Cephaloscyllium is a genus of catsharks, and part of the family Scyliorhinidae, commonly known as swellsharks because of their ability to inflate their bodies with water or air as a defense against predators.

The genus Cephaloscyllium was proposed by American ichthyologist Theodore Gill from the Greek kephale ("head") and skylion ("dogfish"), in an 1862 issue of Annals of the Lyceum of Natural History of New York.

Cephaloscyllium did not gain wide acceptance until Samuel Garman published "The Plagiostomia" in a 1913 volume of Memoirs of the Museum of Comparative Zoology, in which he recognized three species: C. isabellum, C. ventriosum, and C.

[3][4][5] There are currently 17 recognized species in this genus: Morphological and molecular phylogenetic studies have shown the closest relative of Cephaloscyllium to be Scyliorhinus, and these two genera and Poroderma form the subfamily Scyliorhininae, the most basal clade of the order Carcharhiniformes.

The most far-flung members of the genus are C. sufflans off southeastern Africa, C. silasi off southwestern India, C. umbratile in the northwestern Pacific, and C. ventriosum along the western coast of the Americas.

[4] One hypothesis states Cephaloscyllium originally evolved in Australia and New Guinea, and subsequently dispersed outwards in a series of colonization events, eventually reaching Africa and the Americas.

[4] Cephaloscyllium species, bottom-dwelling sharks, can be found from the intertidal zone to a depth of 670 m (2,200 ft) on upper continental and insular slopes.

[4] Of the species whose diets have been documented, they have been known to feed on a wide variety of benthic organisms, including other sharks and rays, bony fishes, crustaceans, and molluscs.

[4] Several species (e.g. C. umbratile and C. ventriosum), are known to be extremely hardy, capable of surviving out of water for extended periods and adapting readily to captivity.