Annelida

Annelids Characteristics –coelomates –Metamerism (= unspecialized segmentation) –In the Classes based on…  Parapodia  Clitellium

Systems IntegumentIntegument- epidermis is one cell layer with mucous gland that secrete a moist cuticle. SkeletalSkeletal -hydrostatic (using coelom) MuscleMuscle- longitudinal and circular muscles Each segments muscles are independent of the other segments. DigestiveDigestive- complete, complex, with typhlosole for absorption and chloragogen cells acting as digestive gland and excretory cells.

Systems, continued ExcretoryExcretory- a pair of nephridia per segment. RespiratoryRespiratory -through skin, some through parapodia; tubeworms have gills. CirculatoryCirculatory- closed system, use hemoglobin as oxygen carrier. NervousNervous- dorsal brain; ventral, double, solid nerve cord, with ganglia in each segment. EndocrineEndocrine- hormones secreted by nervous system. ReproductiveReproductive- –Dioecious in Polychaeta; no special organs, posterior end becomes gonads. –Monoecious in Oligochaeta and Hirudinea; Clitellium.

Annelid taxonomy Phylum Annelida (an-nel-i-da) –Class Polychaeta (poly-key-ta) Nereis, Aphrodita, Chaetopterus, Arenicola, AmphitriteNereisAphroditaChaetopterus, Arenicola, Amphitrite –Class Oligochaeta (ol-e-go-key-ta) Lumbricus, TubifexLumbricus –Class Hirudinea (hi-ru-din-e-a) Hirudo, leechHirudo Earthworm dissection

Nereis (clam worm) Nereis

Aphrodite (sea mouse) ventral dorsal

Other Polychaetes Arenicola (Lug worm) Chaetopterus Amphitrite (plum worm)

Hirudo (leech)

Earthworm cross section