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55 Cards in this Set

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  • Back
What are some characteristics of the phylum Porifera? 6 of them.
-multicellular animals
-relatively simple structure which lack true tissues and organs
-cells of porifera are fairly independant
-varies in size
-could have radial symmetry...
-but most are irregular encrusting or branching forms.
What sponge body plan group does Leucosolenia belong to?
-belongs to the asconoid sponge group

**ie: very simple, no folding**
Describe the body of Leucosolenia.
-body consists of whitish horizontal tubes which have upright branches
-each upright branch is considered to ba an individual sponge.
What is an Osculum?
-an opening on the distal end of the sponge
-is the excurrent or exhalent opening of the sponge body where water exits out of the body
How do Leucosolenia colonies form?
-by Asexual External Budding
-buds are at the base of some individuals
What is Ostia? (for leucosolenia)
-microscopic pores all over the body which allow water to enter
-ostia is an intracellular canal within a single cell called a porocyte
What is a Porocyte?
-cells with pores in them that allow water through
-porocyte can open or close pores
-shaped like doughnuts
-pores are called ostia
What is the Spongocoel?
-a large central cavity where water ends up
What are pinacocytes?
-cells which cover the body of leucosolenia
-don't form a true epithelium because there is no lateral coherence and interdependency of cells
-pinacocytes can contract or expand to change the volume of the sponge (very minimal though)
What are choanocytes?
-cells lining the spongocoel in leucosolenia, radial canal in syconoids, and flagellated chambers of leuconoids
-main purpose is food capture and water movement
What are choanocytes composed of?
-Flagellum: causes water to move in the sponge

-Microvilli Collar: Captures food in the current created by the flagellum

-Base: made of cytoplasm, a nucleus, and vacoules.

**looks like a bomb with a fuse**
What is the Mesohyl?
-the mesohyl is the region between the pinacocytes and the choanocytes.
What is Mesohyl composed of?
-a skeleton of calcium carbonate spicules
What are Scleroblasts?
-amoeboid cells which secrete calcium carbonate spicules
What are archeocytes?
-amoebocytes that are phagocytic and are important in digestion

-may develope eggs
-archeocytes are wandering cells capable of differentiating into any number of cell types
What are Collencytes?
-amoebocytes that are involved in secreting the dispersed collagen fibers present in the mesohyl of all sponges
Describe the flow of water in Leucosolenia starting with flagellar action.
-flagellar action forces water out the osculum, decreasing the water pressure gradient
-therefore water is drawn in through the ostia
-cycle repeats
Why do more complex sponges have the tendancy to fold?
-folding increases the surface area of the sponge
-therefore they can have a sufficient surface area to volume ratio to ensure the sponge with enough nutrients
What sponge body plan group does Sycon belong to?
-belongs to the syconoid body plan

**ie: relatively simple body folding**
What do the spicules on sycon look like?
-they look like hair sticking out of fingerlike projections
What is the Radial Canal?
-the cavity on the inside of each fingerlike lobe
What are incurrent canals?
-the space between the finger like lobes
What is the difference between the ostia of sycon versus the ostia of leucosolenia?
-ostia of leucosolenia exists within the porocyte

-ostia of sycon is just the upper region between the fingerlike lobes. It can't open or close, it's just the space up there...
What are prosopyles?
-prosopyles are small pores in the fingerlike lobes that allow water to enter the radial canals.
-just a tubular penetration between the cells in the wall of the sponge

**sycons don't have porocytes**
What is the Apopyle?
-large pores at the base of the radial canal which allow water through to the spongocoel
Where are choanocytes found in sycon?
-choanocytes are limited to the walls of the radial canals
Where are pinacocytes found on sycon?
-pinacocytes are found lining the spongocoel and lining the outer surface of the body
Where are porocytes found on sycon?
How does sycon reproduce? Approx 10 steps.
1) They are hermaphroditic

2) Sperm is produced by archeocytes or choanocytes

3) Sperm is blasted through the osculum and released to the environment

4) Sperm enters the ostia/prosopyle of other sponges. Sperm is taken up by choanocytes.

5) Choanocytes with draw their collars, detach and move into the mesohyl looking for an egg cell

6) Eggs are fertilized in the mesohyl

7) Egg cleaves and developes into an

8) Amphiblastula develops flagella and move back to the radial canal, flow through the apopyle, into the spongocoel and out through the osculum

9) Flagellated amphiblastula exists in the environment as a freeswimming larvae

10) Eventually finds a place to attach themselves and they metamorph into sycon adults
What does the metamorphisis of an amphiblastula involve?
-the movement of smaller flagellated cells to the inside to form choanocytes
-the larger nonflagellated cells form pinacoderm
-choanocyte and pinacocyte layers produce amoebocytes
What is an amphiblastula larva?
-amphiblastula larva is hollow, many celled embryo
-one hemisphere is composed of small flagellated cells
-the other hemisphere is composed of large, non flagellated cells
What is parenchymula larva?
-parenchymula larva are solid, many celled embryo
-cells on the outside of the larva are flagellated

-when these larva settle, the external flagellated cells loose their flagella and migrate to the inside to form choanocytes and the interir cells move to the exterior to form pinacocytes
How are spicules formed in sycon?
-produced by 'scleroblasts'
-3 cells come together, then each cell divides, forming 6 cells
-3 cells are basal cells, 3 cells are apical cells
-1 basal + 1 apical = a single ray of the 3pronged spicule of sycon
-composed of calcium carbonate

**scleroblasts will then either die or change their function after forming spicules**
Describe the water flow in sycon.
-water flows......
-through the ostia into the incurrent canal
-through the prosopyle and into the radial canal (with shitloads of choanocytes)
-through the apopyle and into the spongocoel
-makes its way through the spongocoel and out the osculum
List the characteristics of the Class Hexactinellida.
-spicules have 6 rays
-live in the depths of the ocean
-the most individual members of the phylum porifera
-body plan complexity is somewhere in between that found in syconoids and leuconoids
-outer surface is covered by a dermal membrane but the body itself is largely 'syncytial'
-skeletons of some glass sponges are latticelike
Are leucosolenia or sycon colonial?
-both are colonial
List the characteristics of the Class Demospongia. approx 6 of them
-have siliceous spicules, spongin fibers, or a combination of the two
-if they have spicules, they are either monaxons or tetraxons.
-if spicules and spongin fibers are present, spicules are embedded in the fibers
-all Demospongia are *leuconoid*
-some are encrusting, some have upright branches, some form irregular mounds, some are stringlike(foliaceous), some are tubular and others are urn/goblet shaped
-they vary in color, and have huge depth ranges.
What are the 3 main subclasses to Demospongia?
1) Tetractinellida: spicules are tetraxons, skeletons are complex with several different types of spicules

2) Monaxida: have siliceous monaxon spicules, most abundant group

3) Keratosa: lack spicules, 100% spongin
What are the characteristics to the Family Spongillidae?
-belongs to the subclass Monasonida of the class Demospongia
-lives in freshwater (streams and ponds)
-fastened to reeds, rushes, submerged logs and rocks
-they are colonial
-vary in color from light green to yellowish brown
What are the main characteristics of leuconoids which seperate them from syconoids and ascanoids? 4 of them.
-leuconoids have the highest degree of body wall folding
-mesohyl layer is much thicker than ascanoids or syconoids
-leuconoids have a very modified spongocoel
-choanocytes are restricted to flagellated chambers (some sponges have up to 10,000 chambers/cubic mm
Describe the flow of water in the typical leuconoid sponge.
-through ostia, into subdermal chamber
-through incurrent canal, into flagellated chamber
-through apopyle, into excurrent canal
-through modified spongocoel and out through osculum
What are the 2 types of spicules in leuconoids?
-megascleres and microscleres

-microscleres are closer to the surface
-megascleres are scattered throughout
What are fascicles?
-bundles of megascleres

**some fascicles radiate outward to the surface, others form transverse braces**
What are gemmules?
-internal buds within leuconoids
-necessary for survival (ie: wintering)
-germinate in the spring into new sponges
What are overwintering bodies?
-overwintering bodies are a cluster of 2 or 3 gemmules
How do leuconoids control water flow?
-can regulate the size of the osculum by special cells called myocytes (lines the osculum like a band of circular muscle)

-central cells can regulate by shifting around and blocking the apopyle
How do leuconoids feed?
-fine filtration process (ie: outer pores, protoplasmic strands across the incurrent canals, etc.) ONLY FINE PARTICLES ARE FILTERED BY THE CHOANOCYTES IN THE FLAGELLATED CHAMBERS
-food is trapped in the collars of choanocytes, passed on to the body of choanocyte where it is engulfed
-passes the food to amoebocytes
-amoebocytes are the main sites of digestion
-amoebocytes and choanocytes are free to transfer particles to other cells
What are some characteristics of the Family Clionidae?
-they bore into calcareous structures such as coral and mollusc shells
What are some characteristics of sponges?
-can rearrange their internal structure when water currents are altered around them
-a single cell can regenerate into a new sponge
Draw and label leucosolenia.
Did you get...
-choanocyte (did you draw this properly?)
Draw and label a hemisected sycon.
Did you get...
-radial canal
Sketch a sycon amphiblastula.
Hope it looks nice!
Sketch the spicules of sycon and hexactinellid.
-sycon spicule has 3 spikes
-hexactinellied has 6 spikes
Sketch a gemmule
Look good?
Sketch a flagellated chamber. Then do one with a central cell.
Did you get...
-excurrent canal
-central cell