Hemichordates for exam Flashcards
what are they included in?
deuterostome and protochordate
what are the basic features?
deuterostome embryology pharyngeal clefts dorsal hollow nerve cord trimeric coelom torniaria larva bilateral symmetry circulartory system separate sexes
features of enteropneusta?
temperate, sandy, marine, intertidal regeneration - asexual reproduction tripartic - proboscis - burrowing - collar - mouth and nerve tissue - trunk - gill slits and paired coelomic cavity
gill slits in E?
provide an outlet for feeding current that comes in at mouth, help filter out food - U shaped
later theyr’re used in resp whenre the centre of the U stiffens into a gill bar - human communication starts here
how do E feed?
use mucus strands from epithelium collar forming mucoid ropes to mouth, ingest sand/food from mucus
how do E breathe?
across pharynx wall and body epithelium - not gill slits
nerve cord/net in E?
dorsal cord splits in two dorsal and ventral
nerve tracks lack cell bodies - theres an occasional exception to this
system conducts rather than coordinates
E larva?
tornaria - indistinguishable from some echinoderms - close relationship
adults foreshadow chordates, larva don’t
features of pterobranchs?
tiny and colonial - basal lineage
tripartic - single gill slit
collar bears ciliated tentacles - lophophore
what are lophophorates?
have some deuterostome features
have - 3 part coelomate body, chitinous exoskeleton, U-shaped gut and lophophore
what is the lophophore?
tentaculate feeding organ w/ ciliated tentacles
surrounds mouth
feeding current down middle and out sideways
frontal cilia trap food
features of phorondia?
marine, benthic worm-like filter feeder u-shaped gut mouth w/in lophophore anus outside horseshoe shaped lophophore - filter feeds, respires and excretes
features of brachiopoda?
lamp shells, shallow seas, fossils
two calcerous shells - offset - dorsal and ventral
stalked
internal space taken up by lophophore supported by thin chiton skeleton
features of bryozoa?
colonies of sheets/trees of tiny animals individual zooids marine/freshwater lophophore pokes out of chitinous box three part body reduced anatomy no circulatory system minimal nervous system U -shaped gut lophophore
whats special about bryozoa?
show polymorphism - mostly feeding zooids but also defensive, cleaning and sexual
phenotypic plasticity - vary with environment - colonies at shores have more spines than sheltered colonies
