BIO 2135 Study Guide - Final Guide: Hydrostatic Skeleton, Ventral Nerve Cord, Nephridium
20 Apr 2017
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Annelida (autapomorphies: metamerism of mesodermal structures, metamerism: repeat of mesodermal structures to accommodate a larger organism. Four bundles of setae formed from beta-chitin: setal hairs made from chitin are used to push against the substrate, contributes to unique form of locomotion, gives them a grip to push across substrate floor. Tentacle diversity: christmas tree, tufts of hair, leeches reduced to parasitic existence in marine envt, originally peristomium that transformed into tentacle, leeches are ancestral annelid that reduced itself to parasitic living, 1% of biodome existence of animalia (0. 9%) Ingest the medium by which they"re moving - first burrowers to do this. If they need to moisten their skin, they sacrifice the coelomic fluid and increase the flow out of the nephridiopore. Skin is their respiratory surface, will suffocate if dry: melting snow has little or no oxygen dissolved in it, so it fixates the earthworm, they come outside and airate their skin.
