Phylum Ctenophora

Phylum Ctenophora includes animals such as Pleurobrachia and Ctenoplana, commonly called comb jellies or sea walnuts. They are exclusively marine, free-swimming animals.

Like Cnidaria, ctenophores are diploblastic and radially symmetrical, and follow the blind sac body plan, but they have reached a true tissue level of organisation. Locomotion is carried out using eight longitudinal rows of ciliated plates called comb plates, which beat in coordinated waves. A characteristic feature of the group is bioluminescence — the ability to produce their own light.

As in cnidarians, digestion in ctenophores is both extracellular (within the gastrovascular cavity) and intracellular (within cells). Reproduction is sexual, with indirect development through a larval stage. …