Scalloped Hammerhead
Appearance: Large, with a broad, narrow-bladed head. Anterior margin of "hammer" is very broadly arched in adults, with a prominent median indentation. Somewhat falcate first dorsal fin with an origin over or behind the insertion of the pectoral fins. Free rear end of second dorsal fin nearly reaches caudal fin. With precaudal pit.
Coloration: Grey-brown (olive), with white ventral surface. Dusky to black pectoral fin tips. Juveniles can have dusky coloration on the tips of the pelvic fins, the lower lobe of caudal fin and the free rear end of the second dorsal fin.
Distribution: Nearly circumglobal in tropical, subtropical and warm-temperate waters. Western Atlantic: New Jersey to Brazil, Gulf of Mexico, Caribbean and Bahamas.
Biology: Probably the most abundant hammerhead species in coastal waters. Can even occur in river mouths and estuaries. Found from the very surface down to about 750 ft. with juveniles living in shallow waters that serve as nursery grounds. Scalloped hammerheads can form seasonal aggregations or live solitary. Both migrating and stationary populations are known.
Feeding: Fishes (e.g. sardines, herrings, anchovies), invertebrates, mainly cephalopods), small sharks (e.g. sharpnose sharks (Rhizoprionodon terraenovae), blacktip reef sharks (Carcharhinus melanopterus) ).
Size: Average size between 8 and 10 ft, maximum total length about 14 ft.
Reproduction: Viviparous, with yolksac-placenta (gives birth to live young). Size at birth between 1.5 and 2 ft. Gestation period lasts between 9 and 10 months. Males reach sexual maturity at about 4.5 to 5 ft., females at approximately 6.5 ft. Pups are born in very shallow water (nursery grounds).
Similar species: Two other species (the Great hammerhead and the Smooth hammerhead) occur in the same area as the scalloped hammerhead but they can be identified by the shape of their "hammer," their first dorsal fin, and their color. .
Population Status: Unknown.
Danger to humans: Potentially dangerous.
