Annelid worms have what’s known as a hydrostatic skeleton, or hydroskeleton. … The body shape of the Phylum Annelida is therefore supported by this strange, liquid-based ‘skeleton’, which is not at all like our own skeleton. We humans do, however, have a coelom – though ours is full of our organs and organ cavities.

Are annelids vertebrates?

A major invertebrate phylum of the animal kingdom, the annelids number more than 9,000 species distributed among three classes: the marine worms (Polychaeta), which are divided into free-moving and sedentary, or tube-dwelling, forms; the earthworms (Oligochaeta); and the leeches (Hirudinea). …

What is the characteristics of annelids?

Characteristics of Phylum Annelida They have a long and segmented body. Annelids are bilaterally symmetrical. They are triploblastic. Also, they exhibit organ system grade of organisation, showing organ differentiation.