BIOL 1911 Lecture Notes - Lecture 33: Gastrointestinal Tract, Hirudin, Filter Feeder
24 Mar 2018
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33. 3 lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms. Chitons: clade polyplacophora, oval-shaped body and a shell composed of eight dorsal plates, foot acts as suction cup to stick to rock and is also used in movement, use radula to scrape algae off rock. Annelids: little rings = body resembles a series of fused rings, segmented worms, coelomates, <1mm to >3 mm, phylogeny recently revised into two clades. Inhabit sea, freshwater, damp soil: grouping reflects broad differences in lifestyle. Errantians: large and diverse group, most are marine, most are mobile, some swim, other crawl, predators, grazers of algae, some relatively immobile species. In many, there are parapodia that function in locomotion: prominent paddle-like or ridge-like structures, each has numerous chaetae, richly supplied with blood vessels, many also function as gills, well-developed jaws and sensory organs.
