Annelida Characteristics

Symmetry
Annelids have a bilateral symmetry. Some have line segments to show each body part, and also have a bandage called the clitellum which is close to the worm's head. The worm's head doesn't have eyes, nose, or ears, but a mouth structured for its specific environment. Earthworms have a simple mouth to chew up dirt, roots, and leaves. Giant tube worms have a plume (feather) to filer out molecules essential for survival. Leeches have a huge sucker filled with razor-shaped fangs.

Reproduction
The reproduction of worms is asexual and sexual. Fertilized eggs of marine annelids usually develop into free-swimming larvae. In addition, eggs of terrestrial forms are enclosed in cocoons and hatch as miniature versions of the adults. The ability to regenerate lost body parts is highly preferred in many polychaetes and digochaetes, which is an asexual reproduction.

Organs
They have loads of body parts that are duplicated in each segment. The digestive system of annelids consists of an unsegmented gut that runs through the middle of the body from the mouth, located on the underside of the head, to the anus, which is on the pygidium. The circulatory system is usually closed, confined within well-developed blood vessels; in some polychaetes and leeches the circulatory system is partly open, with blood and coelomic fluid mixing directly in the sinuses of the body cavity.The nervous system typically consists of a primitive brain, or ganglionic mass, located in the head region, connected by a ring of nerves to a ventral nerve cord that runs the length of the body; the cord gives rise to lateral nerves and ganglia in each segment.