Sharks: built for the ocean

Habitat

Coasts and open temperate seas

Food

Fish, rays and marine mammals

Size

Usually 4–5 m; some exceed 6 m

The great white uses a strong tail for steady cruising and bursts of speed. Dark skin above and a pale belly create countershading, making the shark harder to see from above or below. Rows of replacement teeth move forward when older teeth are lost.

Habitat

Warm tropical and subtropical seas

Food

Plankton, fish eggs and small fish

Size

Often 8–12 m; the largest living fish

Despite its enormous size, the whale shark is a gentle filter-feeder. It swims with its wide mouth open and strains tiny organisms from the water. Every whale shark has a unique pattern of pale spots, which researchers can use like a fingerprint.

Habitat

Warm coasts, reefs and open water

Food

Fish, squid and rays

Size

Usually 2.5–3 m long

Its wide, scalloped head places the eyes far apart and carries many sensors that detect tiny electrical signals made by living animals. This shape may improve turning and help the shark search a broad area of seafloor. Large groups sometimes gather near oceanic islands.

Habitat

Tropical and warm coastal seas

Food

Fish, turtles, seabirds and more

Size

Often 3–4.5 m long

Young tiger sharks have strong dark bars that fade as they grow. Their broad jaws and notched teeth can cut many kinds of food, including hard turtle shells. As wide-ranging predators and scavengers, they help move energy through tropical marine food webs.

Habitat

Offshore temperate and tropical seas

Food

Tuna, mackerel and squid

Size

Usually 2.5–3.2 m long

The shortfin mako has a pointed snout, a streamlined body and a crescent-shaped tail built for fast swimming. Special blood-vessel arrangements keep parts of its muscles warmer than the surrounding water. This helps it chase quick prey across the open ocean.

Habitat

Shallow reefs, seagrass and mangroves

Food

Crabs, molluscs and small fish

Size

Usually 2.2–2.7 m long

Nurse sharks often rest on the seafloor during daylight and search for food at night. Two small barbels near the mouth help them feel and taste the bottom. Strong throat muscles create suction that pulls hidden crabs, snails and fish from cracks.

Habitat

Shallow Indo-Pacific reefs and lagoons

Food

Reef fish, crustaceans and squid

Size

Usually under 1.6 m long

Bright black tips edged with white make this reef shark easy to recognise. It usually stays close to shallow coral, sand flats and lagoons instead of crossing wide oceans. Its brown back and pale belly provide camouflage, while a quick streamlined body helps it catch small reef animals.

Habitat

Deep continental slopes and seamounts

Food

Fish, squid and crustaceans

Size

Adults often 2.6–3.8 m long

The goblin shark lives mostly hundreds of metres below the surface. Its long flattened snout carries sensors that detect weak electrical signals from prey. When food comes close, special ligaments let the jaws shoot forward rapidly; visible blood vessels give the soft skin a pinkish colour.

Habitat

Temperate and tropical open seas

Food

Schooling fish and squid

Size

Often 4–5 m including the tail

The upper half of a thresher shark's tail can be almost as long as the rest of its body. It accelerates, swings the tail like a whip and stuns schooling fish before eating them. Despite its size, the shark has a small mouth and is generally shy around people.

Habitat

Indo-West Pacific reefs and sandy bottoms

Food

Molluscs, crustaceans and small fish

Size

Up to about 2.5 m long

Adult zebra sharks are yellow-brown with dark spots, body ridges and a tail almost as long as the body. Young sharks have bold stripes—the source of the name. They rest near reefs by day and become active at night, using suction to pull molluscs and crustaceans from crevices.