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20 Cards in this Set
- Front
- Back
Phylum Hemichordata
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Arrow worms; not off of Chordata. they are sediment or filter feeders that burrow or make shelters and use probiscis to gather food
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Phylum Chordata
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have 5 characteristics. 1) notochord 2. pharyngeal slits 3. endostyle 4. dorsal nerve cord 5. muscular, postanal tail. no vertebrate column or brain. all 5 seen in development
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Notochord
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formed by turgid cells inside fibrous sheath. segmented muscles bend it with a pulling motion instead of body shortening which produces undulatory motion for swimming
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Pharyngeal slits
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originally used in filter feeding, but later adapted for gas exchange(gill slits)
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Endostyle
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primitive version was used to secret mucus to trap particles. vertebrates use the thyroid gland(endostyle) for energy and thermoregulation
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Dorsal, hollow nerve cord
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most protosomes have a ventral, solid, paired nerve cord(arthropods)
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Postanal tail
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used for locomotion in aquatic environments. used as defense and balance in terrestrial. used for defense and grasping in arboreal(tree)
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Subphylum Urochordata (tunicates, sea squirts)
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notochord does not extend to head! suspension feeders(mistaken for sponges). free swimming larvae and becomes sessile as adult. nervous system and notochord degenerate and tunic* surrounds body.
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Subphylum Cephalochordata (lancelets)
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notochord does extend to the head! suspension feeders that can swim well and usually lie half buried in the sand. closed CS pumps thru PhyS, segmented trunk muscles, small amount of cephalization.
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Subphylum Vertebrata (craniates)
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possess endoskeleton. no molt, but have loss of protection. well developed head, eyes and brain. Key developments: neural crest and ectodermal placodes, cranium & forbrain, senses, CSm myelin sheath
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Superclass agnatha
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no jaws
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superclass myxini (hagfish)
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only craniates w/out vertebrate. scavengers
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superclass petromyzontida (lampreys)
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only vertebrates w/out jaws. parasitize fish
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gnathostomata
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all vertebrates except lamprey. they have paired limbs for maneuverability, muscular jaws(gill arches). started arms race
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Chondrichthyes(carilagenous fish; sharks, rays)
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bony from mineralized cartilage, replaced w/only a lining of calcified hard tissue(lighter) large livers filled w/oil, and skin covered w/ placoid scales
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osteichthyes(bony fish)
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freshwater origin w/ no electrosensative organ. primitive lungs that helped in drying out or low oxygen(became swim bladder). two clades: actinopterygii and sarcopterygii
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actinopterygii(ray finned)
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most abundant, extra hox genes, mostly freshwater, most suck in prey
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sarcopterygii(lobe finned)
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fins w/ sturdy bones at base*, 1st tetrapods(stocky predators), but still mostly aquatic(tail fin, eyes on top). needed movable neck, sturdier limbs, and connection of limbs to axial skeleton to move to land
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amphibians
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mucus gland in skin help reduce water loss, needed lungs to breathe b/c of mucus, metamorphosis common
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amniotes
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amniotic egg*, has internal fertilization, skin resistant to water loss, lipids for waterproofing, keratinized scales, ribs & better lungs, longer limbs, strong ankle, large feet
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