Phylum Annelid - the segmented worms

Class Polychaeta -

Class Oligochaeta -

Class Hirundinea -

Coelomates

Metamerism

Most have Setae

Body Plan = Prostomium & Pygidium

hydrostatic skeleton

Closed Circulatory system

Excretory system - nephridia

Class Oligochaeta

setae - on each segment.

Digestion - Mouth, muscular pharynx, crop, gizzard, intestine (folded typhlosole)

Chloragogen tissue

Circulatory System is closed

Dorsal vessel -->> aortic arches -->> ventral vessel.

Gas exchange - across moist skin.

Excretion - metanephridia

nephrostome, nephric tubules, bladder, nephridiopore.

Nervous System - cerebral ganglia, connectives, ventral nerve cord.

Reproduction and Development

monoecious.

Male structures: testes, seminal vesicles.

Female structures: Ovaries, oviduct

Seminal receptacles receive sperm from mate.

clitellum. It secretes mucous to help hold the mating pair together.

Class Polychaeta

largest class. Many setae on parapodia

no clitellum

Many build own tubes = tubicolous or freeliving.

Parapodia - locomotion and respiration.

In contrast to the other annelids, they usually have separate sexes.

Class Hirundinea

Usually flattened dorsoventrally.

Sawlike chitinous jaws used to cut through the skin.

Like Oligochaetes - monoecious and have a clitellum.

Unlike other annelids, their coelomic cavity is not divided up into compartments and do not have septa.