRILS w/in the cell body. Extending from the cell bodies are single, long AXONS, which serve to transmit nervous impulses to other cells over sometimes very long distances and numerous DENDRITES, which recieve info from other neurons. SCHWANN CELLS are also present, which they tend to wrap themselves around axons and help neurons to increase the spreed of the nervous impulses. MODEL PRESENTED SHOWING THE RELATIONSHIP BETWEEN NEURONS AND SCHWANN CELLS
a) what is Phylum Porifera
b) what are 4 identifying characteristics?
a) The Sponges
b) characteristics OF HOW THEY FIT THE DEFINITION OF ANIMALS in that:
3) their cells LACK CELL WALLS
** Their body orgaization, is very simple as compared to all other animals, but most of their cells do not function togetheras do true tissues. Sponges are generally considered to LACK TISSUES altogether or to possess a few tissues at best and have no organs or organ system.
These differences have led zoologists to place the Porifera into a separate branch, the PARAZOA, whose ancestors are believed to have branched off the main animal lineage very early in naimal evolution.
Sponges are SESSILE organisms that attach themselves to their substrates and obtain their nutrients by FILTER-FEEDING. Most are marine, but freshwater forms do occur. Some are radially symmetric, but many show NO symmetry at all.
General body structure and function of Sponges
Porifera-"pore-bearing" have bodies that are built around a series of interconnected pores and canals through which water is constantly pumped. The porous body is supported by SPICULES and/or FIBERS made of SPONGIN, a protein that is similar to collegen but is found only among sponges. Spicules and fibers are secreted by cells called SCLEROCYTES and SPONGOCYTES, all of which is imbedded w/in a gel. matrix called the MESOHYL. The outer surface of sponges are covered by flat, squamous-like cells called PINACOCYTES. In some sponges, cells called POROCYTES are interspersed between pinacocytes to form small pores through the body surface. Porocytes are capable of contracting to alter the diameter of the pores, the rate at which water passes through. The pores eventually open to canals or cavities whose walls are lined w/flagellated cells called CHOANOCYTES. CHOANOCYTES serve as the PRIMARY FEEDING CELLS OF SPONGES, by which they beat their flagella, they create small currents that draw water through the sponges body. These cells are also known as "collar cells", b/c theuir flagella are surrounded by a thin collar made up of mesh-like network of thin, interlocking cytoplasmic extensions that are supported internally by microtubules, which the collar serves as a net or filter, trapping bacteria and bits of organic material to be phagocytosed into food vacuoles. By SIMPLE DIFFUSION water passes in bringing oxygen and out removing waste, so no circulatory, respirtory or excretory systems are needed in these animals. Nutrients are passed through the sponges body by cells called, AMOEBOCYTES (also called ARCHAEOCYTES). Amoebocytes crawl around the mesohyl of the sponge by amoeboid movement. When a choanocyte captures food particles, some is digested and the reast is passed onto amoebocytes, which they eat some and feed then feed other non-food-capturing pinacocytes, sclerocytes and so on. These cells overall possess specialization and differentiation of cells to the point where they are interdependent upon each other for survival, which is the TRUE hallmark of multicellularity.
3 types of Sponge Body Plan
* they each differ in their arrangement of water canals and location of choanocytes.
1) the simplest body plan, ASCONOID type, have small radially symmetric bodies that resemble either cylinders closed on one end or thin vases encompassing a central cavity called the SPONGOCOEL. the spongocoel itself is lined w/choanocytes. Water enters these simple sponges through pores called ESTIA (ostium, singular). These pores are lined by porocytes, and extend through the thin body wall to the spongocoel. From the numerous pores, water travels through the spongocoel and out a single exit pore called the OSCULUM.
2) somewhat more complex is the SYCONOID body plan: appear to be a stretched asconoid, followed by poking many thn finger-like invaginations and evaginations in the body wall to produced a highly convoluted body wall. Their bodies are radially symmetric and vase-like in shape, but their body walls appear to be folded in accordion-like fashion when viewed in longitudinal section. The evagination in this body plan are called RADIAL CANALS (b/c they radiate from the spongocoel), while the invaginations between them are called INCURRENT CANALS, which open to the surrounding environment through openings called OSTIA, while the radial canals open into the spongocoel through opening called APOPULES. Water is drawn into the OSTIA, through the incurrent canals, and then through microscopic pores called PROSOPYLES, which lead into the radial canals. CHOANOCYTES LINE THE RADIAL CANALS, and push the water through the apopyles, into the spongocoel, and eventually out a single OSCULUM.
3) The MOST complex water canal systems are found in LEUCONOID body plans. They lack central spongocoels and have asymmetric bodies. along the outer surfaces of these sponges lie MANY OSTIA and MANY OSCULA. Each ostium is associated w/an INCURRENT CANAL that may merge together as well as branch as they course into the sponge body on their way to CHAMBERS THAT ARE LINED W/CHOANOCYTES. Water is drawn into these chamber by the flagellar beating of the choanocytes, and then out through EXCURRENT CANALS, which also merge and branch as they run out of the sponge body to one or more oscula. Most sponges in the world are this type.
Sponge classifications
1) CLASS CALCAREA includes sponges that produce CALCAREOUS (CaCO,3) SPICULES, generally w/ONE, THREE, OR FOUR RAYS. All members in this class are ALL MARINE, and may have ASCONOID, SYCONOID, OR LEUCONOID BODY TYPES.
2) CLASS HEXACTNELLIDA, commonly called "glass sponges" b/c their skeletons consist of SPICULES MADE OF SILICA. The spicules are branched into usually SIX (HENCE THE NAME, "HEXA"), BUT SOMETIMES FIVE, RAYE. The spicules interlock into delicate skeletons that look like fine woven glass sculptures, which they are ALL LIMITED TO ASCENOID OR SYCONOID BODY TYPES.
3) The LARGEST CLASS of sponges, CLASS DEMOSPONGIAE, which includes about 95% of all sponge species. They are characterized by the production of SPONGIN FIBERS, which make up most of the skeleton. SILICA SPICULES ARE ALSO FOUND IN SOME SPECIES, possessing ONE TO FOUR RAYS and making up a minor portion of the skeleton. This class is MOSTLY MARINE, BUT SOME FORMS ARE FRESHWATER. All members in this class are LEUCONOID BODY TYPES.
is NOT a leuconoid sponge, its a representative asconoid sponge of the Class Calcarea. These small and simple organisms form colonies, vase-like in shape, possess a single visible osculum, and numerous ostia that are too small to be seen w/the naked eye. The members of the colonies are genetic clones having been produced by the asexual budding of one indiv. These buds grow out of the sides of larger indiv. These indiv. ALL share a common spongocoel, so it can be argued that they are actually just one organism. These forms of sponges however live quite well on their own.
Sycon = Scypha = Grantia
Sycon is another member of the Class Calcerea, has a syconoid body type. It has a single osculum, folding body style, numerous radial and incurrent canals that open to the outside by ostia, central spongocoel, apopyle, numerous darkly stained nuclei along the inside of the radial canals, which they belong to the CHOANOCYTES, and small PROSOPYLES are found in the walls between the incurrent and radial canals, and the internal MESOHYL region of the body walls, which is sometimes stained a faint pink or purple, but not always. Within the Mesohyl you should be able to find AMOEBOCYTES, along w/nuclei of additional types of cells.
Numerous small cluster of cells are scattered throughout the radial canals of the sponge, which are called AMPHIBLASTULA LARVAE- which are product of sexual reporduction. Like most sponges, Sycon is MONOECIOUS (hermaphroditic), an ability to produce both eggs & sperm. Gametes are produced by amoebocytes and only the sperm are released, which is then digested and transported to the eggs w/in the mesohyl, where fertilization occurs. CLEAVAGE occurs w/in mesohyl, the amphiblastula larvae break out into the radial canals, the ciliated larvae will then be carried out of the sponge by way of the osculum, swim about, anchor themselves to the substrate and develop into an adult sponge. Other types of larvae occur in some other sponges.
this is a sponge, Class Hexactinellida or Glass sponge, commonly called "Venus' flower basket", which has a syconoid body plan.
Class Demospongiae
is the largest class of sponges, however it is VERY difficult to examine microscopically. They similarly look like bath sponges. They have asymmetric body w/numerous OSTIA and OSCULA on its surface. The structure is made up of SPONGIN fibers. Some have only spongin skeletons, but others produce siliceous spicules. Both types were commonly used as natural bath sponges after they were repeatedly smashed and rinsed, removing both cells and siliceous spicules, then dried and shipped to market.
what are the Radiata?
it includes two phyla of RADIALLY AND BIRADIALLY SYMMETRIC animals that were formerly called the COELENTERATES- the PHYLUM CTENOPHORA. Members of both phyla consist of numerous types of cells, many of which work together as TRUE TISSUES. The cells are derivedfrom two embryonic germ of tissue layers called the ENDODERM and ECTODERM. Members or the Radiata are therefore said to be DIPLOBLASTIC.
The Cnidaria is from the Radiata group, it includes animals such as JELLYFISH, CORALS, and SEA ANEMONES. members of the Phylum Cnidaria are characterized by the possessio n of specialized cells called CNIDOCYTES, for which the phylum is named. Cnidocytes are specialzed epithelial cells that include capsule-shaped stinging structures called NEMATOCYSTS, each functioning as microscopic weapons used in prey capture and protection. Adult cnidarians include thin body walls organized around an extensive cavity called the GASTROVASCULAR CAVITY (also called COELOENTERON), which serves primarily as the gut of digestive cavity of the animal. Food enters the cavity by way of MOUTH, and waste products leave the mouth, this cavity is BLIND-ENDED, meaning closed on one end. These animals have NO ANUS. Lining the Gas. Cavity, IS A LAYER derived from the embryonic endoderm is called the GASTRODERMIS.
Covering the outside of the body is a leyer derived from the embryonic ectoderm called the EPIDERMIS. Between the two body layers is a space filled w/a gel. matrix called the MESOGLEA.
* In simplercnidarians, the mesoglea is thin, primarily gel. and analogous to the meohyl of sponges.
** In more complex cnidarians, the mesoglea may include various fibers and amoeboid cells.

B/c the body walls are thin the cnidarians have a very high surface area relative to the volume of their tissues. Individual cells are always very close to the water surrounding the animal. They have no need fro specialized circulatory, gas exchange, or metabolic waste removal (excretory) systems. Extensive gas. cavities allow water to contact additional internal surfaces for even greater exchange. The GC palys a role in the support of the thin body walls. When the mouth is closed it serves as a HYDROSTATIC SKELETON, providing an internal and compressible volume of water that the body walls can contract against which in the end helps the body maintain its shape.

Two basic body form are among the Cnidaria, a SESSILE POLYP form and a motile, free-swimming MEDUSA form. Many species exhibit both body plans occurring in different stages in their life cycles. In such cases, an ALTERNATION OF GENERATIONS is seen between usually asexual polyp and sexual medua stages or "generations".

The Cnidaria are divided into three classes:
2) CLASS SCYPHOZOA: includes TRU JELLFISH, whose life cycles are usually dominated by medusae
3) CLASS ANTHOZOA: includes SEA ANEMONES and CORALS whole life cycles include ONLY POLYPS
Class Hydrozoa
members of the hydrozoa have well defined epidermis versus gastrodemis layers, and a thin, gel. mesoglea. Both marine and fresshwater formas occur, most show a clear alternation of polyp versus medusa gen. some hydrozoans are solitary, but most are colonial.
2 freshwater types studied:
1) Hydra
2) Obelia

Marine type studied:
1) Physalia
is a common freshwater Hydrozoan, most commonly studied in zoo courses.
It is important to understand that it differs from most hydrozoan polyp in 3 ways:
1) Medusa stages are absent in Hydra; the polyp form is capable of both asexual reproduction by BUDDING and SEXUAL REPROD. involving the production of haploid gametes by reproductive organs, or gonads.
2) Some species of Hydra are MONOECIOUS, while most are DIOECIOUS ( HAVE SEPARATE MALE AND FEMALE SEXES). Almost all other hydrozoans and cnidarians as a whole are strictly DIOECIOUS.
3) Hydra is capable of locomotion, wheras most hydrozoan polyps permanently fix themselves to the substrate. When locomoting, hydra releases itself from the substrate and slowly tumbles of 'flips" end over end.

General body Structures: BASAL DISC; TENTACLES, which are used to capture food and transport it to the central MOUTH; the HYPOSTOME, WHICH IS THE DOME-SHAPED REGION LOCATED BELOW THE MOUTH and between the tentacles; and one or more BUDS may be present is a miniature version of the parent. The bud and parent share a common Gas. Cavity till the bud pinches off and fends for itself. Cnidocytes and nematocysts are present, the bumps are CNIDOCYTES and lying inside is the NEMATOCYSTS. sTICKING OU THE CNIDOCYTES is a small hair-like structure, these are called CNIDOCILS.
3 types of Nematocysts
1) PENETRANT NEMATOCYSTS: pierce the bodies of prey items:
2) VOLVENT NEMATOCYSTS: entangle or snare
3) GLUTINANT NEMATOCYSTS: trap prey by sticking to them
2 types of polys present in the Hydra
1) Hydranth or called GASTROZOOID- feeding polyp
2) GONANGIA or GONOZOOIDS - reproductive polyps, produce small MEDUSA through the process of BUDDING, they can be seen sticking to the sides of the central BLASTOSTYLES of the gonangia (w/in the perisarc)
Obelia Medusa
this a free-swimming Hydra, Obelia. It normally swims w/its EXUMBRELLAR SURFACE up and the concave surface, the SUBUMBRELLAR SURFACE down.

Also, present are TENTACLES that extend off the rim of the organism, along w/present bumps that are cnidocytes w/in them are the nematocysts, along w/a cnidocil sticking out.

In the center is the MOUTH, that is attached to the end of the MANUBRIUM. Food travels through the mouth and the manubrium into a BRANCHED GASTROVASULAR CAVITY that branches into FOUR RADIAL CANALS that are continuous w/a CIRCUALR CANAL (also called a RING CANAL) that runs around the margin of the umbrella. Each of the HOLLOW TENTACLES is continuous w/the circular canal. Water moves in/out of the gas. cavity, it carries not only food, but also oxygen and metabolic (excretory) wastes.
Also visible, a thin flap of tissue called VELUM, which serves to narrow the opening of the umbrella shaped body as it contracts while swimming, which allows the animal a more forceful expel of water as it swims, propelling itmore effectively. VELUM'S are ONLY found in medusa of the CLASS HYDROZOA.
Sexual reproduction step in the Obelia, Medusa stage.
they are Dioecious, the GONADS of hydrozoan medusa DEVELOP FROM THE ECTODERM, located along the outer subumbrellar surface just below the radial canals.

3rd PLANULA LARVA are produced: which swims aroung and anchors itself to the substrate and develops into a polyp colony, therby completing the life cycle.
SIPHONOPHORES are predatory, oceanic, colonial hydrazoans that are common in troficaland subtropical waters. They can live in colonies that include 1000's of individuals. This is a potentially dangerous form know as the Portuguese man-o'-war.
Present is a gas-filled float, known as a PNEUMATOPHORE, are thought to be a single modified polyp used to catch the wind to move this freely-floating colony along. Hanging below the pneumatophore is long TENTACLES that can reach several meters in lenght, theses tentacles are different types of modified polyps and medusae. Some are specialized for stinging, others feeding, others for reproduction. Instead of separate polyp and medusa stages, the colony is POLYMORPHIC in that both stages are present, polyp and medusa stages.

Food consists mostly of fish, some quite large, the toxin delivered by the Physalia can be very painful and potentially deadly to humans that are sensitive to it.
Class Scyphozoa
from the Radiata, Phylum Cnidaria, includes the TURE JELLY-FISH, all marine. The MEDUSA IS THE DOMINANT STAGE in the life cycle, w/the polyp gen. reduced and inconspicuous.
Characteristics: they possess a THICKER MESOGLEA than do the Hydrozoa, and the layer usually CONTAINS PROTEINACEOUD FIBERS AND AMOEBOID CELLS. Medusa LACK A VELUM, Hydrozoa don't.
They are generally much larger in size. The largest scyphozoan, Cyanea, reaches a diameter of 2 meters, w/tentacles up to 70 meters in length.

Slide Viewed: Aurilia, the common Moon-jelly

Body structure present:
Four long ORAL LOBES or ORAL ARMS extending from the center of the umbrellar body, which are an extension of the Manubrium and serve to capture and deliver food to mouth. The mouth leads into a very short STOMACH, which opens up to FOUR GASTRIC POUCHES, which each carry a GONAD. In each gastric pouch there are numerous short tentacles-like GASTRIC FILAMENTS, which are armed w/cnidocytes and are used to hold larger prey items w/in the gas. cavity. From the gastric pouches the gas. cavity branches into numerous RADIAL CANALS that extend outward and are continuous w/the CIRCULAR CANAL of the outer margin of the body.

Food is partially digested by enzymes secreted by gastrodermal cells and the gastric filaments. The partially digested food particles are then distributed throughout the body via the highly branched gas. cavity.

The outer margin of the medusa is lined w/tentacles and is scalloped into eight(or some other multiple of four in other species) regions. Located w/in each of the eight marginal indentations of the Aurelia is sensory structure called a RHOPALIUM. Each includes a STATOCYST or equilibrium organ and an OCELLUS or simple photoreceptor. These sensory receptors send info into the animals NERVE NET, allowing the animal to adjust its body position and to detect and respond to the presence and direction of light.

Reproduction: the GONADS are DERIVED FROM EMBRYONIC ENDODERM, as opposed to the ectoderm gonads of the Hydrozoa.

Members of the Scyphozoa are DIOECIOUS.

Gametes are shed out of the mouth and eggs are retained by females w/in grooves of the oral lobes, fertilization occurs and embryos develop w/in these same lobe grooves.
Finally, ciliated PLANULA LARVA are released, anchoring themselves to a substrate and metamorph into a FEEDING POLYP phase known as a SCYPHISTOMA, this polyp tends to have more tentacles than the hydra. The scyphistoma feed fro awhile and then transforms into a REPORDUCTIVE POLYP called a STROBILA, developing medusa stack one ontop of another in this stage. As the strobila pulses the medusa (asexual buds) rythmically pop off, producing young medusae, called EPHRAE (ephrya, singular), they are not quite umbrella shaped. The ephyra body consists or eight lobes, each w/a rhopalium situated near its end. As the ephyrae grow they will fill into form the umbrella shape of adult medusa.
all members of the Class Anthozoa are typically SESSILE MARINE FORMS that attach to rocks, shells and other hard surfaces. This largest class of the phylum Cnidaria includes the ANEMONES AND CORALS.
Characteristics: they LACK A MEDUSA in their life cycles, they have a presence of AMOEBOID CELLS IN THE MESOGLEA, and ENDODERMALLY DERIVED GONADS.

** The anthozoans represent the MOST highly specialized polyps of the Cnidaria.
a) Sea Anemones
b) Characteristics
c) Feeding
d) reproduction
a) are from the Class Anthozoa, Phylum Cnidaria, RADIATA.
B) characteristics: are large, soiltary marine polyps that look like fleshy flowers.
They possess specialized tentacles that give the body a BIRADIAL SYMMETRY.
They have a SLIT-SHAPED MOUTH surrounded by numerous tentacles ona flattened ORAL DISC. This opening lead to a tube-like PHARYNX that hangs down into the GASTRO. CAVITY, W/in the body is a folded gastrodermis, pleat-like SEPTA or MESENTERIES. Some connect to the pharynx, which makes the body look like a spoked wheel. Gas.Cavity runs through each of the tentacles, the body walls are thin w/a large surface area.

c) Feeding: prey, such as fish are captured and pushed down into the pharynx. contractions of the pharynx serve to push the food down into the gav. cavity in a swallowing0like manner. Regions of the septa are loaded w/cnidocytes and enzymes secreting cells. Prey are therefore partially digested extracellularly, followed by phagocytosis and final intracellular digestion in typical fashion.

Reproduction: occurs ASEXUALLY by splitting of the body called LONGITUNIAL FISSION, REGENERATION of the body fragments, and through gamete production by gonads that develop on the walls of the septa. Gametes are released from the gas. cavity through the mouth asn fertilization is external. Zygots develop into PLANULA LARVAE, which settle down and metamorphose directly into young anemones
a) Corals
b) Characteristics
c) Feeding
d) Reproduction
a) Coral is from the Class Anthozoa, Phylum Cnidaria, Radiata. Most of the Anthozoans are one or another type of coral.
b) charasteristics: they have a HARD OR STONY APPERANCE, which is the most common and familiar type of corals. Stony corals normally LIVE IN LARGE COLONIES of very small polyps. The polyps are similar to the structure to those of sea anemones. Members of the colony are interconnected by thin sheet-like extensions of the body wall. Underneath both the polyps and this interconnected tissue sheet is a calsium carbonate skeleton that has been secreted by the epidermis. the skeleton is secreted around the bases of the polyps, forming small cup or grooves into which the polyps can retract. The precise shape of the skeleton depends on the arrangement and distance between individual polyps.
Soft coral polyps live on top of their skeletons and makes them very delicate.

*Corals are easily killed by careless divers and swimmers that stand on them.

** Hard corals are highly important ecologically b/c they build reefs that provide homes for countless fish and invertebrates.

A GOOD example is the GREAT BARRIER REEF OF AUSTRALIA, these are coral reefs that HOUSE SYMBIOTIC DINOFLAGELLATE ALGAE called ZOOXANTHELLAE w/in their bodies that are located w/in gastrodermal cells, that are held w/in vacuoles, but are not digested. Up to fifty algal cells can be housed in a single gastrodermal cell.
this is a result of zooanthellae being expelled from corals, it is thought that this is stimulated by stresses associated w/unusually warm temperatures, and may be another consequence of global warming.
Sea Fan
is another type of coral from the Class Anthozoa, Phylum Cnidaria, Radiata.
Sea Fans are colonial corals whose SKELETONS ARE VERTICALLY FLATTENED. Colonies can reach heights of over two meters, yet require very little substrate on which to anchor themselves, which is an advantage in coral reef communities where space is limited. The sea fan colonies are impregnated w/calcium carbonate, they are much more flexible than skeletons of stony corals and bend w/prevailing water currents and waves. Sea fans owe their flexibility to proteinaceous fibers that make up the bulk of their skeletons. They are NOT reef builders, but are common among reef communities.
Phylum Ctenophora
Members of this Phylum were once considered to be closely related to cnidarians b/c they are DIPLOBLASTIC, possess GELATINOUS MATRIX layers, and their bodies superficially resemble medusae. The ctenophores are very different than cnidarians in 4 ways:
1) ctenophores possess NO CNIDOCYTES
2) their symmetry is ALWAYS biradial, w/many possessing paired tentacles and other flattened in a dorso-ventral manner.
3) LOCOMOTE BY CILIA, which are organized into small rows called COMBS
4) they differ in their possession of FLOW THROUGH DIGESTIVE TRACTS, w/both a MOUTH ANS AN ANUS.

Only 100 species of these PELIGIC and OFTEN DEEP WATER organisms have been identified. It is known that many trap small prey items itno the mouth. Ctenophores tend to be small, less than half a centimeter to several inches in length, some flattened ribbon-like forms are known that extend to about a meter in length. Many are bioluminescent.

Body parts to know:
1) rows of combs
2) highly branched digestive tract
3) mouth on one end
4) anus or series of anal pores on the other end
5) cilia
6) gelatineous mesoglea
Acoelomate flatworms
these animals are the most primative members of the BILATERIA. They are more complex than any Radiata, they show moderately developed cephalization, w/several types of specaialized sensory organs located in a recognizable anterior HEAD or CEPHALIC REGION of the body.


Their body arrangement serves the acoelomates well, as they actively locomote, primarily in a forward direction, in search of food, mates, etc...
As their name inplies, THEY LACK INTERNAL CAVITIES - between the gut and outerbody walls, their bodies are instead packed w/mesodermally-derived cells. In many other ways they are similar to protostomes:
1) their embryos go through SPIRAL, DETERMINATE CLEAVAGE

They arose early in the evolution of the Bilateria, and probably shared an ancestral lineage w/the protostomes
Phylum Platlhelminthes
are The Flatworms
they may be marine, freshwater, and even terrestrial. Most are free-living forms, but many are parasitic on other animals. They are relatively simple animals, possessing blind-ended GASTROVASCULAR CAVITIES that function similarly to those of the Cnidaria. They are more complex than the cnidaria b/c they possess numerous organs and are said to show an ORGAN LEVEL OF ORGANIZATION. The interior is packed w/loosely packed mesodermal tissue called PARENCHYMA tissue. Their is NO circulatory, respiratory system, but extracellular body fluids do perlocate between cells (and are called INTERSTIAL FLUIDS) to help distribute nutrients, gases and waste products.

Well developed organ systems are seen providing the digestive, repoductive, nervous and muscular needs of the body.
3 major classes and 1 minor one of Phylum Platyhelminthes
these 3 classes are divided by their differing degrees of parasitism.
1) CLASS TURBELLARIA-includes all of the free-living FLATWORMS
2) CLASS TREMATODA - includes animal parasites called FLUKES
3) CLASS CESTODA - includes internal digestive system parasites of animals called TAPEWORMS
4) CLASS MONOGENEA- also includes FLUKES, but these differ from the Trematoda in being primarily ECTOPARASITES (external parasites), which have simpler life cycles involvong only one host. This is a very small class that will NOT be studied.
Class Turbellaria
genus Dugesia- from the Phylum Platyhelminthes- the flatworms.
Most free-living flatworms are marine, but freshwater and even terrestrial do occur. Free-living freshwater forms commonly known asa PLANARIANS are easily obtained from streams, ponds, etc.
Form of locomotion: they use THE CILIA that covers the VENTRAL (lower) surface of the body, in addition their body secretes a thin sheet of mucous over which the body can more easily glide. Their body has the ability to contract in various ways, they possess TRUE MUSCLE, and different bands run in a longitudinal, circular, diagonal and dorsoventral directions of the body. allowing full contortion.

Characteristics: 2 eyes that appear to be crossed due to the presence of pigmented shades situated on the medial side (medial = closer to the midline) of each eye. Most planarians are negatively phototrophic, moving away from the light when possible.
On the sides of the head are projections called AURICLES, that are well supplied w/chemical and touch receptors. Inside the head is a primitive "brain" consisting of two neural GANGLIA, or clusters of neuron cell bodies. These cell bodies recieve sensory imput from the various receptors, process the information and send out commands to various parts of the body via NERVE CORDS that run the length of the body. Their BRAINS show a limited ability to learn.

FEEDING: the planarian smells food w/its auricles, extend out its muscular PHARYNX out of its vetnral surface and uses it to probe there meals, then they proceed to sit on it, while they eat blocking the ability to view their pharynx. Cells along the rim of the pharynx secrete digestive enztmes that loosen small pieces of food. Muscular contractions draw the food into the pharynx and itno the gas. cavity. Digestion is similar to a cnidarians, enzymes help break down the larger food pieces and the gas/cavity distributes the food throughout the cavity.

Viewed body structure:
1) gastrovascular cavity
2) single anterior forward trunk
3) 2 posterior (rear) trunks
4) lateral branches of the gas. cavity are DIVERTICULA.
this is a FLUKE, fromthe Phylum Platyhelminthes, flatworms.

Slide viewed:
Clonorchis sinesis: commonly called FLUKES, they are endoparasites of animals, and their bodies show adaptations for this specialized mode of life.

1) they possess 2 suckers on their ventral surfaces for which they attach themselves inside their hosts
2) their outer surfaces are covered w/a specialized epithelium called the TEGUMENT, which is nonciliated, syncytial layer that protects the flukes fro their hosts digestive enzymes and immune systems.
3) anterior MOUTH surrounded by ORAL SUCKERS
4) 1/4 of the way down the body is a 2nd VENTRAL SUCKERS, also called ACETABULUM, which are used to attach to the walls of the liver.
5) food is sucked intothe mouth by means of a muscular PHARYNX, visible just posterior to the mouth
6) Food travels through a short esophagus and into 2 branches of gas. cavity called the DIGESTIVE or INTESTINAL CAECAE
7) EXCRETORY PORES located at the posterior end, this is where the nitrogenous wastes are dumped out of the body
8) EXCRETORY BLADDED: serves as as collecting site for waste fluids collected by flame cells
10) flukes are MONOECIOUS like all flatworms
11) testes: sperm is produced here and passed to the MALE GENITAL PORE by the thin DUCTUS DEFERENS
12) WHEN MATING SPERM are recieved by the SEMINAL RECEPTACLES of the female reproductive tractm usually stained pink that is anterior to the testes, these receptacles are capable of storing sperm for considerable lengths of time and the eggs can be continually fertilized long after mating has occured
13) eggs are produced by the OVARY, which is smaller and anterior to the seminal receptacle,
14) the eggs pass toward the large UTERUS, they are then fertilized by hte sperm from the small seminal recepticle
15) then filled w/nutrients from the YOLK GLANDS, which are visible as many small grainy structures along the sides of the animal, lateral to the digestive caecae.
16) the fertilized eggs, develop miracidia w/in them as they pass through the long convolutes uterus toward the FEMALE GENITAL PORE
Chlonorchis has a complex life cycle: adult flukes produce eggs in their human definitive hosts, which leaves the feces, into water, ate by snails that serve as the intermediate host. These eggs hatch w/in the snail into a larval form called a MIRACIDIUM, which they reproduce ASEXUALLY w/in the snail, producing several other stages, all of which feed on the snails tissue (so, one miracidium can give rise to 1000's of larval forms), eventually the larval give rise to CERCARIA, which swim free seek out specific fish that serve as the second intermediate host. They enter the fish tby burrowing directly through the skin, where they lay down a heavy encysting coat an lie dormant as METACERCARIA, which are the form that infect humans if the infected fish is ingested, the metacercaria are then freed and make their way to the human beings liver.
includes the TAPEWORMS, fromthe Phylum Platyhelminthes- the Flatworms

slide viewed: Taenia pisiformes

these are the highly specialized, ribbon-shaped endoparasites that live in the intestine of vertebrate animals, including humans.

the life cycles of tapeworms are not as complex as the trematodes, commonly found in cats & dogs, the intermediate hosts are rabbits, adult tapeworms produce 1000's of eggs, which are carried out of the body w/the feces. The eggs may be digested by rabbits that eat contaminated grasses. The eggs hatch w/in the rabbits and develop into larval form called, ONCOSPHERES, which encyst in the liver till a dog or cat eats the rabbits liver, which they become the definitive host.

1) SCOLEX, located on the anterior end is equiped w/numerous SUCKERS and a ROSTELLUM ringed with HOOKS w/which the tapeworm latches onto the inner walls of the hosts intestine.
2) tapeworms are ABSENT BOTH SENSORY ORGANS AND A MOUTH, TAPEWORMS LACK DIGESTIVE ORGANS ALTOGETHER, they digest nutrients directly across their body walls.
3) the syncytial TEGUMENT of tapeworms is specialized for such absorption, being covered w/small microscopic folds to gratly increase the absorptive surface area, as well as to protect the tapeworm from the digestive enzymes of its host.
4) the tapeworms body consists of repeated segments called PROGLOTTIDS, which are continually PRODUCED BY THE SCOLEX BY ASEXUAL BUDDING.
5) EXCRETORY CANALS run longitudinally through the segments, these canals are coninuous between segments, collect nitrogenous wastes and excess water from flame cells, as in other platyhilminthes
6) Repoductive organs: these tapeworms are monoecious, the TESTIS are scattered thoughout the proglottids, they produce sperm, which are carried by tiny ducts called VASA EFFERENTIA from the testes to the VAS DEFERENS or DUCTUS DEFERENS, here the vas deferens carry sperm out of the body through the copulatory organ the CIRRUS, which can be extended through the GENETAL PORE and inserted into the genital pore of another tapeworm fro cross fertilization.

** These same tapeworms can self fertiliz, w/copulation occurring between proglottids, if no other tapeworms are present w/in the host.

Sperm are then deposited in the VAGINA and are passed to the small round SEMINAL RECEPTACLE, near them lie two tufted OVARIES and to the posterior located YOLK GLAND, which the egg is produced in the ovaries travel toward the UTERUS through thin OVIDUCTS and are fertilized w/sperm in the seminal receptacles and supplied w/nutrients through from the yolk glands along the way.
7) further posterior are even larger GRAVID PROGLOTTIDS, whose uteri are greatly expanded w/developing eggs
Phylum mollusca
includes 50,000 known species, ranks second only to the anthropds in terms of diversity.
Included animals:
snails, slugs, clams, scallops, squid, octupus, etc...
The Mollusca, together w/Annelids and Arthropods are PROTOSTOMES, which possess DORSALLY LOCATED HEARTS and VENTRALY LOCATED NERVE CORDS, the sharing of these characteristics indicates that they are closely related to each other.
Mollusca show further affinity to the annelids in the occurrence of TROCHOPHORE LARVAE in both phyla.

Characteristics binding all Molluscs:
1) muscular FOOT, generally used for locomotion and has been modified into arms and tentacles in one class
2) a dorsal VISCERAL MASS
3) well developed HEAD
4) most molluscs possess a rigid calcium carbonate SHELL
5) the dorsal portion of the visceral mass is specialized into the MANTLE, which is a fleshy layer that secretes the shell and also forms an invaginated space called the MANTLE CAVITY
6) THE MANTLE CAVITY carries the GILLS and the opening of the reproductive, excretory and digestive systems.
7) molluscan head is typically equipped w/numerous sensory organs, including image forming eyes, and well developed chemo- and touch receptors.
8) the MOUTH is usually equipped w/a resping RADULA - a belt of scraping teeth that is used to scrape food off surfaces.
9) most molluscs possess OPEN CIRCULATORY SYSTEMS, where a muscular heart pumps body fluids through blood vessels that open into spaces called sinuses.
10) the fluid is called HEMOLYMPH, NOT BLOOD

**Members of the Phylum Mollusca are normally divided into sven or eight different classes, we'll focus on five.
5 Phylum Mollusca classes we'll study
1) Class Monoplacophora: KNOW the general structure of the NEOPILINA
2) Class Polyplacophora: (=Class Amphineura) includes the CHITONS, which are all marine, and are characterized by having EIGHT CHEVRON-SHAPED SHELLS that overlap in a shingle-like fashion. This primitive group shows a lesse degree of cephalization than most other classes. They are RADULA feeders, and commonly seen in tide-pools
3) Class Gastropoda: largest class of phylum mollusca, includes SNAILS, SLUGS, LIMPETS AND OTHERS, all of which possess a SINGLE SHELL OR VALVE. Most forms are marine, some freshwater and terrestrial forms are common. Typical molluscan body, but the mantle cavite is in the anterior position and NOT the posterior, this rotation is known as TORSION, and is a distinctive gastropod occurrence, which is one reason most have a coiled shell. Some lack shells. Gastropods are radula feeders, scraping the surface of rocks, algae and plants for food.
4) Class Bivalia: (=Class Pelecypoda) includes forms w/2 halves to their SHELLS HINGED AT THE DORSAL MIDLINE, such as CLAMS, MUSSELS, OYSTERS, SCALLOPS.
BIVALVIA LACK RADULAE AND ARE INSTEAD FILTER FEEDERS. The gills of Bivalves are very large and occupy a mantle cavity that has been internalized between the partiatly opened valves and oever the gill surfaces by cilia. The mantle is modified to form an incurrent ans excurrent siphon, through which water is drawn through and expelled. The FOOT is wedge-like and is used to pull the animal through sediment. Strong adductor muscles can close the two valves to protect the animals from predators.
5) Class Cephalopoda: the MOST ADVANCED members of ALL THE INVERTEBRATE ANIMALS, the most obvious difference is the fact that cepholopods are ACTIVE, PREDATORY SWIMMERS - a lifestyle that has influenced EVERY aspect of these animals. As predators they have evolved very ACUTE SENSORY SYSTEMS including image-forming eyes that are similar to a humans (a case of CONVERGENT EVOLUTION), higher brain capacity to outwit their prey and grasping arms and tentacles. This group can be trains to recognized shapes and push appropriate buttons for food rewards. As fast swimmers, their BODIES HAVE BECOME VERY STREAMLINE, their SHELLS HAVE BEEN GREATLY REDUCED (lost entirely in some) to lighten their bodies, and their foot has become modified into a siphon used in JET PROPULSION - a mode of locomotion that is unique among the entire Animal Kingdom.

a common squid from the Phylum Mollusca and Class Cephalopoda.

The arms, tentacles and mouth are ventral (bottom), while the tip of the mantle is the dorsal (top) end of the body. The siphon lies on the posterior (rear) side of the animal, while the fins come off the anterior (front) side of the body. CONFUSION arises as the squid swims w/dorsal end first w/their anterior sides facing up.
The color of the animal's body is from specialized cells called CHROMATOPHOERES found just below the epithelium. These cells are muscle cells that contract,darkening the skin. Relaxation allows the chromatophores to retract and lighten the skin. They are masters at changing their color shades, especially during mating and fighting, from prey or predators.

Observed characteristics:
1) Ink sac, silver color
2) reproductive organs:
a) yellow-green OVARY
B) white- TESTIS dorsal portion of the body, where the ovaries of female sit, and no nidamental glands
3) ventral to the ovary and dorsal lies two large solid white, oval structures called the NIDAMENTAL GLANDS, which serve to add yolk to the eggs and surround them w/a capsule as they are laid.
Defining characteristics of Squids Anatomy and there uses
1) INK SAC: used to confuse predators, it will discharge a cloud of ink through its siphon. The predator will ofter attack the ink cloud while the squid escapes. Their is evidence that the ink may alos dull some senses of the fish predator
2) female sex determination: the dorsal end of the body will be filled w/a large transparent or yellow-green OVARY. Sometimes the ovary will have small spheres w/in it- these are developing eggs.
3) ventral to the ovary and dorsal to the ink sac lay two large solid white oval structures called, NIDAMENTAL GLANDS, which serve to add yolk to the eggs and to surround them w/a capsule as they are laid.
4) Male Sex Organs: located will be a single white TESTIS in the dorsal portion of the body, where the ovaries of females sit and NO nidamental glands.
5) the CAECUM, another white structure that lies next to the testis
6) KIDNEY, located just dorsal to the ink sac, thin-walled and usually identifiable by the tan fluid seen within.
7) held in side the kidney, NEPHRIDIA, molluscs rid their bodies of nitrogenous wastes by means of these, which are packed together in the kidney
8) GILLS, feathery looking, lying lateral to the other organs, with many small branches increasing the surface area to maximize the diffusion of Oxygen and Carbo Dioxide.
9) at the doral end of the gills lies thin walled BRANCHIAL HEARTS which are best id by the faint yellow or tan color of the blood w/in them
10) between the 2 branchial hearts lie the diamond shaped SYSTEMIC HEART this heart supplies blood to all the tissues of the body, while branchial hearts (branchial refers to gills) provide a pressure boost to push the blood more throught he tiny blood vessels of the highly branched gills
11) CLOSED CIRCULATORY SYSTEMS are unique in the cephalopods, which means blood travels strictly in blood vessels

13) off the dorsal end of the siphon, located the two long SIPHON RETRACTOR MUSCLES
14) ventral to the above muscle, on the oposterior face of the siphon itself, located are two thin ridges called PALLIAL CARTILAGES, they help to close up the mantle collar, forcing water to exit by way of the siphon
15) ANUS, located next to the ink sac on the animals right side
16) ESOPHAGUS, narrow tube that carries food from mouth to the stomach
17) anterior to the esophagus is a large white DIGESTIVE GLAND often called the LIVER
18) smalller digestive gland, sometimes called the PANCREAS, situated at the dorsal end of the first digestive gland
19) the esophagus opens up to the STOMACH, which is continuous w/the much larger CAECUM, a thin-walled sac that is usually filled w/white food matter
* in males the caecum fills the dorsal portion of the body together w/the testis

** In females the large ovary often displaces the stomach and caecum, and nutrients are absorbed by the caecum and the INTESTINE.

Eucoelomate Bilarteria
Members include: molluscs, annelids, arthropods

This group like all true coelomates has internal body cavities that are completely lined w/tissues derived from the mesoderm and the organs w/in the coelom are suspended by mesenteries
Phylum Annelids
this grouo includes the segemnted worms, such as the common earthworm

These worms are PROTOSTOMES, like the molluscs and anthropods. Adult protostomes also possess DORSALLY LOCATED HEARTS and VENTRALLY LOCATED CORDS.


The walls of each segment include circular and longitudinal muscle bands that can contract against the fluid filled segement of the coelom. These bands are aligned w/the HYDROSTATIC SKELETON to shorten and flatten versus lengthen and thin the segments. This body style gives the annelids much more control of their bodies, b/c EACH SEMENT CAN CHANGE SHAPE INDEPENDENTLY.

** ANNELIDS HAVE A CLOSED CIRCULATORY SYSTEM, which means that blood is remained only in the blood vessels. Gases, nutrients, wastes are exchanged between blood and tissues by SIMPLE DIFFUSION through the walls of the smallest blood vessels called CAPILLARIES.
Body structure of Annelids
They have a slender body shape, VERIFORM SHAPE. This shape provides a RELATIVELY HIGH SURFACE AREA-TO-VOLUME RATIO, some annelids lack speciealized respiratory surface other than the general skin surface, but manu do possess surface elaborations to further increase their surface areas.
3 major classes of Annelids
1) Largest class is the CLASS POLYCHAETA, which is made up of numerous bottom dwelling & free-swimming marine worms
2) CLASS OLIGOCHAETA includes the terrestrial earthworms, many freshwater, some marine worms.
3) CLASS HIRUDINEA includes ectoparasites, scavengers and carnivores commonly known as the LEECHES. Most are fresshwater, some marine and terrestrial
CLass Polychaeta
from the Phylum Annelida are segmented worms.

Polychaete = many spines

Characteristics: Most polychaete worms poseess a pair of thin extension coming off each segment called PARAPODIA, used in assisting locomotion to grip the substrate, assisted by the presence of numerous SETAE or chitinous spines on each parapodium. These appendages are highly vascularized and important sites of gas exchange.

Most polychaetas are bottom dwellers, crasling on of through the sand, and amny live in tubes formed in the substrate

Reproduction: varies from species to species, but MOST are DIOECIOUS and have TROCHOPHORE LARVAE, most do NOT possess permanent gonads - they tend to only develop gonads during reproductive periods.
from the Class Polychaeta, which is the CLAM WORM or PILE WORM that is common off our coast and familiar to fisherman as bait.

Body structure:
1) SETAE are present onthe sides
2) well developed heads
3) PERISTOMIUM, which is the first true segment that surrounds the mouth
4) PROSTOMIUM - not a ture segment for it DOESNOT possess any coelom, this is a fleshy triangular mass
5) PALPS, specialized sensory structure located on the prostomium
6) ANTERIOR TENTACLES, sensory structure located on the prostomium
7) eyes: 2 pairs on the dorsal
8) Pharynx, located w/in the mouth, which is equipped w/a pair of large JAWS that are effective in grapping prey items
from the Phylum Annelida, includes mostly terrestrial earthworms
from the Class Oligochaeta, an earthworm

Movement system: FILL IN NAME HERE, but they coordinate waves of alternating longitudinal versus circular muscle contractions called....? (fill in name here)**

Movement noises are created by the SETAE, which are short appendages that assist in locomotion along w/parapodia.

CUTICLE are slightl iridescence of the body surface, they help slow the rate of water loss through the skin
External anatomy of the Lumbricus, Class Oligochaeta
they have LONG VERIFORM BODY, this structure os formally called, CITELLUM, secretes a cocoon in which fertilized eggs are deposited.

On the anterior end:
1) mouth
2) PERISTOMIUM, the first two body segments
3) PROSTOMIUM: overhangs the mouth
4) ANUS: terminal posterior segment
5) PERISTOMIUM is identified by paying attention to the numbering of the anterior segments

** Oligochaeta are generally MONOECIOUS
1) a pair of MALE REPRODUCTIVE PORES by whch sperm exists in the body can be seen on the ventral surface of SEGMENT XV
3) FEMALE ORGANS: a small pair of FEMALE REPRODUCTIVE PORES exist by whch eggs exit the body, which is visible on SEGMENT XIV.

** BETWEEN SEGMENT IX, X AND XI are two pairs of small OPENINGS TO THE SEMINAL RECEPTACLES, sperm swim during copulation here.
Internal anatomy of the earthworm from Class Oligochaeta, Phylum Annelida
DORSAL BLOOD VESSELS is a dark line that runs down the middle of the body, inside the dorsal body wall. This vessel does play an important role in the pumping of the blood, which are simply modifies blood vessels w/much thicker muscular walls.

Both Oligochaeta and Polychaetes possess segmented coeloms, that are separated by membrane SEPTA that prevent from folding the body wallback. The septa requires you to PEEL the body wall back from region to region.
Digestive system of the Class Oligochaeta, earthworm from the Phylum Annelida
they have a more advanced digestive system that is subdivided into numerous specialized organs that divide the labors of digestion.

Organic materials are digested and absorbed, which are later defecated as soil CASTINGS.

Soil passes into the mouth and through a short BUCCAL CAVITY to a PHARYNX, that both look "fuzzy", b/c they are surrounded by radiating DILATOR MUSCLES that attach to the inner body wall, contract and stretch the pharynx and buccal cavity, creating suction to draw in soil.

Food is swallowed through as ESOPHAGUS by contractions, the esophagus delivers food to a larger, thin -walled CROP for storage, then its passed to the thicker walled, lighter appearing GIZZARD where it is grinds the food and then passes it into the INTESTINE where it is chemically digested and absorbed

Intestine is obscurred by masses of mustard-yellow tissue called CHLOROGOGUE TISSUE, which is very similar to our own "liver: as to the functions, undigested materials are then defecated out the terminal ANUS.
Circulatory system of the earthworm, Class Oligochaeta from Phylum Annelida
Surrounding much of the esophagus are FIVE PARIS OF HEARTS or AORTIC ARCHES, which are located dorsally. They will generally be VERY bright red due to the hemoglobin of the inclosed blood. Pumping occurs by peristalsis, just as it does in the dorsal blood vessels. Blood travels down in a posterior direction through the dorsal vessesl, which branched out by small arteries in each segment.

After traveling through the tissue of each segment, blood then collects in a ventral blood vessel back to the hearts. Passive valves inside the blood vessesl and hearts prevent the blood from backwards and ensures efficient blood circulation through the body
Reproducting Systems in earthworms of the Class Oligochaeta from Phylum Annelida
Oligochaetes almost always cross fertilize by mating w/other individuals. Visible organs present are a pair of large, three-lobed SEMINAL VESICLES which are centered somewhere around SEGMENT X, sperm is kept w/in these male reproductive organs until they are released during copulation. Also, present are the SMALLER, SPHERICAL SEMINAL RECEPTACLES of the female reproductive system, which serve to recieve sperm from a the males and store them until needed to fertilize the eggs, they are lying in SEGMENTS IX and X.
In males, two pair of TESTES, imbedded in the floor of the seminal vessicles at the junctures of segments IX, X, XI, they are very small white spheres.

Posterior to each testis is a SPERM FUNNEL, pleated like a fan it collect sperm released from the testes.

Posterior to the above is a coiled VAS DEFERENS that fuse and continua posteriorly to the male genital pore of segment XV

In females, Posterior to the ovaries, segment XIV, are EGG FUNNELS, they collect the eggs and deposit them through the female genital opening, which both the sperm and eggs are released from the appropriate gonads into the coelom and are swept to the respective funnels by the cilia.
How earthworms are created
Copulating earthworms meet anterior end first and overlap the anterior thirds of their bodies. The clitellum of each worm secretes a thick coating of mucous, which envelopes both worms. Sperm are released from each worm, and swim along ventral grooves of the external body wall to the seminal receptacle openings of the opposite worm. the worms then separate and they each fertilize their own eggs with the sperm stored in the seminal receptacles. This inlvolved the clitellum again, which secretes a nutrient-rich mucous this time, into which fertilized eggs are discharged from the egg funnel. the mucous sheath slides over the worm towards the anterior end. As the mucous sheath passes over segments IX, X, XI sperm are released from the seminal receptacles and fertilization occurs w/in the mucous sheath. The worm then completely slides out of the mucous, which then dries to form a cocoon.
Nervous system of earthworm's of Class Oligochaeta, from Phylum Annelida
anterior end is locates the SUPRAPHARYNGEAL GANGLIA, which makes up the BRAIN on the dorsal surface of the pharynx.

Following the brain around each side of the pharynx are nerve cords that wrap around the pharynx as CIRCUMPHARYNGLEAL CONNECTIVES, they meet ventrally and form a pair of smaller and harder to identify SUBPHARYNGEAL GANGLIA, posterior to them the nerve cords fuse down the entire length of the animal as the ventral nerve cord.
Excretory Systems of earthworms form Phylum Annelida
Primary excretory organs of annelids are the NEPHRIDIA, which are tubular structures that FILTER METABOLIC WASTES FROM THE COLOMIC FLUID. A funnel shaped opening of each nephridium called the NEPHROSTOME projects through the septum into the nest anterior segment. Cilia draw colomic fluid into the nephostome and into a long coiled TUBULAR PORTION of the nephridium, they are loaded w/active transport proteins, pump additional wastes from the tubule lumen back into the coelom, which then empties through an opening on the ventral body wall called the NEPHRIDIOPORE.

Nephridia are thin, white coiled tubules, usually w/very thin blood vessels visible on their surfaces.

In addition, to the nephridia, earthworms also possess excretory glands called CALCIFEROUS GLANDS, which rid the body of excess calcium that is abundant in the soils diets of earthworms. These glands form as evaginations of the esophagus and are located just beneath the hearts
Earthworm cross-section slide
Internal to the CUTICLE is the epidermal layer that secreted the cuticle, which is reffered to as a HYPODERMIS.

Extending through the hypodermis and cuticles are SETAE, which are thin and amy be missed in the slides

Below the hypodermis, muscle layers of the body wall- an OUTER CIRCULAR MUSCLE LAYER and an INNER LONGITUDINAL MUSCLE LAYER, which is covered w/the lining of the coelom and is called the PARIETAL PERITONEUM.

Internal organs are also covered w/a thin peritoneal covering called the VISCERAL PERITNEUM, NOT EASY TO ID IN SLIDES

Cross sections and oblique sections through portions of the NEPHRIDIA, located in the center of the coelom is the INTESTINE, which is suspended from the dorsal and ventral body walls by MESENTERIES.

W/in the dorsal and ventral mesenteries are located the cross-section DORSAL AND VENTRAL BLOOD VESSELS

Available is the ventral nerve cord, which is a single nerve cord that is formed by the fusion of two parallel nerve cords.

Invagination is a ridge that runs down the entire lenght of the intestine and is called the TYPHLOSOLE, which serves to increase the inner surface area of the intestine so it can hold more transport proteind for efficient absorption of nutrients.

Surrounding the intestine and penetrating the typhlosole is CHLOROGOGUE TISUE.

CIRCULAR AND LONGITUDINAL MUSCLE LAYERS are present as well as the intestines epithelial lining
Class Hirudinea
these are LEECHES, specialized ectoparasotes of vertebrate animals, many are scavengers, some are predators of small invertebrates at the bottoms of streams and ponds. Most are fresh water forms.

Leeches generally have DORSO-VENTRALLY FLATTENED BODIES w/numerous extermal rings encirling the body called ANNULI. Several annuli occur per segment, giving the appearance of many more segments than actually occur. The ANTERIOR AND POSTERIOR END ARE EQUIPPED W/SUCKERS surrounding the mouth and anus, respectively used to attach to prey. In the mouth are sharp razor-like teeth that painlessly slice open the skin of prey. The pherynx expands by dilator muscles as in Oligochates to suck in blood. Leeches stay attached to their prey for relatively short periods of time, in which they do not normally kill their prey.

They differ from other annelids in that they generally LACK SETAE AND INTERNAL BODY SEPTA. The BODY CAVITY IS MOSTLY FILLED W/CONNECTIVE TISSUE.

Locomotion is NOT done by peristalsis, instead they use their body wall muscles and suckers to MOVE ABOUT IN A LOOPING OF INCHWORM FASHION.

The intestines of leeches are convuluted w/many extensive CAECAE, that swell and hold large amounts of blood - the main food of parasitic forms
Parietal Peritoneum is located in what organism, class, phylum and where?
Peritoneum is located in an earthworm, Class Oligochaeta, Phylum Annelida-it is a thin epithelial lining of the coelom, which separates the body cavity from the inner Longitudinal muscle layer or the (epidermis and muscles).
Coelom in an earthworm is located where, class, phylum, what is it used for?
Coelom- the body cavity (fluid-filled in the living worm) in the Class Oligochaeta, Phylum Annelida.
What is the infolding of the dorsal seuface of the intestine called? class? Phylum? What is the specifc function of this part?
Intestine - Note the infolding of the dorsal surface of the intestine. This is called the typhlosole,

What is the specific function of the typhlosole?
What are the cells surrounding the exterior surface of the intestine called, class, phylum?
They are called chloragogue cells. They function as: an accessory digestive gland; the site of glycogen synthesis, deamination of proteins, and production of ammonia and urea
Setae- 2 pairs ventrally and two pairs ventrolaterally projecting from the body wall.