Zoo-Lab (Sem-1) - Exercise 14: Phylum Annelida

Phylum Annelida

true segmented worms; triploblastic with bilateral symmetry; examples include earthworms, sandworms, and leeches

Oligochaeta; Polychaeta; Hirudinea

representative classes of Phylum Annelida

Class Oligochaeta

lives in freshwater or moist soil; locomotory organs are setae; head indistinct; and hermaphroditic

Pheretima maharabensis

earthworm; body is divided into segments or metameres; first incomplete segment: prostomium; first complete segment: peristomium; bristles: setae; 14th, 15th, 16th swollen segment: clitellum; anus at the third end; vagina at 14th segment; male genital openings at 18th

Class Polychaeta

sandworms and tubeworms; mostly marine; with lateral parapodia bearing setae; head bears tentacles; separate sexes; free-living

parapodium

locomotory organ of polychaetes

Nereis sp.

sandworm/ragworm

Class Hirudinea

leeches; dorso-ventrally flattened; completely segmented internally and marked externally with rings/annuli to each segment; large sucker is found at the postero-ventral end of the body; small oral sucker surrounding the mouth; anus located just above the posterior sucker on the mid-dorsal line; no parapodia or setae

Hirudo medicinalis

medicinal leeches