Oceanic whitetip

The oceanic whitetip shark (Carcharhinus longimanus) is a large, stocky requiem shark that lives in the open ocean across tropical and warm temperate seas. Its most recognizable features are its long, rounded fins, each tipped in white. While generally a solitary hunter, it will congregate in large groups where food is abundant. The IUCN Red List classifies this species as critically endangered, as heavy fishing for its fins and meat has driven steep population declines.

This shark is also known by several common names, including the brown shark, shipwreck shark, whitetip shark, and lesser white shark. It was first scientifically described in 1831 by naturalist René-Primevère Lesson, who named it *Carcharhinus maou*. Zoologist Felipe Poey later described it in 1861 as *Squalus longimanus*, and the name *Pterolamiops longimanus* has also been used. Although the rules of taxonomic priority favor Lesson’s original name, *Carcharhinus maou*, the name *Carcharhinus longimanus* remains widely accepted because Lesson’s name was forgotten for so long. The species epithet *longimanus* comes from Latin, meaning “long hands,” a reference to the size of its pectoral fins. Fossil teeth of this species have been found from the Early Miocene of Odisha, India, as well as from the Pliocene of Italy and Spain.

The oceanic whitetip is found worldwide between 45°N and 43°S latitude. It inhabits deep, open oceans where the water temperature exceeds 18 °C (64 °F), preferring temperatures above 20 °C (68 °F) and up to 28 °C (82 °F). It can tolerate waters as cool as 15 °C (59 °F) but avoids anything colder. Once extremely common across a wide band of the globe, its numbers have drastically declined in recent years. The shark spends most of its time in the upper 150 meters (490 feet) of the ocean, favoring offshore, deep-water areas. Longline capture data show that populations increase with distance from land, though the shark is occasionally found close to shore in waters as shallow as 37 meters (120 feet), especially around oceanic islands and narrow continental shelves.

The most distinctive features of *C. longimanus* are its long, wing-like pectoral and dorsal fins, which are significantly larger than those of most other sharks and have conspicuously rounded tips. Its snout is rounded, and its eyes are circular with nictitating membranes. The body is countershaded—grey-bronze on top and white underneath. As the name suggests, most fins (dorsal, pectoral, pelvic, and caudal) have white tips, which may also be mottled; young sharks can have black marks. A saddle-shaped patch sometimes appears between the first and second dorsal fins. The shark has two tooth morphs: those in the lower jaw are thinner with serrated tips, while those in the upper jaw are triangular, much larger, wider, and fully serrated. The lower jaw holds 13 to 15 teeth on each half, and the upper jaw holds 14 or 15. The dermal denticles are nearly flat and wide, typically with five to seven ridges, and they overlap little, leaving some bare skin. This is a robust, large-bodied shark. The largest specimen ever caught measured over 4 meters (13 feet) in length, though most grow to about 3 meters (10 feet) and weigh 150 kilograms (330 pounds). The International Game Fish Association lists an all-tackle record of 167 kilograms (368 pounds) for a 2.2-meter (7.2-foot) individual, suggesting that larger sharks weigh much more. Females are typically about 10 centimeters (3.9 inches) larger than males. In the Gulf of Mexico during the 1950s, the average weight was 86.4 kilograms (190 pounds), but by the 1990s, the average had dropped to 56.1 kilograms (124 pounds).

The oceanic whitetip is usually solitary, though it gathers where food is plentiful. It swims both day and night, generally moving slowly while cruising near the surface in open water. During summer, when the ocean surface is warmer, it tends to swim faster and at greater depths. It has been observed breaching out of the water, similar to a whale. Its diet consists mainly of pelagic cephalopods, such as squid, and bony fish like lancetfish, threadfins, oarfish, barracuda, jacks, mahi-mahi, marlin, tuna, and mackerel. However, it is an opportunistic feeder and will also eat stingrays, sea turtles, seabirds, gastropods, crustaceans, and marine mammal carcasses. It feeds by swimming through schools of frenzied tuna with its mouth open, waiting for fish to swim in before biting down. When whaling was common in warm waters, oceanic whitetips were the most frequent scavengers of floating carcasses, which may explain why they are sometimes called “whaler sharks.” They often compete for food with silky sharks, which may account for their leisurely swimming style combined with aggressive displays. They are known to follow pilot whales, as both species feed on squid. Sucker scars on the skin of an individual filmed off Hawaii suggest that this shark may also dive deep enough to battle large squid.