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Annelida

Annelida

Overview

Phylum annelida can be broken into three main groups: Oligochaetes (earthworms), Hirudinians (leeches), and Polychaetes (bristle worms). Primary characteristics of annelids include bilateral symmetry, a complete digestive tract with organ systems, body segmentation, and hydrostatic skeleton. Annelids inhabit a wide range of environments including both terrestrial and marine. They have a variety of feeding modes including being detritivores, deposit feeders, filter feeders, herbivores, predators, and some are even parasitic.

Classes of Annelida present in the Cretaceous of the Western Interior Seaway