Tiger shark

Tiger sharks eat lots of different foods.

They catch fish, sea turtles, squid and sea birds. They also eat dead animals they find in the sea.

Tiger sharks have one of the widest diets of any shark. They eat bony fish, rays, other sharks, sea turtles, squid, crustaceans, sea birds and even dolphins. They also eat dead animals they find.

They are not picky at all. Scientists sometimes find trash in their stomachs, such as cans and plastic, swallowed by mistake in harbors where garbage ends up in the water.

The Florida Museum calls the tiger shark perhaps the least discriminating feeder of all sharks. Prey varies by region but commonly includes sea turtles, rays, other sharks, bony fishes, seabirds, dolphins, squid, crustaceans and carrion. Its heavily serrated teeth, combined with a sawing, side-to-side shake of the head, let it cut pieces from animals much larger than itself.

Objects of human origin are often recovered from tiger sharks caught in harbors and river mouths. One female from the Gulf of Aqaba had swallowed two cans, a plastic bottle and two sacks along with a squid and a fish, a reminder of how marine debris reaches large predators.

Tiger sharks often hunt at night.

Their eyes work well when it is dark. They can also feel tiny movements in the water around them.

Tiger sharks hunt mostly at night, so their senses matter. Like other sharks, they have a shiny layer at the back of each eye that bounces light back through it, which helps them see in dim water.

A line of tiny holes along each side of the body, called the lateral line, feels movements in the water. Tiny pores on the head, called ampullae of Lorenzini, can sense the weak electric signals that other fish give off.

Fisheries and Oceans Canada describes the sensory kit sharks share. Behind the retina lies the tapetum lucidum, a layer of plate-like cells packed with reflective guanine crystals that sends light back through the retina, boosting vision in low light. That matters for a hunter that, according to the Florida Museum, feeds mostly at night.

The lateral line, canals of sensory neuromasts opening through pores along the body, detects water movement and sound. The ampullae of Lorenzini, gel-filled pores around the head, detect the tiny electric fields made by the muscles of nearby animals, though only at close range, which helps a shark find prey hidden in sand (University of Texas Marine Science Institute). Fisheries and Oceans Canada adds that they may also sense changes in water temperature.

Tiger sharks swim slowly most of the time.

When they spot food, they can zoom forward fast. They travel to cooler seas in summer and back to warm seas in winter.

A tiger shark usually cruises slowly, but it can burst forward with a quick rush of speed to catch its food by surprise. It mostly hunts alone and at night, when it moves closer to the shore and the surface.

Tiger sharks are great travelers. In warm months many swim from the tropics into cooler seas, and in winter they head back. Some make long journeys across the open ocean between islands.

Although large and usually slow-moving, the tiger shark is an effective ambush predator that uses short bursts of speed. It hunts alone, mainly at night, moving inshore and nearer the surface. Groups do form, but the Florida Museum suggests they gather around food rather than for social reasons. It migrates seasonally, into temperate waters in summer and back to the tropics in winter, and makes long oceanic crossings between islands.

The Florida Museum reports that tiger sharks are often curious and unaggressive when met, but it also lists the species second only to the white shark in reported bites on people, and advises treating it with caution and respect.

There are fewer tiger sharks than before.

People catch too many of them in fishing nets and on hooks. Fishing is the biggest danger for them.

The tiger shark is listed as Near Threatened, which means it could become endangered in the future. Its numbers are going down.

The main problem is fishing. People catch tiger sharks for their fins, meat and oil, and many are caught by accident on lines and nets set for other fish. Young sharks have been hit especially hard in some places.

The IUCN assessed the tiger shark in August 2018 (published 2019) as Near Threatened under criteria A2bd+3d, with a decreasing population; fishing and harvesting are the listed threat. It is taken directly for fins, flesh and liver oil and as bycatch in commercial and recreational fisheries. In the United States it is the third most commonly caught of the large coastal sharks.

The Florida Museum reports that catch rates in the mid-Atlantic have fallen since the mid-1980s, and observer data suggest that heavy fishing, especially of juveniles, has reduced the population there. With a generation length of about 17.5 to 22.5 years (IUCN), losses are slow to replace.