BIO 2135 Chapter Notes - Chapter DigiDiv: Dissolved Organic Carbon, Clitellata, Pericardium
24 Feb 2017
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The head (composed of the prostomium and peristomium) and the pygidium (most the division of the body into a series of identical units posterior part, with anal opening) are not true segments. Bundles of setal hairs, formed from beta-chitin. Gas exchange occurs across the body wall. Contractile dorsal vessel pushes blood forward, a ventral one moves it back. Capillary beds connect two major blood vessels. Anterior brain lies on top of pharynx. On each metamere, there is a pair of bilobed parapodia with bundles of setae. Parapodia: paired lateral, unjointed appendages roles in locomotion and respiration. Absence of permanent gonads; only form on septa between segments in breeding season. Ciliated larva trochophore with three body parts prototroch, metatroch, telotroch. Segments are added between the metatroch and telotroch. Errant forms swim or crawl across a substrate predatory. Sedentary forms live in burrows filter feeders, particle collecting, can have elaborate tentacles (these and parapodia increase surface area)
