|The family Phylliroidae
contains highly specialized, planktonic species--the only
known to live a holoplanktonic existence. Their
bodies are highly flattened and lack cerata while the foot is greatly
reduced. They swim by lateral undulation and feed on hydromedusae and
larvaceans. Some species are bioluminescent. Two
species are known from Hawaii in the genera Cephalopyge and Phylliroe.