The Probert Encyclopaedia of Nature

PHYLUM CHAETOGNATHA

The Phylum chaetognatha are the arrow worms. They are relatively simple triploblastic animals. The body is elongated and transparent. The gut is just a straight tube. The body has three regions; head, trunk and tail. The head bears a hood and rows of chitinous hooks. There is no blood vascular system. Eyes are usually present. The male gonads are in the tail, the female ovaries in the trunk.
Research Phylum Chaetognatha