The Phylum Sipuncula
Etymology: From the Greek Acantha a prickle, and Kephale a head.
Characteristics of Sipuncula:
- Bilaterally symmetrical and vermiform.
- Body has more than two cell layers, tissues and organs.
- Body cavity is a true coelom.
- Body possesses a U shaped gut with a mouth and anus.
- Body covered in a rubbery cuticle.
- Has a simple brain and a ventral main nerve.
- Has no circulatory or respiratory organs.
- Reproduction normally sexual and gonochoristic, some species can be asexual and one species is parthenogentic.
- Feed on algae, diatoms, protista etc., one species is a parasite.
- All live in marine environments.