Basking sharks often spark curiosity about their nature, particularly whether their imposing size translates to a threat to humans. As the second-largest fish globally, these sharks are frequently observed near the surface. Despite their formidable appearance, basking sharks are known for their placid demeanor. They are not predatory towards large animals, including humans, and primarily engage in filter feeding.
Understanding the Basking Shark
Basking sharks, scientifically known as Cetorhinus maximus, are colossal, with adults reaching lengths between 22 and 29 feet (6.7 to 8.8 meters), though some individuals can exceed 33 feet (10 meters). Their diet consists exclusively of microscopic organisms called zooplankton, which they filter from the water. They favor small crustaceans like copepods. They swim with their cavernous mouths wide open, sometimes extending up to 3 feet (1 meter) across, to passively collect food.
Their enormous mouth is adapted for filtering, not for hunting or biting large prey. Their mouths contain numerous small, hooked teeth, only about 5-6 millimeters long, not used for tearing or chewing. Gill rakers, dark, bristle-like structures, line their gill slits, efficiently trapping plankton as water flows through. A large basking shark can filter up to 2,000 tons of water per hour.
Typical Behavior and Temperament
Basking sharks have a calm, non-aggressive temperament. They are often observed swimming slowly near the surface, a behavior that earned them their name, as they appear to be “basking” in the sun while actively feeding on dense plankton. Their cruising speed is around 3 miles per hour (5 kilometers per hour).
They are indifferent to human presence and not territorial. While they can be solitary, basking sharks sometimes gather in groups, ranging from small clusters to large aggregations of over a hundred, especially in areas rich with zooplankton. They undertake extensive seasonal migrations, traveling thousands of kilometers to follow plankton blooms, sometimes crossing entire ocean basins. Basking sharks have also been observed breaching, or leaping partially out of the water, a rare but natural behavior unrelated to aggression.
Documented Human Encounters
The historical record shows no verified cases of unprovoked attacks on humans by basking sharks. Organizations like the International Shark Attack File (ISAF) have no confirmed reports of basking sharks harming people. Despite their considerable size and occasional presence in coastal waters, these filter feeders do not perceive humans as prey.
While their nature is gentle, their immense size and rough skin mean that accidental interactions can occur. There is one recorded incident from 1937 where a breaching basking shark reportedly capsized a boat in Scotland, leading to the drowning of three passengers. This event, however, is considered an isolated accident rather than a predatory act. Contact with their skin can cause abrasions, so maintaining a respectful distance is always advised.