Small sharks with elongated, catlike eyes and large spiracles. The first dorsal fin is over or behind the pelvic fins, there are no precaudal pits, and the caudal fin has no strong ventral lobe. Many shelf species have colorful and variegated patterns of spots, blotches, saddles, stripes, and reticulations, but those found in deeper water often lack them, and range from uniform whitish or pinkish to jet black. Most catshark species are deepwater slope sharks. None is oceanic, and most occur on or near the bottom, though some deepwater slope species range well above the substrate.
None occurs in fresh water.
Catsharks have a vast geographic range in tropical to cold temperate and boreal waters, in all oceans except the Antarctic. Invertebrates, especially crustaceans and cephalopods, small bony fishes and small sharks and rays. Many take bottom prey, but a number of species feed on midwater bony fishes such as lanternfishes and lightfishes. The filetail catshark travels in gender-segregated schools of several thousand. They also have elongated, catlike eyes and comblike rear teeth.