Annelida Segmented Worms

Phylum Annelida Main Characteristics Bilateral symmetry Protostomes Triploblastic Setae Closed Circulatory System Ganglia and Nerve Cords Metanephridia

Phylum Annelida Classes of Annelids Polychaeta – Nereis, Arenicola Oligochaeta – Lumbricus, Tubifex Hirudinea - Hirudo

Phylum Annelida Class Polychaeta Mostly marine Parapodia Cuticle

Phylum Annelida

Polychaeta Feeding Most carnivorous –Some have venom –Gut is straight tube Some are detritovores –Eat dead and decaying matter. Many are filter feeders

Phylum Annelida Christmas Tree Worm

Phylum Annelida Oligochaeta Terrestrial, freshwater, some marine Have a clitellum –For mucus secretion –Used in copulation –Used to form cocoons No parapodia Few setae

Phylum Annelida Oligochaete Locomotion Use circular and longitudinal muscles Can use setae as anchors Use hydrostatic pressure

Phylum Annelida Oligochaete Feeding Scavengers and/or detritovores Path of food –Mouth –Pharynx –Crop –Gizzard –Stomach –Intestine

Phylum Annelida Oligochaete Reproduction Hermaphroditic Must line up clitella Held together by mucus sheath Cocoon formed –Fertilization occurs here –No larval stages Some freshwater species asexual

Phylum Annelida

Hirudinea Terrestrial, freshwater or marine No parapodia Circular, longitudinal and oblique muscle layers

Phylum Annelida Hirudinean Feeding Many carnivorous –Small invertebrates –Body fluids Mouth in the anterior sucker Produce “hirudin” – anticoagulant

Phylum Annelida

Other Hirudinea Systems Gas exchange by diffusion Nervous system –Photoreceptors –Can sense temperature –Sensory papillae pairs of metanephridia for waste

Phylum Annelida Hirudinea Reproduction All sexually reproducing Have a penis for sperm transfer Clitellum seen during breeding season No larval stages