Lecture 12 Flashcards
five anatomical features that are unique to chordates
ciliated pharyngeal gill slits
dorsal nerve cord (can sometimes be hollow
notochord (supportive lateral, flexible structure that is now really on present in early embryos)
postanal tail
endostyle (thickening of the ventral pharynx)
general body structure of hemichordates
deuterostomes
body in three parts: proboscis, collar and trunk
tripartite coelom
open circulatory system
ciliated pharyngeal gill slits
dorsal nerve cord
shared features of echinoderms and hemichordates
both belong to the deuterostome clade, specifically the ambulacraria clade
bilateral larvae
mesodermal coelom
both lack a highly centralized nervous system
limited cephalization
hemichordate nervous system
dorsal nerve cord, connected to various sensory structures allowing for coordination’s and response to environmental stimuli
why is the development of jaws and paired fins considered to be a major evolutionary development
derived from gill arches
describe counter current exchange
permits highly efficient transfer of solutes across membranes
water flows to the right
blood flows to the left
change in concentration gradient allows for optimal diffusion
salt water fishes lose water due to the masive change in salt conc between their bosy and ocean
water wants to flow into fresh water fish and salt wants out
phylum chordata
thre principle groups:
- cephalochordata
- urochordata
- craniata
stenohyline
capable of living in a limited range of salt conc
euryhaline
capable of living in a wide range of salt habitats
