Whale Shark

Whale Shark facts at a glance

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The largest fish in the ocean

The whale shark is a true shark, not a whale, and the biggest fish alive today. Typical adults measure around 12 m, but the largest confirmed individuals approach 18 m and weigh up to roughly 19,000 kg. Its broad, flattened head and enormous mouth, which can stretch well over a metre wide, sit right at the front of the body. Each animal carries a unique pattern of pale spots and stripes on grey skin, allowing researchers to identify individuals like a fingerprint.

Filter feeding on plankton

Despite its size, the whale shark eats some of the smallest prey in the sea. It is a filter feeder, taking in plankton, fish eggs, krill, and small fish by opening its huge mouth as it swims or by hanging vertically to suck in dense patches of food. Water passes out through the gills while fine sieve-like pads trap the food. A feeding whale shark can filter thousands of litres of water an hour, and it has no need for the large teeth of a hunting shark.

How it swims and moves

Whale sharks are slow, deliberate swimmers, cruising at only about 5 km/h by sweeping the whole body from side to side. They are highly migratory, crossing entire ocean basins to reach seasonal feeding grounds where plankton blooms. Individuals dive to depths of over 1,000 m yet spend much time near the surface where food is richest. Their unhurried movement and surface feeding make them one of the easiest large sharks for divers to swim alongside.

Range and gatherings

Whale sharks live in warm open and coastal oceans around the tropics and subtropics, usually where surface temperatures stay above about 21 degrees Celsius. At certain times of year they gather in large numbers at predictable sites, such as off Western Australia, the Yucatan, and the Philippines, drawn by seasonal food. These aggregations are among the great wildlife spectacles of the sea. Outside such gatherings they tend to roam alone across vast stretches of ocean.

Life cycle and lifespan

Whale sharks are slow to mature, thought to take around 25 to 30 years to reach breeding age, and may live 70 to 100 years. Females give birth to live young, carrying hundreds of embryos that hatch from eggs inside the body and are born as small pups. Very few newborns are ever seen, and much of the species' early life remains a mystery to scientists. This slow, late reproduction makes the population very sensitive to losses.

Why it is endangered

The whale shark is listed as Endangered by the IUCN, with numbers falling over recent decades. It is threatened by fishing for its fins and meat, by ship strikes as it feeds near the surface, and by entanglement in nets. Its slow growth and late breeding mean populations recover only very slowly once reduced. Regulated tourism and international trade protection now play a growing part in its conservation.

Did you know? Whale Shark facts

• The whale shark is the largest fish in the world, reaching up to about 18 m.
• Despite its size, it feeds on tiny plankton by filter-feeding.
• Each whale shark has a unique pattern of spots, used to identify individuals.
• They are gentle and harmless to humans, often allowing divers to swim alongside.
• Whale sharks gather in large numbers where plankton or fish spawn is abundant.
• They are endangered, threatened by fishing and ship strikes.

Diet & feeding

Whale sharks filter-feed on plankton, krill, fish eggs, and small fish, straining prey from large volumes of water through specialised gill pads.

Adaptations

• Specialised filter pads strain plankton and small fish from huge volumes of water. (Compagno 2001)
• An enormous mouth and gill apparatus enable efficient filter-feeding.
• A patterned skin provides camouflage and individual identification.
• A large, slow-moving body suits long migrations between feeding hotspots.

Behaviour & ecology

• Whale sharks filter-feed at or near the surface, sometimes feeding vertically.
• They aggregate seasonally at sites of high plankton or fish-spawn density.
• They undertake long-distance migrations across ocean basins.
• Generally solitary, they tolerate one another at rich feeding sites.

Communication

• Whale sharks are not known for vocal communication.
• Aggregations are driven by shared food cues rather than social signalling.
• They rely on keen senses to detect plankton blooms and spawning events.

Habitat & range

Whale sharks roam warm tropical and temperate oceans worldwide, frequenting coastal feeding hotspots and open water, often near the surface.

Ecological role

As the ocean's largest filter-feeder, the whale shark links plankton production to the broader food web and is a flagship for open-ocean conservation.

Conservation status of the Whale Shark

Sources & references

This guide is compiled and reviewed against established zoological and conservation references. Key sources for the Whale Shark:

• IUCN Red List of Threatened Species

  Conservation status (Endangered) reflects the IUCN Red List category for Rhincodon typus.

• Pierce, S. J. & Norman, B. (2016). Rhincodon typus. IUCN Red List of Threatened Species.

  Status (Endangered) and threats.

• Compagno, L. J. V. (2001). Sharks of the World. FAO Species Catalogue for Fishery Purposes.

  Taxonomy and feeding biology.

• Froese, R. & Pauly, D. (eds.). FishBase — Rhincodon typus.

  Size, distribution, and biology.

• Global Animal Guide editorial standards

  How we research, source, review, and update every guide for accuracy.