Whale Sharks: The Ocean's Largest Fish

The whale shark (Rhincodon typus) is the largest fish known today.

Whale sharks are long-lived. A 2020 radiocarbon study validated ages up to 50 years, but their maximum lifespan remains uncertain. Despite their enormous size and wide mouths, they are filter feeders. Their diet consists mainly of plankton, including microscopic animals and plants, along with tiny shrimp and small fish.

Whale sharks live in warm and temperate waters, mainly around the equator, and migrate with the seasons in search of food. Some visit the Red Sea in spring, so a chance encounter in Israel is not as unusual as you might think. In 2009, researchers counted up to 420 whale sharks in a single aerial survey off Mexico’s Yucatan Peninsula, feeding on little tunny eggs.

A whale shark’s mouth can reach about 1.5 meters across, making it well suited to filter feeding. Inside are filtering pads and hundreds of rows of tiny teeth. Five large gill slits on each side allow filtered water to flow out. Small eyes sit on either side of its broad, flat head.

The body is mostly gray, with a white belly and a pattern of pale yellow spots and stripes across the back. Each shark has its own pattern, helping researchers identify individuals and count populations. Its skin can be around 10 cm thick. The fins have a familiar shark shape: a pair of pectoral fins, a prominent dorsal fin, and a long, powerful tail.

Like other sharks, the whale shark is a vertebrate with a skeleton made of cartilage rather than bone. That gives it the flexibility to move with surprising ease despite its immense size and weight.

Seeing a whale shark is a memorable experience for any diver. These filter feeders may swim near people, but an encounter is not an invitation to interact.

Some feeding sites attract whale sharks seasonally, supporting wildlife tourism, but sightings are not guaranteed. Follow local encounter rules, give the shark room, and never touch, chase, feed, or block it. Stay clear of its tail.

Only specialized aquariums can accommodate whale sharks and meet their space and feeding needs.

Whale sharks give birth to live young that develop from eggs retained inside the mother. A female caught off Taiwan in 1995 carried about 300 embryos at different stages of development. Much of their reproductive biology remains poorly understood.

Whale sharks mature slowly, and estimates of maturity differ between males and females.

Whale sharks are listed as Endangered on the IUCN Red List. Fishing and vessel strikes remain threats. In 1998, the Philippines banned the fishing, sale, import, and export of whale sharks for commercial purposes. India introduced protection in 2001, and Taiwan later restricted catches.