BIOL 2030 Study Guide - Final Guide: Agnatha, Eustachian Tube, Thyroid
Document Summary
Chapter 15 phylum chordata: name comes from notochord (rod like tissue enclosed in a sheath) Primitive characteristics: chordates share features with some invertebrates: bilateral, anteroposterior axis, coelom, tube-within-a-tube body plan, metamerism, cephalization. Chordata cladogram: two subphyla: protochordata (tunicates and lancelets) and vertebrata, two superclass/taxon of vertebrata: agnatha (no jaw) and gnathostomata (with jaw, clade amniota develop their young in amnions. In most invertebrate phyla solid and ventral to digestive tract. In higher chordates secretes iodinated proteins: post anal tail posterior to anus, provides motility; increased efficiency in fishes; but vestigial (human coccyx) Subphylum urochordata (tunicata: found in all seas; most are sessile but larvae are motile, divided into 3 classes ascidiacea (most understood); appendicularia; thaliacea. Tunicate body plan: tough, non-living test that surrounds them and contains cellulose, during adult metamorphosis, notochord and tail disappear, dorsal hollow nerve cord is reduced to a single ganglion.
