What is a Basking Shark?

Mary McMahon
Mary McMahon

A basking shark or Cetorhinus maximus is an oceangoing fish. Basking sharks are among the largest fish in the world, with specimens averaging around 33 feet (10 meters) in length. They share some physical traits with their shark relatives, but unlike other large sharks, they are not dangerous to people.


These fish are found in temperate waters all over the world, usually close to the shoreline. They are known as basking sharks because they have a habit of feeding and living near the surface, appearing to bask in the sun and warmer water. They can range in color from grayish to black, and are often mottled in color. Basking sharks are very slow swimmers, in part because of their large bulk.

This shark species is a filter feeder. It relies on marine microorganisms like krill for survival and does not seek out prey like fish. While basking sharks have teeth, they are small and poorly formed and do not pose a threat. They can be dangerous in close quarters because they may accidentally cause injuries with their sheer size, and there have been some recorded cases where people have collided with basking sharks in small boats and their craft have sustained damages.

Basking sharks have a distinctive pointed snout and very large gills that wrap almost entirely around the head. They have triangular dorsal fins that sometimes lead people to confuse them with their more dangerous cousins, and their rear fins are lunate, meaning that they are shaped roughly like a waxing or waning moon, depending on which side the basking shark is viewed from. One of the most notable features of the basking shark is the massive jaw. When they feed, the sharks drift through the water with their mouths open, filtering the seawater to pick out organisms to eat.

The basking shark is an ovoviviparous fish. The eggs are fertilized inside the female shark and she carries them with her while the embryos develop. When they are ready to hatch, they are born as live young. This method of reproduction is used by many other sharks as well.

Several notable cases of mistaken identity have involved basking sharks. Aside from cases where people confuse a basking shark with a more dangerous species because they are not familiar with these sharks, there have been some instances where deceased sharks have been misidentified as other ocean animals. Several cases of “mystery animals” that wash up on shore or are found at sea later turn out to be basking sharks.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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