Watch these orcas work together as a team to kill a tiger shark using tonic immobility.
By Blaise Jones
While sharks are amazingly efficient hunters and occupy some of the higher trophic levels in their ecosystems, this does not make them invincible. Almost every single species of shark faces predation, including the fearsome and huge great white shark.
A Family Meal
What creatures could threaten sharks? Turns out, most anything bigger than them. The most common predatory threat sharks face are larger sharks. Tiger, sleeper, bull, and great white sharks are some of the most common shark hunting smaller sharks. Bull sharks especially are known to hunt other sharks.
But not all shark-on -shark violence occurs out in the wild. Some species of shark start their cannibalism early. Both tiger and sand tiger sharks begin cannibalizing their siblings inside the womb. While gruesome, this behavior does have a purpose. The energy these cannibalistic siblings get from eating their brood-mates allows them to grow faster and have a better chance of survival upon being born.
Fish Aren’t Always Friends
However, bigger sharks aren’t the only fish that have it out for sharks. Many bony fish prey upon sharks. In fact, any bony fish that can swallow a shark is a potential predator. It’s only the above-average size of sharks as a species that keeps them from routinely being prey upon by bony fish.
However, there are some species of bony fish that grow large enough to prey upon sharks. Goliath grouper can grow up to 8 feet (2.4 m) long and weigh as much as 800 pounds (363 kg), making them large enough to prey upon sharks, which they have been observed doing.
Sometimes the fish don’t have to be bony at all. A giant pacific octopus in the Seattle Aquarium was filmed killing and eating several sharks that were in its tank.
It’s not just fish that sharks have to watch out for. A whole slew of marine organisms like to munch down on a nice tasty shark. The largest group of shark predators, aside from sharks themselves, are marine mammals.
The most frequent shark hunters are the orca (killer) whale and the sperm whale. In fact, these animals hunt sharks so frequently that if a shark hears their telltale echolocation, they swim away as fast as they can.
Smaller species of sharks even face threats from unlikely sources. Horn sharks and shy sharks have been seen being preyed upon by seals and sea lions.
Some marine mammals kill sharks without even eating them afterward. Dolphins and porpoises have been observed ramming sharks in the gills and bellies to the point of death. This behavior by the dolphin is often to force the rival predator out of the area. Usually, the shark will retreat, battered but alive. However, sometimes the dolphins will ram the sharks so much that they end up dying from internal bleeding.
Of course, the biggest mammalian predation threat sharks face is from humans. Each year more than a 100 million sharks are killed by the fishing industry. Many of them are harvested for their fins which are used to make shark-fin soup, a delicacy in many Asian nations. And the scary thing is, one hundred million is the conservative estimate. Researchers speculate that the number could reach well over two hundred million sharks. Without reliable sources of data, the number of sharks people kill each year will always be uncertain.
The worst part: 100 million is an estimate that is considered to be conservative by some. Researchers speculate that the number could reach well over 200 million sharks. Without reliable sources of data, the number of sharks people kill each year will always be uncertain.
That leads to another question: when sharks do get attacked – how do they defend themselves? Here’s the answer: defense strategies of sharks
See this Goliath grouper eat a 4-foot shark in gulp!
Sharks: The Animal Answer Guide by Gene Helfman and George H. Burgess
The Encyclopedia of Sharks by Steve Parker
The Secret Life of Sharks by Dr. A. Peter Klimley