BIO 2135 Study Guide - Final Guide: Marine Worm, Annelid, Peristomium
Document Summary
Closed circulatory system: the development of the closed circulatory system in combination with metamerism was important in ensuring that nutrients were evenly distributed throughout the ancestral annelid, the hydraulic medium is now the principle role of the coelom. Class polychaeta: each segment contains a pair of bilobed parapodia with bundles of setae. Parapodia increase the body surface available for gas exchange and are highly vascularized. Upper lobe of parapodia is called notopodium and the lower one is called. The parapodia are moved by means of oblique muscles: the gonads only form on the septa between the segments during the breeding season. Polychaetes are dioecious (organisms that have the male or female reproductive structures in separate individuals. ); male and female gametes are released directly into the coelom and pass to the outside through either coelomoducts or by rupturing the segment: trochophore larva with three body parts: a prototroch, a metatroch, and a telotroch.
