Great White Shark

The great white shark is the largest predatory fish on Earth and one of the most misunderstood animals in the ocean. It is not a mindless killing machine and it is not common — it is a slow-growing, slow-breeding apex predator that has become a conservation concern across much of its range.

Overview

Great whites belong to the mackerel shark family, which also includes the mako and porbeagle. They are found in cool and temperate seas worldwide, spending time both close to shore — near seal colonies and reefs — and far out in the open ocean, where tagged sharks have crossed entire ocean basins and dived below 1,000 m.

Physical characteristics

The great white’s body is a classic fast-predator shape: a stiff, torpedo-like trunk, a tall first dorsal fin, and a nearly symmetrical crescent tail that provides efficient thrust. The back is grey to bronze and the belly is white — countershading that makes the shark hard to see from above against the dark seabed and from below against the bright surface.

Its jaws hold several rows of large, triangular, serrated teeth that are continuously replaced. A shark may get through many thousands of teeth in its lifetime.

Great whites are regional endotherms. A network of blood vessels called the rete mirabile recycles metabolic heat, keeping the muscles, gut, brain and eyes up to about 14 °C warmer than the water. That warmth translates into faster swimming and quicker reactions in cold, prey-rich seas.

Senses

Great whites hunt with an unusually complete sensory toolkit:

• Smell can detect prey odours carried on currents from hundreds of metres away.
• The lateral line feels pressure waves from struggling or swimming animals.
• Electroreception through jelly-filled pores (ampullae of Lorenzini) picks up the tiny electrical fields of muscle activity at close range, guiding the final strike even in murky water.
• Their eyesight is good, and they can roll the eye back or use a protective membrane during contact.

Diet and hunting

Young great whites eat fish, rays and smaller sharks. As they grow past about 3 m, they shift toward marine mammals — seals, sea lions and dolphins — plus scavenged whale carcasses, which can draw several sharks to feed together. Around Cape seal colonies, great whites use a vertical ambush: they patrol deep and dark, then rush upward and strike the silhouette of a seal at the surface, sometimes breaching completely.

Hunting success depends heavily on surprise. Seals that spot a shark early can usually out-turn it.

Reproduction and life cycle

Great whites reproduce very slowly, which is the core of their conservation problem. Females mature at around 4.5–5 m and roughly 26 years old. They are ovoviviparous: eggs hatch inside the mother and the pups are nourished in part by eating unfertilised eggs (oophagy). After a gestation thought to last well over a year, a female gives birth to a small litter — typically 2 to 10 pups of about 1.2–1.5 m — then may rest for a year or more before breeding again.

Threats and conservation

The great white is listed as Vulnerable globally. Because there is no reliable worldwide population estimate, the trend is officially unknown, but several lines of evidence point to long-term declines. Threats include:

• Bycatch in commercial fisheries — nets and longlines set for other species.
• Targeted killing for jaws, teeth and fins, and historically for trophies.
• Beach protection programmes using nets and drumlines.
• Depletion of prey and coastal habitat degradation.

The species is protected in the waters of South Africa, Australia, the United States, the EU and elsewhere, and some regional populations — notably off the north-east USA and parts of Australia — show signs of slow recovery where seal populations have rebounded and protection has held.