Spinner Shark

Spinner SharkThe spinner shark (Carcharhinus brevipinna) is large and slender shark with a long and pointed snout. Small eyes. First dorsal fin is small and semifalcate. Origin of first dorsal fin usually over or slightly posterior to pectoral free rear tip. No interdorsal ridge. It is grey-bronze coloration, white belly. Most often with a narrow, white band on flanks, sometimes not conspicuous. Large juveniles and adults with black tips on pectoral fins, second dorsal fin, anal and ventral caudal lobe, and sometimes on pelvic fin, first dorsal and fin and dorsal caudal lobe, too.

The spinner shark is found in the western Atlantic from North Carolina (U.S.) to the northern Gulf of Mexico and the Bahamas. This shark has also been reported in waters around Cuba. It also resides from southern Brazil to northern Argentina. In the eastern Atlantic Ocean, it is found from Spain to Namibia, including the southern Mediterranean Sea. In the Indo-West Pacific, the spinner shark is found in the Red Sea, south to South Africa, eastward to Indonesia, northward to Japan, and then south to Australian waters.

Distributed from inshore to offshore waters over continental and insular shelves, the spinner shark lives in subtropical regions primarily between 40°N and 40°S. Depth of habitat ranges from 0-328 feet (0-100 m). The spinner shark forms schools and is considered a highly migratory species off the Florida and Louisiana coasts and in the Gulf of Mexico, moving inshore during spring and summer months to reproduce and feed.

Although juvenile spinner sharks move into lower portions of bays with the tides, they avoid areas of low salinity.

The spinner shark is an active, fast swimming shark that is often seen leaping out of the water, spinning (from where it gets its common name), in pursuit of prey.

The spinner shark feeds primarily on pelagic fishes including ten-pounders, sardines, herrings, anchovies, sea catfish, lizardfish, mullet, bluefish, tunas, bonito, croakers, jacks, mojarras, grunts, tongue-soles, stingrays, cuttlefish, squid, and octopi. It has an unusual method of feeding, swimming rapidly through schools, spinning along the axis of its body. The shark snaps in all directions at the quickly scattering fish, followed by leaping out of the water. This feeding behavior has also been reported for the blacktip shark (C. limbatus), although to a lesser degree. During feeding and scavenging events, spinner sharks sometimes form aggregations. These sharks have been also reported to scavenge discarded fish from fishing vessels.

Spinner sharks are "viviparous", or livebearing, with embryos nourished by a yolksac-placenta. The gestation period lasts 12-15 months with birth occurring at inshore locations during the summer months for stocks located off North America. Stocks located in the Mediterranean move inshore to give birth during summer off the North African coast. Litter size is from 3-15 pups, each measuring between 24-30 inches(60-75 cm) in length. The pups immediately move into shallow estuarine waters for protection from predators and readily available food sources.