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43 Cards in this Set
- Front
- Back
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The position of vertebrates in the animal kingdom
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-Phylum Chordata
-The Deuterostome branch (with echinoderms and hemichordates) |
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4 mandatory traits of chordates
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-Notochord: support structure
-Dorsal, hollow nerve cord -Pharyngeal gill slits: not necessarily functional -Postanal tail |
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Name the 3 subphyla of Chordata
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-Urochordata
-Cephalochordata -Vertebrata |
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Subphylum Urochordata
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-"tail-chord"
-Represented by the tunicates, aka sea squirts -adults filter feed and squirt the filtered water out of an excurrent siphon |
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Subphylum Cephalochordata
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-Lancelets
-Notochord extends all the way up to the tip of the head, displacing the brain -This is an adaptation for their lifestyle of burrowing into fine sediments head-first. |
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Subphylum Vertebrata
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-"having vertebrae"
-The function of the notochord is generally replaced by a bony column made up of vertebrae (but still have a notochord at some point in their lives) |
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What is the problem of defining classes in Vertebrata?
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-The jury is still out on how exactly to categorize the different groups, whether it is lumping, splitting, etc.
-We will be using a more classical approach |
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Origin of vertebrates
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-Invertebrate ancestry (at least a close affinity genetically and anatomically speaking)
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Deuterostomes vs. Protostomes
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-Developmentally different
-Coeloms (internal cavities) develop differently -Deuterostomes (literally “second mouth”): Anus develops from blastopore. Radial (even, symmetrical), indeterminate (you can’t tell what each cell is going to become) cleavage. -Protostomes (literally “first mouth”): Mouth develops from blastopore. Spiral (uneven), determinate (you can tell what cell is going to become what) cleavage. |
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What are the two types of animal larvae?
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-Protostomes: trochophore
-Deuterostomes: tornaria (hemichordates), bipinnaria (echinoderms) -Except for vertebrates!! Vertebrates have something more “tadpole-like” in appearance |
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How did protostome groups compare to vertebrates?
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-Arthropods (hey, this is a successful phylum! Maybe they are more closely related to vertebrates!)
-Morphological similarities between primitive jawless fishes and primitive arthropods (Limulus) -But primitive arthropods have legs, and primitive jawless fishes don’t -Annelids -Vertebrate body plan similar to the upside-down body plan of an annelid -Lots of problems that are tougher to reconcile if you flip it upside-down. Ventral brain? Dorsal mouth? I don’t think so. |
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What is the vertebrates' closest deuterostome relative, and why?
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-Echinoderms
-Similar cleavage patterns, blastopore development, coelom formation, and larvae to hemichordates—support through DNA analyses -More similarities between us and this deuterostome branch than protostome branch -Common Deuterostome ancestor? -Still trying to figure out what it might be, if it exists... |
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What is the idea of Tunicate larva and Paedogenesis?
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-Paedogenesis: “acceleration of maturation.” Becoming sexually reproductive earlier than we had thought (even sometimes when showing juvenile characteristics).
1/23/08 -Maybe due to some mutation, genetic mistake, in which the larval stage becomes a sexually active organism, able to reproduce then and in essence never go to its adult stage. -Idea: over time, sessile arm feeder loses arms and becomes filter feeder with free swimming larva, then larva becomes sexually active, which eventually leads to fish. |
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What were the two types of the first fish?
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-Ostracoderms appear in Cambrian fossils
-Relatively large heads, primitive looking -Class Agnatha or Ostracodermi -Jawless, bony armor, many with bony endoskeleton -Most inhabited freshwater -Placoderms appear (and Ostracoderms disappear) in Devonian fossils -Class Placodermi -No living relatives, nothing alive today resembles them -Jaws, paired fins, bony armor and endoskeleton -Not directly ancestral to higher fishes -May have given rise to cartilaginous fishes (no real solid fossil proof showing relationships just yet) |
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What were the first Chondrichthyes?
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-Appeared in the late Devonian period (the same period as the Placoderms)
-Probably developed in freshwater! (Weird) -Differed from modern sharks -Terminal mouth at the tip of the snout, rather than on the underside of the head like modern sharks -Pectoral fins broadly joined to the body. Fins very immobile, no twisting ability in the fins because they are attached to the body completely on the inner edge. -No pelvic claspers for reproduction purposes |
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What are Skates & Rays, and what is the difference between them? When did they appear, and from what did they descend? How did the body shape come about?
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-Subclass Elasmobranchii (same as sharks)
-Skates are different from rays mainly by the thickness of the tail (thicker tails on rays) -Appeared in the Mesozoic -Descended from primitive sharks (rather than the other way around) -Odd body form is derived from the general shark body plan—an adaptation toward life on the sea floor. |
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What about the Chimaeras?
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-Subclass Holocephali
-Appeared shortly after primitive sharks, but did not arise from them -Not that closely related to either the sharks or the skates & rays. -Slightly different lineage, possibly arose independently from placoderms...? -Some people argue they shouldn’t even be in Chondrichthyes because of this. |
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What are the main groups of the first Osteichthyes?
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-Arose in the late Silurian
-Probably from freshwater -Followed two lines of development: -Sarcopterygii: fleshy-finned (aka lobe-finned), lungfishes, crossopterygians, coelocanths, primitive amphibians, etc. Important origin to all other non-fish vertebrates. -Actinopterygii: ray-finned, most other fish. |
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What are the Sarcopterygii?
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-Crossopterygii
-Lobe-finned fishes. Big wad of flesh at the base of the fin! Even has bony structure inside the fleshy part. -Ancestral to first amphibians -Tetrapod-like bones in lobe fins. Homologous to feet? -Thought extinct until 1939—coelocanth found in fish market near Indian Ocean. Local fishermen had been catching them all the time! -Dipnoi -Lungfishes. Air bladder modified into “lung!” -Peaked in Paleozoic, then declined -3 living genera: Australia, Africa, South America |
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What are the Actinopteygii?
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-Chondrostei
-Cartilaginous ganoids. Skeletal system starts off bony and becomes cartilaginous! Have hard, ganoid scales. -Paddlefish and Sturgeons -Became dominant during Paleozoic, then declined -Holostei -Bony ganoids. Still have hard, ganoid scales, but have internal bony skeleton. -Gars and Bowfin -Became dominant during the Mesozoic, then declined -Teleostei -Higher bony fishes -Common modern fishes -Became dominant during Cenozoic, still dominant |
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What are the general details of amphibians?
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-Arose from lobe-finned fishes
-Freshwater inhabitants -Appeared in the Devonian period -Cool adaptations: -Strong limbs for movement out of water! Could prop themselves up and even emerge from the water. -Lungs for breathing air -Interim survival adaptations for continued existence in water rather than on land. This was a period of drying, in which living in inland waters was a dangerous thing! It wasn’t “so they could go on land.” It was so they could survive! -Oldest group survived until Triassic -Another extinct before Mesozoic -Relationship to present day amphibians not clear -Little known about present groups -Anurans (frogs, toads) appeared in Triassic -Others (salamanders, etc.) appeared in Cretaceous |
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What are the general details of reptiles?
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-Appeared in Carboniferous period
-Branched quickly into two groups: -Subclass Anapsida – “stem reptiles”- thecodonts - reptile/bird ancestors. This is the group that gave rise to the reptiles and birds we know today. -Subclass Synapsida – “therapsids” – mammal ancestors. -Dominant vertebrates by the end of the Paleozoic -Turtles appeared at the end of the Paleozoic, haven’t really changed much in appearance. -Turtles are the oldest living group of reptiles. -We discovered that the duck-billed platypus is from around this time, too! -By the Mesozoic, it was the “age of the reptiles,” because they were so dominant and had the greatest diversity and abundance. -Lizards and snakes appeared in the Jurassic period -Very distantly related to turtles -Crocodilians descended from the Thecodonts -Closest living relatives (true reptiles) of dinosaurs!! -More closely related to birds than to other reptiles |
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What are the groups of dinosaurs?
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-Two groups
-Saurischian – reptile like – bipedal carnivores -The actual bird ancestors -Ornithischian – bird like – herbivores -Name based on the pelvic shape, but NOT the bird ancestors -Most of them died by the end of the Cretaceous period (nooooes) |
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What are things that people often call dinosaurs, but are not dinosaurs?
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-Plesiosaurs with snake-like neck and paddle-like limbs
-Nessie! -Part of the Therapsid group, so NOT a dinosaur. -Ichthyosaurs -Marine, dolphin-like -Pterosaurs -Membranous wings -Wingspread > 25 feet -NOT ANCESTRAL TO BIRDS! Didn’t come out of the thecodont group. -Remember: if they’re not dinosaurs, they’re not birds—they are reptiles. -Extinct by the end of the Cretaceous period |
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What are the general details of Birds?
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-Appeared in the Jurassic (yay!)
-Descendents of the thecodont reptiles (fairly certain due to the improving fossil record) -Archaeopteryx (literally “ancient-wing”) -Feathers, wing shape like modern birds -Reptilian teeth, claws, and tail (with vertebrae!) -Definitely capable of gliding, maybe capable of flying -Diversification during Tertiary -Most modern genera were present by the end of the Pliocene (end of the Tertiary) -Variation occurred very rapidly |
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What are the general details of mammals?
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-Legs tucked under rather than off to the sides, which brings the body higher up off the ground
-Developed from therapsid reptiles -Three major groups: Prototheria (Monotremes), Eutheria (Placentals), Metatheria (Marsupials) -One group gave rise to present day marsupials and placentals -Earliest mammals appeared in the late Triassic -Marsupials: Early cretaceous -Placentals: Slightly later -Monotremes: There is no evidence of these before the mid-Tertiary, but the expectation is that they would be more primitive than others because they are egg-layers. Still, we have no evidence of that yet. -Many modern genera by the Pliocene -All modern species had developed by the Pleistocene |
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Describe the skeletal system's gill arches.
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-main function in the Agnathans is to support the body around the pharyngeal gill slits in the most primitive fishes.
-Modified functions in others: Jaws, jaw support, parts of the skull. -Tiny bones of the human inner ear have also apparently been derived from these gill arches! |
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Describe the skeletal system's vertebral column.
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-Not present in Agnathans.
-Vertebral column present. Little skeletal differentiation amongst the higher fish, virtually identical from front to back. -Modification/regional specialization of vertebrae in amphibians, birds, and mammals (because different vertebrae are serving different purposes!). |
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Describe the skeletal system's ribcage.
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-Major protection and muscle attachment in higher vertebrates
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Describe the skeletal system's sternum.
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-First found in the amphibians
-Highly developed and modified in birds |
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Describe the skeletal system's skull.
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-Cartilaginous in Agnatha, Condrichthyes. Don’t really look like skulls... creepy. Relatively simple, light in weight, and not very protective.
-Bony in the higher fish -Greater fusion in reptiles and other higher forms. The trend is definitely toward fusion and armoring of the bones in the skull. |
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Describe the skeletal system's girdles.
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- the pectoral girdle is attached to the skull in the fishes, and the pelvic girdle is free (both act as fin supports).
-the pectoral girdle is free in tetrapods, and the pelvic girdle is attached to the vertebrae in the rear of the organism. |
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Describe the skeletal system's appendages.
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-Fish fins used for balance and steering, not really support.
-Amhibians and reptiles have laterally held legs for support and a little locomotion. -Birds and mammals have ventral legs for support and locomotion. |
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Describe the muscular system.
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-Fish muscles mostly axial myomeres to power body undulations via contractions.
-Limb muscles small (for fin steering) -Tetrapod limb muscles are massive for both support and non-undulatory locomotion. -Axial muscles are more reduced and specialized (for example, we don’t need the muscles in our trunk for movement much). |
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Describe the integumentary system.
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-From fish on up, there is a general thickening, layering, and moisture-proofing of dead cells at the surface.
-Fish don’t really need moisture-proofing for keeping water in -Also more gland development, hair/fur/feather follicles, etc. More complication goes on in the integumentary surfaces as you travel up the groups. -The major trend is toward protection against drying and abrasion. Higher animals have mechanisms for constantly replacing cells (very obvious in reptiles and birds which shed old skin/molt). |
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Describe the digestive system.
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-Remarkably similar in all vertebrates!
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Describe the respiratory system.
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-Switch from gills to lungs
-Bony fishes have swim bladders homologous to lungs -Generally function in buoyancy, not gas exchange -Trend: after the switch from gills to lungs, there is a gradual increase in lung internal surface area and efficiency from amphibians upward. |
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Describe the circulatory system.
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-Fish have a single-loop circulatory system
-Amphibians and higher groups have a double-loop circulation -One loop is systemic, the other is pulmonary -Fish have a 2-chambered heart -Lungfish have added features to the circulatory system -Amphibians have a 2- or 3-chambered heart -Partial septum separates oxygenated from deoxygenated blood in ventricle -Most reptiles have 3-chambered hearts (with a partial septum as well) -Crocodilians have 4-chambered hearts with a full septum -Birds and mammals have 4-chambered hearts with a full septum as well |
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Describe the excretory/osmoregulatory system.
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-Aquatic vertebrates: gills = the chief organs of excretion/osmoregulation.
-Kidneys first evolved as osmoregulatory organs in fishes to remove water (freshwater) or conserve water (marine). -Freshwater fish pee a lot and it’s very dilute -Marine fish hardly ever pee and it’s very concentrated -Sharks are able to match body concentrations in different environments by retaining or releasing urea -Terrestrial animals: get rid of stuff we don’t need by excretion in feces, urine, respiration, heat, etc. -The losses are equal to the gains! |
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What are the three levels of kidney development?
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-Stages are based upon how much a given vertebrate needs its kidney to do.
-Pronephros: simplest (embryonic fish, early amphibians) -Mesonephros: intermediate (some adult fish and all amphibians, embryonic reptiles, embryonic birds, embryonic mammals) -Metanephros: more complicated (adult reptiles, mammals, and birds) |
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Describe the reproductive system.
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-Little difference between female systems
-Male differences are closely associated with kidney differences (ducts from kidneys for sperm transport, separate ducts develop in some) |
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Describe the nervous/sensory system.
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-Increased complexity of whole system, brain to cope with adaptations of other body systems for life on land.
-Balance, movement, and stimuli are big players in the brain -Most changes in the cerebrum (especially the cortex) -Primarily the olfactory in Agnathans -Some olfaction, integration of complex behaviors in sharks and amphibians -The memory and higher learning regions are in the cortex of reptiles and higher. |
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In energetics, what is the difference between ectothermy and endothermy?
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-Ectotherms: body temperature determined solely by the environment
-Fishes, amphibians, reptiles -Body temperature fluctuates with environment -Can use behavior to keep temperatures within optimal range (if available)—retreating into caves, basking on rocks, etc. -Endotherms: regulate body temperature internally -Birds and mammals (also the dinosaurs, more than likely!) -Most birds: 40-42 degrees C -Mammals: 36-38 degrees C -Balance between heat production and loss -Changes in insulation -Counter-current heat exchange systems, adaptive hypothermia |
