By Blaise Jones
For the most part sharks are lone hunters, only interacting with other members of their species in disputes over food or during the mating season. However, there are some species that display a surprising amount of cooperation.
There are three species of shark that have been conclusively observed hunting in groups. The broadnose sevengill shark, the sand tiger shark, and the blacktip reef shark. All three of these species use similar methods of cooperative hunting when working together.
The broadnose sevengill shark is a large species that typically lives a solitary life. However, when these sharks attempt to prey upon a more dangerous animal, such as a cape fur seal, they gather in large groups. The large school of sharks surrounds the seal, preventing it from escaping. Then the school slowly begins to tighten the circle, pressing in on the seal from all sides.
Eventually one of the sharks runs in for a bite, usually from behind when the seal isn’t looking. From there the rest of the sharks begin to run in and take bites at the seal one by one until the seal becomes too weak to defend itself, at which point the sharks descend upon and devour it.
Sand tiger sharks and blacktip reef sharks use a similar method when they hunt in groups. A few sharks will swim along the outskirts of a large school of fish. The sharks will then herd the school of fish up against either the shore or some structure and block off their escape. From there the sharks take turns rushing into the school and attempting to catch some fish, while the other sharks continue to prevent the school of fish from escaping.
Cooperation or Coincidence?
While those three species of sharks are the only species that have been confirmed to engage in cooperative hunting, there are plenty of accounts of other species working together as well.
Species like the whitetip reef shark and smooth hound sharks have been observed hunting in large schools, sweeping over reefs at night like a swarm of marine locusts, forcing any and all prey out of hiding and increasing the chances of each shark getting a meal. Whether this mass gathering of hunting sharks is cooperative or coincidental is unknown. It could simply be that there are large numbers of these species occupying the area and that they all hunt around the same time.
Silky, dusky, and bronze whaler sharks have all also been seen engaging in behavior similar to how the sand tiger and blacktip reef sharks hunt. Thresher sharks have been observed working in pairs, with one shark corralling a small school of fish with its long tail while the other stuns the school with a whip of its tail.
Great white sharks have been seen coming and going from known hunting grounds in groups, often with an established alpha animal. These sharks have been observed hunting in the same areas and even seemingly sharing their caught prey with each other.
Great whites were once observed seemingly working together to move the carcass of a whale into deeper water, and there has been speculation that great whites might sometimes work together to bring down larger prey such as whales.
“Sharks: The Animal Answer Guide” by Gene Helfman and George H. Burgess
“The Encyclopedia of Sharks” by Steve A. Parker