An order of sharks comprising six families, 24 genera, and 97 species, commonly known as dogfish sharks. The order differs from all other sharks by the following combination of characters: two dorsal fins, with or without spines; no anal fin; spiracle behind eye; and lower nictitating eye membrane absent. For the most part, squaliform sharks inhabit continental and insular shelves and slopes, and sea mounts. Some species live at great depths. So far as known, squaliforms are ovoviviparous and produce from one to 22 pups per litter, depending on the species. The dwarf lantern shark (Etmopterus perryi), at 17 cm (6.7 in.) in length, probably is the world's smallest shark; the largest squaliform is the Pacific sleeper shark (Somniosus pacificus), which is up to 7 m (23 ft) in length. The diet consists of bony fishes, cephalopods, crustaceans and other invertebrates, mammals, and other sharks.