The spinner shark (Carcharhinus brevipinna) is a type of requiem shark known for its remarkable aerial displays, earning its name from the distinctive spinning leaps it performs out of the water. Found in tropical and warm temperate waters across the globe, this fast and active predator often forms schools.
Identifying Spinner Sharks
Spinner sharks possess a slender, streamlined body, typically presenting with a gray or bronze coloration on their upper side and a white underside. They are characterized by a long, narrow, and pointed snout. While young individuals have unmarked fins, adults develop distinct black tips on their second dorsal fin, pectoral fins, anal fin, and the lower lobe of their caudal fin.
Spinner sharks can be mistaken for blacktip sharks due to their similar appearance. However, the spinner shark’s first dorsal fin is positioned further back on its body, and adults have a distinct black tip on their anal fin. An average adult measures around 2 meters (6.6 feet) and weighs about 56 kilograms (123 pounds), though some can reach 3 meters (9.8 feet) and 90 kilograms (200 pounds). Their teeth are narrow and triangular, designed for grasping small prey.
Hunting and Habitat
Spinner sharks inhabit subtropical, tropical, and temperate regions, from coastal to offshore waters over continental and insular shelves. They are found at depths between 0 and 100 meters (0-328 feet), preferring shallower waters less than 30 meters deep. These sharks are highly migratory, often moving into inshore areas during spring and summer for reproduction and feeding. Their distribution includes the Western Atlantic, Eastern Atlantic, and Indo-West Pacific.
Spinner sharks primarily eat small pelagic bony fish like sardines, herring, anchovies, mullet, tuna, and bonito. They also consume cephalopods such as squid and octopi, and occasionally stingrays. The species is known for its unique hunting method: it swims rapidly through fish schools, spinning along its longitudinal axis while snapping at prey. This momentum often carries the shark out of the water, where it continues to spin, sometimes reaching heights of up to 20 feet, disorienting the fish below.
Spinner Sharks and Humans
Spinner sharks are not considered a significant threat to humans. Their teeth are adapted for catching small fish, not for tearing flesh from large prey. Interactions can occur, particularly if sharks are attracted to spearfishing activities or become excited during a feeding frenzy. The International Shark Attack File has recorded 16 unprovoked attacks attributed to spinner sharks, none of which have been fatal.
The spinner shark’s conservation status is listed as “Vulnerable” by the IUCN Red List. This vulnerability stems from threats like commercial fishing, where they are caught for meat, fins, liver oil, and skin. Misidentification as blacktip sharks in fisheries can lead to underreporting of their catch. Habitat degradation, especially in their inshore nursery areas, also poses a challenge to their populations.