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33 Cards in this Set
- Front
- Back
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What are the (7) characteristics of chordates?
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o 1. Hallow, dorsal, nerve chord
o 2. Notochord • supporting rod o 3. Pharyngeal slits at sometime in development • slits in pharynx, passageway in throat, appear in mammal embryology o big three occur at some time during development o 4. Cells that bind iodine to protein (endostyle or thyroid gland) o 5. Heart that pumps blood ventrally in the anterior direction o 6. Post anal tail o 7. Segmented • not uniqure to chordates, but all chordates are segmented |
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What kinda of animals show chordate characteristics?
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• Phylum Chordata
Subphylum Craniata (Vertebrata) • Includes animals with backbones and a few without (Hagfish) Sunphylum Cephalochrodata • Notochord goes all the way to the anterior tip • Branchiostoma (genus name); Amphioxus (common name) “lancolets” Subphylum Urochordata • Turnicates or sea squirts notochord and nerve chord tail for larvae Cephalochordates and Urochordates often called protochordates often called protochordates |
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How did chordates arise?
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o Deuterostomes
• Phylum Hemichordata- “half chordates” acorn worms • Phylum Echonodermata- “spiny skin” star fish, sea cucumbers, sand dollars, sea urchins • Lack chordate characteristics, but show their affinities in other ways |
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What are characteristics of amphioxus?
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o In long, pointed, muscular, found in water
o Cephalochordata subphylum o 1. Lifestyle • marine, bottom dwellers o 2. Locomotion • swimming- segmented muscles • burrowing- muscles/notochord used to burrow o 3. Feeding mouth • large • bucal or oral- cirri- sensory- mechanism and chemicals to reject materials • wheel organ cilia H2O current created • H2O through mouth/larynx o 4. Circulation • similar to vertebrates blood flow into the sinus venosus • does not beat • blood collecting organ “sac” • anterior in ventral aorta o forward beneath pharynx o vessels don’t show up in presented specimens o dorsally in many branchial arteries • pulsates at bases and forces blood up • • • o 2 dorsal aortas • fuse to form single dorsal aorta • Branches- myomers and body organs o Veins collect and return blood to sinus venosus o 5. Respiration • skin and across pharynx • no gills (not especially across pharynx • pharynx used primarily for feeding o Has pharyngeal slits, hallow dorsal n.c. (no brain), notochord o Swims o Locomotory system like vertebrates • Because of segmented musculature o Post anal tail o Circulatory system which is vertebrate like o Equivalent of vertebrate thyroid and liver |
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What are characteristics of adult tunicates?
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• Subphylum Urochordata (or Tunicata)
• Adult “sea squirt” o 1. Lifestyle- marine, adults, mostly sessile (attached to group; don’t move) • two groups aren’t sessile • tunic made out of tunicin similar to plants- cellulose o 2. Feeding- • incurrent siphon into pharynx lined with cilia • food retained in gut • water out pharyngeal slits into the atrium • endostyle makes mucous, cells that bind binds iodine to protein • food moves through the gut anus opens into the atrium Atrium • Water from pharynx • Waste from gut Eggs and sperm from gonads • All to sea through excurrent siphon |
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What are characteristics of tunicate larva?
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more informative than adult
o Tadpole (body and tail) swims o Tail (post-anal) containing notochord, nerve chord (above notochord) muscles cells, and segmented bodies o N.C., hallow, dorsal enlarged at anterior • Brain ocellus (light) and statocyst (position) o Has pharyngeal slits, but does not feed • Metamorphosis o Settles on head, tail shortens/ absorbs o Chordate characteristics were in tail hence why larval stage is more informative o Larvace • Stay as larva, very small • Oikoplenra (larvacean tunciate) has had its genome sequence |
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What are characteristics of acorn worms?
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• Phylum Hemichordata “half chordate”
o Acorn worms- enteropneusts (gut nose) • More intertebrate characteristics than chordates • 3 parts proboscis, collar, trunk o Feeding • Mouth Feeds via cilliary current into mouth • Anterior boundary of collar o Sweep food, water, sand in o Water out through slits behind collar • Blood flow Opposite to vertebrates Flows posteriorly in ventral vessel • Chordate like characteristics Pharyngeal gill slits Hallow dorsal nc in collar • But, solid ventral nc • And a nerve net Stomochord like notochord • Most likely not the same |
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What is the historical evolutionary origin of chordate line?
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Evolutionary origin of chordate line
• Difficult to trace- few fossils • Protochordates lack backbone, any bones, teeth o Therefore no fossil evidence o Area of interest today • Burgess Shale in Canada Calcichordates • Related to echinodermas • Recent years- fossils from China Haikonella • Looks like amphioxus, but eyes present o More brain and cephalization (brain development) o Transition from invertebrates |
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What is the evolutionary sequence from echinoderm-like ancestor/ hemichordate-like ancestor?
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• Tunicate-like ancestor
• Sea lilies or crinoids- stalked, sessile o Probably ciliated arms gathered food (filter feeder) o Pharyngeal slits • Advantageous o Sea lilies could get pharyngeal slits • Ciliary currents bring in food • Pharyngeal slits persist (hemichordate-like) • From this, tunicate like animals could have evolved Tunicate larva is the life stage to big three and muscle in tail Could larvae for have been ancestral to chordate line |
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What is heterochrony?
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Heterochrony
• Genetic shift in the timing of development of a body part relative to the ancestral condition • May involve different growth rate between reproductive organs and rest of body o Sexually mature organism with juvenile appearance |
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What is paedomorphosis?
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Paedomorphosis “juvenile form”
• Retention of juvenile characters into reproductive state • Two ways to have juvenile characters and still reproduce progenesis and neotony |
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What is progenesis?
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Progenesis (gonads mature early)
• early sexual maturation in an immature individual |
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What is neotony?
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o 2. Neotony (delayed somatic changes)
• mature animal never shed juvenile traits • both are sexually mature with appearance of a juvenile • Tunicate larvae could have been sexually mature as a result of a heterochronic shift • Hence the evolution of chordates |
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How are organisms grouped together?
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Organisms are groups together on basis of homologies
• Homologous traits are traits that share a common ancestry • New characters are called a “derived trait” or “apomorphic trait” • Synapomorphy o A shared apomorphic trait • Shared by ancestor and all descendents |
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What are characteristics of triploblastic animals?
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o 3 primary embryonic germ layers
• outer layer- ectoderm epidermis, nervous system, lining of mouth and anus • inner layer- endoderm lining of gut, organs that form from gut (lung, liver, gall bladder) • middle layer- mesoderm bones, muscles, heart kidneys • occurrence and importance of mesoderms jelly fish, ctenophores (comb jelly) • diploblastic, 2 layers, no mesoderms flatworms (planaria) and rest of phyla • triploblastic, 3 layers • mesoderm forms during embryology outpouching of gut (deuterostomes) • may be modified o especially by the presence of yolk cell that are set aside early and form blocks of tissue first (protostomes) flatworm o acoelomate • coelomate animals o annelids, mollusks, crustaceans, starfish, chordates (amphioxus to humans) • spaces or cavities form in mesoderm o coelom (paritneal cavity) • allows organs to move (digestive tracts, heart, lungs) independent of your body wall • space surrounded by mesoderm |
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What are protostome characteristics?
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• Mouth blastopore derivative
• Spiral (lie in furrows) and determinante (splitting would give two partial individuals) cleavage • Mesoderm formation from specific cells as blocks of tissue • Schizocoelic (split in the mesoderm) coelom formation • Trochophore-like larva |
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What are deuterostome characteristics?
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• Anus blastopore derivative, invagination forms mouth
• Radial (lie directly above) and regulatory (splitting gives two complete individuals) cleavage • Mesoderm formation from outpouching of gut wall • Enterocoelic (outpouching of the gut) coelom formation • Bipinnaria-like larva |
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What are the characteristics of cyclostomes?
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o Cyclostomes (round mouth)
• Lampreys and hag fish • Round mouth because jawless cannot open and close |
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What are the characteristics of lampreys?
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• Lampreys
About 10 species Marine and freshwater Most go upstream to breed Shed gametes upstream and die Larva • Ammocetes were thought to be a different species at first • Very different than the adult • They stay larva for 6-8 years • Metamorphosis o Migrate to ocean or lake • Brook lamprey stay in the stream, non parasitic Feeding • Most a parasitic • Horny teeth made out of keratin o Rasp off flesh • Creates a suction by pulling tongue back Respiration • Water • When feeding, water does in and out through the gill openings “tidal” • Gill pouches lined with gill filaments Endoskeleton • Cartilage, but no bone • Loss of bone may be secondary • Notochord • Archalia- segmented o Cartilage o Lie laterally to nerve cord and notochord o Probably homologous to vertebrae Economic impact on Great Lakes • Huge • Welland Canal 1929 o Opened St Lawrence river to Superior • By 1946, lampreys move into superior o Destroyed fisheries, but coming back now |
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What are the characteristics of ammocetes?
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Greater cephalization than amphioxus
• 3 pt brain • sense organs: light receptors, otic vesicles, and olfactory sac Muscles and gills associated with pharynx • pumps a water current than pharynx Heart pumps blood Two are very alike, amphioxus to ammocetes to craniates |
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What are the characteristics of Hagfish?
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• Hagfish- Myxini group
Marine Jawless agnathans Bottom feeding scavengers Small soft invertebrates Dead fish Short, tentacle-like papillae around mouth Two rasping plates Single nostril to pharynx • Uses water for respiration • Flows in nostril to pharynx and out pharengeal slits Eyes • Vestigial, covered with skin Muscus • Able to produce copious amounts mucus Hagfish “myxini” nasal slime • No trace of bone, no archalia • Chraniata but not vertebrata • Probable sister group of lampreys • Probably more related than previously thought o Molecular evidence o Evidence from neural crest cells o Anatomy • Both are agnathans and cyclostomes |
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What are the characteristics of ostracoderms?
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• Extinct, small 2-3 cm
• Artificial grouping, no taxonomic status • Several different ancestors • Polyphyletic group Does not contain most recent common ancestor • One group close to lampreys • Characteristics Lack jaws Were very successful Bones plates are larger at the anterior bone Perhaps originated to ostracoderms • Cosmoid plates or scales • Bone underneath • Thin layer of dentin • Covered with thin enamel layer Heavy bodied • Probably moved along bottom scooping food off food Most lacked paired fins • Some anterior pair of stabilizers Had some endochondral bone in head Tail two lobes 1 small one large • Larger lower lobe- hypocercal tail • Larger upper lobe- heterocercal Probably oldest fish- all extinct |
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What is Evolution?
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change in gene frequencies over time in a population of organisms
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what is an Adaptation?
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• A trait that has come to be at higher frequencies in a population because it confers a greater probability of success in the prevailing environment than an available alternative trait
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What is a phylogeny?
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• Classification system for grouping animals
o Based on evolutionary relationship • Modifiable hypothesis • Based on the presence of homologous structures in organisms o Structures that have a common origin, that can be traced back to a common ancestral precursor • May or may not have the same functions |
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How are organisms classified in taxonomy?
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• Organisms grouped together based on relatedness
o Kingdon, phylum, class, order, family, genus, species • King phillip came over from Greece to spain • Species Group or population or organisms capable of interbreeding and producing fertile offspring • Like species are grouped into one genus • Binomial name of the organism Combines genus and species names • greywolf Canus lupus • coyote Canus latrans • phylum group related by body plan one phylum usually because distinguished from other phyla because their body plans differ |
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What are homologous characters?
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• homologous characters
arise from the same characters in a common ancestor • horseleg, human hand, bird wing, bat wing most specify as homologous of what • all are homologous limbs • all arose from the limb of a fish wings of birds and wings of bats • not homologous wings • arose from different ancestors • relationship of groups (clades) of animals based on homologies “free floating” term |
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How are homologous characters described?
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• 1. Derived characters diagnose a group
Mammals • Hair, 3 ear ossicles, lower jaw with one dentary bone, mammary glands o Separates them from reptiles o Characters are derived, or advanced, or apomorphic • 2. Primitive or ancestral or pleisiomorphic characters evolved in a more distant time more widespread found in more groups not helpful in determining phylogenies/homology |
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What is cladistic phylogeny?
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o Based on shared apomorphic derived characteristics- synapomorphies
• Homologous with one another • Homoplastic traits Similarities due to any cause other than common ancestry • May result from convergent evolution • Not helpful in terms of creating phylogenies o Analogous |
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What are synapomorphies of the subphylum craniata?
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o Traits unique to craniates (apomorphic/derived traits)
o 1. Braincase o 2. Enlarged 3 part brain o 3. Complex sense organs (otic, optic, olfactory) cephilization or specialized head region o 4. Neural crest cells • Migratory cells that leave the developing nc o 5. Placode • area of embryonic ectoderm thickening that gives rise to neural structures in adults |
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What are the components of cladograms?
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o In group
• Clade of interest o Sister group • Immediate outgroup sharing common ancestor and clade of interest o Out group • Outside the clade of interest o Most phylogenies put hagfish outside of the vertebral clade but within the craniate clade |
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What are characteristics of Chondrichthyes?
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Class Chondrichthyes (cartilage fish)
• Subclass Elasmobranchii- sharks, skates, and rays, sawfish “plate gills” • Subclass Holocephali- chimaeras • 1. Internal skeleton- cartilage o parts may calcify/ become hard, but not bone o only bone in scales and teeth • loss of bone is secondary o extant forms • vertebrae with cartilaginous vertebral centrum • 2. Jaws- formed by mandibular arch o no bony plates contribute o first gill pouch spiracle (may be lost completely) • 3. Scales o if present, small placoid o very toothlike: boney base, pulp cavity, covered with dentine, enamel • 4. No lungs or swim bladder o heavier than water- tend to star near the bottom • 5. Primarily marine • 6. Heterocercal tails • 7. Males have claspers for sperm transfer o pelvic fin o come together to makes a tube • 8. Fertilization usually internal o small number of offspring • 9. Embryos are protected |
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What are ways in which embryos are protected?
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o species may be
• oviparous egg laying (bird) large yolky egg in protective case development occurs outside mothers body skate egg case- mermaids purse • viviparous fertilized egg retained in body of female young bone alive (mammals) nutrients are transferred from body of mother to offspring (some sharks) • ovovivipary yolky fertilized egg is retained in the body of the female • young develop in a uterous and born alive • embryo is nourished by its own yolk • protected by mother’s body, but nourishment comes from yolk |
