BISC 121Lg Lecture Notes - Lecture 15: Trematoda, Lophophore, Cestoda
Document Summary
Monogeans and trematodes live as parasites in and on animals: wide ranges of host, sexual and asexual life cycles, trematodes that parasitize humans typically live in snails. Transferred to humans in water: (cid:272)histoso(cid:373)iasis (cid:272)a(cid:374) (cid:271)e (cid:271)e(cid:374)ig(cid:374) as s(cid:449)i(cid:373)(cid:373)er"s it(cid:272)h or (cid:272)hro(cid:374)i(cid:272) ~30,000 species of fossils from paleozoic and mesozoic eras. Were displaced from valve molluscs, therefore they never recovered from mass extinction: molluscs- ciliated trochophore larvae. Octopus, squids, snails, slugs, oysters, and clams. Soft bodied but may have a caco3 shell. Polyplacophora- chitons, marine, 8 plate shells, foot for locomotion, no head. Very complex: most bivalves have gills for feeding and gas exchange. Suspension feeders: polyplacophora use a muscular foot to grip rocky substrates tightly. Grazers eat algae: gastropods are usually marine. Undergo torsion- visceral mass rotated 180 degrees so the anu and mantle are above the head: bivalves- right and left valves. Powerful adductor muscles keep the shell closed.
