The swellshark, Cephaloscyllium ventriosum, is a catshark of the family Scyliorhinidae. It is found in the subtropical eastern Pacific Ocean between latitudes 40° N and 37° S, from the surface to 460 m.It grows to about 100 centimeters (39 in) in length, and can expand its body to about double its regular size to prevent its predators such as seals and larger sharks from pulling it out from rocky reefs, under ledges, and in crevices.