EVERYDAY SCIENCE

Detailed explanation-1: -The pygidium is the posterior, or back, end of the worm and houses the anus. Annelids grow by adding segments to the region just in front of, or anterior to, the pygidium. Segmented worms are also capable of regrowing regions of the worm that are broken off.

Detailed explanation-2: -In front of the pygidium is the posterior growth zone (pgz), where new segments are made. B) Generalized structure of the nervous system in naidids.

Detailed explanation-3: -The segmental organs are either protonephridia or metanephridia and basically function as excretory organs. During maturity, they are modified to be able to release gametes from the coelom. Thus, gonoducts are identical with nephridia in most polychaetous annelids.

Detailed explanation-4: -Segmented Bodies Metameric bodies are divided into segments called annuli. The annuli are covered in tiny hairs called setae. Setae help the worms move. Each segment contains parts of the organism’s excretory, circulatory, reproductive, and nervous system!

Detailed explanation-5: -annelid, phylum name Annelida, also called segmented worm, any member of a phylum of invertebrate animals that are characterized by the possession of a body cavity (or coelom), movable bristles (or setae), and a body divided into segments by transverse rings, or annulations, from which they take their name.