Phylum Annelida Segmented Worms Leech Christmas tree worm Fireworm Feather duster worm

Annelid Characteristics Segmentation = Metamerism metameres (=somites, segments) Show true segmentation - both internal and external Allows for specialization

Annelid Systems All systems found in Annelids but skeletal Complete digestive tract - some specialization - crop and gizzard Closed circulatory system - is segmentally arranged dorsal and ventral vessels aortic arches (hearts)

Annelid Systems All systems found in Annelids but skeletal Excretion Nephridia - segmentally arranged

Annelid Systems All systems found in Annelids but skeletal Nervous system ladder shaped pair of cerebral ganglia double ventral nerve cords pair of ganglia in each segment several sensory structures taste buds tactile organs eyes in some statocyst

Annelid Systems Reproduction some are monoecious, others dioecious marine species have trochophore larvae some have asexual reproduction by Budding fragmentation

Annelid Systems Respiration across body surfaces some have gills some use parapodia

Class Polychaeta Make up 2/3 of phylum most primitive annelids; ancestral to other two classes almost all are marine, few freshwater species

Polychaet Characteristics differentiated head Tentacles first segment Prostomium Peristomium Mouth Palps eyes

Polychaet Characteristics Parapodia- lateral appendages notopodium- dorsal neuropodium- ventral acicula- rods Respiration By parapodia

Polychaet Characteristics Reproduction sexes separate no permanent gonads egg and sperm form from coelomic peritoneum pass out of nephridia or burst thru body wall fertilization is external in sea free swimming larva- trochophore

Polychaet Ecological Types free living- all are predators tube dwelling- all are filter feeders secrete their own tube burrow into substrate

Class - Oligochaeta Terrestrial or Freshwater No distinct head - but contains pro- and peri- stomium Clitellum - present at all times Used in copulation Cocoon production

Class - Oligochaeta Reproduction Monoecious Copulation Internal fertilization Eggs laid in cocoon no larval stage

Class - Oligochaeta Digestive system - well differentiated mouth pharynx crop gizzard intestine - Typhlosole Anus

Class - Oligochaeta Circulatory system Respiration Excretion Closed 5 pairs of aortic arches Hemoglobin Respiration Body surface Excretion Nephridia

Class - Hirudinea Freshwater or terrestrial Have suckers Segmentation fixed (34 segments) Clitellum only during season Digestive tract large crop Anticoagulant Medically important