Ctenophores

Ctenophores are also characterized by a pair of tentacles that they spread out like a web to catch zooplankton prey, such as small crustaceans and even small fish. There is even one group of ctenophores, the Beroids, which feeds on other ctenophores, and there are also a few groups that are benthic (they absorb their comb plates following embryonic development and creep along on the ocean floor). Ctenophores have a relatively complicated nervous system consisting of a peripheral nerve net and the apical sensory organ used to sense gravity, and possibly light as well. All ctenophores possess a pair of small anal pores located adjacent to the apical sensory organ thought to control osmotic pressure. They are not quite as ‘simple’ as one might first imagine.