The genera and species of "Houndsharks"

Houndsharks are small to moderately sized with horizontally oval eyes, nicitating eyelids and small spiracles. Although their general appearance resembles requiem sharks, they do not have a precaudal pit. The first dorsal fin is closer to the pectoral fins than to the pelvic fins. The family of houndsharks is one of the larger shark families with 9 genera and 34 species, most of which are found in tropical and temperate coastal areas over the continental shelves. Some of the species have a depth range down to 2000 m but none of them is oceanic. Most prefer sandy, muddy or rocky bottoms. They have been seen around river mouths but no species of this family is able to tolerate freshwater for a long periods of time. Some of them swim in schools. Two styles of reproduction can be found in this family: placental and aplacental viviparity (ovoviviparity).