Tiger shark

• 1. Introduction

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  The tiger shark, Galeocerdo cuvier, has been found with automobile license plates, oil cans, tires and baseballs in its stomach. People call it the garbage can of the sea. The nickname is a joke, but it points to a real puzzle about how this predator lives. It hunts mostly at night, and it hunts alone. This documentary follows a handful of questions. What does a shark eat when it will eat nearly anything? How does it find a meal in the dark? Where do its young come from, and why do people both fear it and hunt it? The first answer lies in what else turns up in those stomachs.

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• 2. The Widest Menu

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  A tiger shark of about 2.3 m is reaching a turning point in its diet. Below that length, the young hunt small fish, rays, small jellyfish, crustaceans and mollusks, including cephalopods. They also take smaller sharks, among them reef sharks and even small tiger sharks. Near sexual maturity, the menu widens sharply, and much larger animals become regular prey.

  Adults eat a broader range of food than any other shark. Crustaceans, seals, sea lions, birds, squid, octopus, sea snakes, rays and dolphins all appear on the list. The dolphins include bottlenose, common and spotted species. Adult sandbar sharks are taken too, and so are other tiger sharks. Sea turtles matter most, including the three largest species: the leatherback, the loggerhead and the green turtle. Adult sea turtles were found in up to 20.8% of the stomachs studied, which suggests a preference for them wherever they are common.

  In one study off the Australian coast, dugong tissue turned up in 15 of 85 tiger sharks. Adult dugongs carry scars from failed attacks. When tiger sharks are abundant, dugongs shift their microhabitats to match those of the shark's known prey. Dolphins respond to the risk in a simpler way, and often avoid regions where tiger sharks live.

  In 2006, near Hawaii, a group of tiger sharks was documented killing an ailing humpback whale. Tiger sharks also scavenge, and they have been recorded feeding on dead whales beside great white sharks. In the German Channel of Palau, they have been seen eating dead manta rays.

  Hawaiian waters add the strangest entries. Around those coasts, horses, goats, sheep, dogs, cats and brown rats are fairly common in stomach contents. In one case, two flying foxes were found inside a single shark. Off Orpheus Island in Queensland, a tiger shark being tagged regurgitated an echidna. Reaching prey like this, often at night, depends on a body full of specialized sensors.

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• 3. Built for the Dark

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  Small pits on the snout of a tiger shark hold electroreceptors called the ampullae of Lorenzini. These detect electric fields, including the faint impulses that living prey give off. A sensory organ called the lateral line runs along most of each flank and registers minute vibrations in the water. Together, the two systems let the shark find hidden prey in total darkness.

  A sharp sense of smell lets the shark follow faint traces of blood to their source. Its ability to pick up low-frequency pressure waves lets it advance with confidence even in murky water. Behind the retina sits a reflective layer called the tapetum lucidum. It gives light-sensing cells a second chance to catch photons, which helps in dim conditions. Like other sharks, the tiger shark has no movable eyelids. Instead, a clear nictitating membrane can slide across the eye.

  The skin runs from blue to light green on top, with a white or light-yellow underbelly. This pattern is called countershading. Prey looking down sees a shape blending into darker water, and prey looking up sees a pale belly blending into sunlit surface. The head is somewhat wedge-shaped, which lets the shark turn quickly to one side.

  The teeth are unmistakable. Each has sharp, pronounced serrations and a tip that points sideways. They are built to slice through flesh, bone and turtle shell. Relative to body size, they are shorter than a great white's, yet nearly as broad at the root. Rows of replacement teeth keep coming throughout the shark's life. The jaws are broad and heavily calcified, and the mouth sits almost at the front of the head.

  Tiger sharks swim slowly, and their coloring makes them hard to spot against dark backgrounds. Long fins give lift, and the long upper tail supplies bursts of speed. For the final approach, the shark circles its prey and prods it with the snout. Then it uses a rush to cover the last distance before the prey can escape. By day it keeps to deeper water, and at night it moves close to shore to feed. Despite the sluggish look, it is one of the strongest swimmers among the carcharhinid sharks.

  Only one natural predator has been recorded. Orcas hunt tiger sharks by holding them upside down, which induces tonic immobility, and then drown them. They bite off the fins before disemboweling and eating the shark. Apart from orcas, the species has no recorded enemy, so its greatest threats come from people.

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• 4. Names and Ancestors

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  In 1822, the naturalists Peron and Lesueur first described this shark and named it Squalus cuvier. In 1837, Müller and Henle renamed it Galeocerdo tigrinus. The genus name combines the Greek galeos, meaning shark, with kerdo, the word for fox. The species name honors the naturalist Georges Cuvier. Another colloquial name for the animal is the man-eater shark.

  The tiger shark belongs to the order Carcharhiniformes, the most species-rich order of sharks, with more than 270 species. Catsharks and hammerheads belong to it as well. Members share a nictitating membrane over the eyes, two dorsal fins, an anal fin and five gill slits. Within this crowd, the tiger shark stands alone. It is the only living member of the genus Galeocerdo and the only member of the family Galeocerdonidae.

  The oldest remains of Galeocerdo reach back to the Eocene epoch. Fossils of the modern species date to the Middle Miocene, around 13.8 million years ago.

  The animal's common name comes from the dark stripes along its body, which resemble a tiger's pattern. Those stripes fade as each shark matures, and adult bodies change in other ways too.

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• 5. Size and Life Cycle

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  One pregnant female caught off Australia reportedly measured 5.5 m and weighed 1524 kg. She was exceptional. A typical adult tiger shark measures 3.5 to 4.7 m and weighs between 300 and 900 kg. The International Game Fish Association's all-tackle record stands at 810 kg. Females are the larger sex. Mature females are often over 3.7 m, while mature males rarely reach that size, and the largest males measure about 4 m.

  A 7.4 m, 3110 kg tiger shark appears in some papers, but it is far bigger than any scientifically observed specimen and needs verification. A 2019 study suggested that tiger sharks of the Pliocene could have reached 8 m. Among living sharks, only the whale shark, the basking shark and the great white are larger on average. That makes the tiger shark the second-largest predatory shark. The great hammerhead can match its length but is lighter, with a maximum known weight of 580 kg from a heavily pregnant 4.4 m individual.

  Males reach sexual maturity at 2.3 to 2.9 m, and females at 2.5 to 3.5 m. Females mate once every three years. During mating, the male inserts a clasper into the female's cloaca to guide the sperm. He grips her with his teeth to hold her still, which often causes her considerable discomfort. In the Northern Hemisphere, mating generally falls between March and May, with birth between April and June the following year. In the Southern Hemisphere, mating happens in November, December or early January.

  A 2026 study identified Olowalu, Hawaii, as a mating site, the first ever pinpointed. The sharks gather there in the same winter period when North Pacific humpback whales mate and nurse their calves. The researchers suggest the sharks may be there to prey on those calves.

  Inside the mother, the tiger shark's story is unusual. It is the only ovoviviparous species in its family, so eggs hatch internally and the young are born live. Tiger sharks are also unique among sharks in using embryotrophy. The young develop in sacks filled with nourishing fluid, and they grow dramatically without any placental connection. Gestation lasts up to 16 months, and litters range from 10 to 80 pups. A newborn measures 51 to 76 cm. Lifespan is unknown, though tiger sharks can live longer than 12 years. Growth rates among juveniles also differ by region, with some growing close to twice as fast as others.

  A study by Hammerschlag and colleagues compared young and adult bodies. Juveniles have more conical heads, similar to those of requiem sharks, and larger tails. The big tail is theorized to help them dodge larger predators and catch quicker prey. With age the head grows broader, which suits a bigger bite on more varied prey. The tail becomes more symmetrical, which favors long-distance travel as the shark becomes more migratory.

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• 6. Ranges and Gatherings

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  Around the island of Fuvahmulah in the Maldives, researchers have recorded at least 239 individual tiger sharks. The count comes from a long-term study using photo identification and laser photogrammetry, methods that do not harm the animals. It makes Fuvahmulah the largest known aggregation of the species. Adult females show an especially strong loyalty to the site. Researchers suggest that warm water and a steady food supply there favor gestation.

  Elsewhere, the tiger shark is more often a wanderer. It is found near coasts in tropical and subtropical waters worldwide, and its movements follow warmer currents. In colder months, it stays closer to the equator. It favors deep water along reefs but enters channels to chase prey into the shallows. Some have been recorded at depths approaching 900 m.

  In the western Pacific, the shark has been found as far north as Japan and as far south as New Zealand. In the Mediterranean it is rare, but records exist off Malaga in Spain, Sicily in Italy and Libya. It is seen in the Gulf of Mexico, the Caribbean, along North American beaches and in parts of South America. Sightings also come from the waters off Africa, China, India, Australia and Indonesia.

  A University of Miami study found that warming Atlantic currents have pushed tiger shark migration paths further north.

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• 7. Sharks and People

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  Typically three to four shark bites occur per year in Hawaii, even though thousands of people swim, surf and dive there daily. One survivor is the surfing champion Bethany Hamilton, who lost her left arm to a tiger shark at age 13 in 2003. Encounters rise between September and November, when females are believed to migrate to the islands to give birth.

  The tiger shark ranks second behind the great white in recorded attacks on humans, and it is regarded as one of the most dangerous sharks. Even so, attacks are few and very seldom fatal. It often visits shallow reefs, harbors and canals, and it lives in river mouths and other runoff-rich water, which creates chances for contact.

  On the 8th of June 2023, a tiger shark killed a 23-year-old Russian man in the Red Sea off Hurghada, Egypt. Onlookers filmed the attack and the video went viral. Fishermen later caught and killed the shark. It was the third fatal tiger shark attack in the area since 2022.

  Hawaii once tried to solve the problem by force. Between 1959 and 1976, 4,668 tiger sharks were culled to protect tourism. The effort damaged the shark population, yet it did not reduce the number of encounters between people and sharks. Today feeding sharks in Hawaii is illegal, apart from traditional cultural or religious practices, and activities such as cage diving are discouraged.

  Elsewhere, people have chosen closeness. In a 2007 Discovery Channel special, the South African shark behaviorist Mark Addison showed that divers could swim with tiger sharks outside a cage. The underwater photographer Fiona Ayerst swam with them in the Bahamas. At Tiger Beach, off Grand Bahama, uncaged diving with female tiger sharks, and even handling them, has become routine. Those close encounters sit alongside a harsher relationship, since fishing fleets catch tiger sharks regularly.

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• 8. Fins, Liver and Skin

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  The International Union for Conservation of Nature lists the tiger shark as near threatened, citing excessive finning and fishing. Fishers kill the animal for its fins, flesh and liver, and it is caught regularly in both target and nontarget fisheries. Several populations have declined where fishing has been heavy.

  Shark fin has very few nutrients, but shark liver holds a high concentration of vitamin A, which goes into vitamin oils. The tiger shark's distinct skin is also prized, and big-game fishers pursue it for sport.

  In 2010, Greenpeace International added the tiger shark to its seafood red list, which names commonly sold fish likely to come from unsustainable fisheries. In June 2018, the New Zealand Department of Conservation classified the species as Migrant, with the qualifier Secure Overseas, under its Threat Classification System. Continued demand for fins may bring further declines, and that New Zealand label rests on the health of populations elsewhere.

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