The genera and species of "Nurse sharks"

This family consists of 3 species, separated in 3 genera. All have small transverse mouths in front of their eyes and short to long barbels. The position of the spiracles is behind the eyes and not below. Both dorsal fins are either of equal size or the first one can be slightly bigger. The origin of the first dorsal fin is slightly anterior or over the bases of the pelvic fins. The second dorsal fin is in front of the origin of the anal fin. Nurse sharks are very common in tropical and subtropical waters world-wide over the continental and insular shelves, from intertidal regions down to about 70 m . Nurse sharks prefer rocky or sandy bottom, or coral reefs, or even mangrove areas. They can often be found in aggregations while resting on the bottom. They feed on bony fishes, crabs, molluscs, corals and even sea urchins. Nurse sharks possess either an ovoviviparous (aplacental viviparous) or oviparous (egg laying) style of reproduction.