BIO 112 Lecture Notes - Lecture 15: Platypus, Sarcopterygii, Tiktaalik
16 Nov 2016
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Document Summary
All have structure called notochord (running down back during development (fluid filled cells in middle, semi-rigid) Chordates have four defining features : developmental (at least) or some keep until adulthood. Dorsal, hollow nerve cord (develops into brain/spinal chord) Pharyngeal slits or clefts (sometimes used as filter feeding structure) (becomes actual gill in some fish) Vertebrates-having a vertebral column all vertebrates have a tripartite brain & spinal chord. Closed circulatory system with a heart, pumps water over gills digestive system uses muscles to push food through digestive tract. Hagfish-produce slime, have no appendages . some predate others scavenge. /lamprey- disc-like mouth. sucks up stones and then builds a nest with them . parasitic. some are sessile filter feeders. Gnathostomes- jaws and mineralized skeleton has paired appendages. Gill arches are made up of cartilage and support the gills evolved into jaws cartilaginous fish came from an ancestor that lost its bony skeleton.
