|The family Tethyidae
includes laterally compressed dendronotids with large, elaborate
cerata and a large oral hood lined with tentacles that they use
to capture the small crustaceans and other invertebrates on which they
feed. Most can swim by
lateral flexing if disturbed and can autotomize their cerata. Some
retain zooxanthellae in their tissues. At least four species are known
from Hawaii in one genus (Melibe).