Can dolphins kill sharks? Killer whale hunts and group defense

Yes, in the sense that killer whales belong to the dolphin family Delphinidae alongside pilot whales and relatives. National Geographic reports a pod of killer whales killing a young white shark. Dolphins also defend one another by chasing and ramming an attacking shark as a group.

“Dolphin” names a family rather than one animal. None of the Animal Diversity Web, Whale and Dolphin Conservation, National Geographic or Ecology sources behind this article records a dolphin other than a killer whale killing a shark.

What happened when killer whales took on a white shark

National Geographic describes the episode this way: “A pod of killer whales chased a young great white shark, immobilized it and then bit its liver out of its body.” The hunting session lasted about 30 minutes and the pod took down two sharks. A young great white of that size is usually around 6.5 feet long, the same account notes.

About two minutes later, one of the whales came back with the liver, which the same account describes as fatty and rich in calories. That account says the shark would be paralyzed while held that way, which makes it easier for the whales to take bites from their prey without being bitten back. The hunt was published in the journal Frontiers in Marine Science.

Why killer whales are in a position to attack

Small sharks are a target for some killer whale populations, according to Whale and Dolphin Conservation. Killer whales often hunt in packs, and Animal Diversity Web says they work together and signal to each other when they take prey larger than themselves.

An adult male killer whale averages 8 m in length, and the average weight for a male is 7200 kg, both figures from Animal Diversity Web. One National Geographic caption places them in the Sea of Cortez, off the coast of Baja California Sur, Mexico.

How white sharks respond after an attack

National Geographic reports that when one shark is taken by killer whales, the rest of the population leaves the area. White sharks have left gathering sites in South Africa because of killer whale attacks. A great white shark reaches 6 m long and weighs up to 3000 kg, according to Animal Diversity Web, and its mouth measures 0.9 to 1.2 m wide.

A study in Ecology reports what happened to white sharks in one area. A group of killer whales killed at least two and possibly three white sharks there, over a stretch of around 71 minutes. The study sets out three kinds of evidence, and on that basis its authors suggest the white sharks left at once and stayed away for at least 7 weeks.

How dolphins defend themselves from shark attacks

Their strong snouts are the weapon they use, rammed into the soft underbellies and gills of a shark to cause injuries, Whale and Dolphin Conservation says. Echolocation lets bottlenose dolphins locate predators, Animal Diversity Web says.

Shark attacks still take a toll. Whale and Dolphin Conservation reports that large sharks prey on dolphins and especially target very young calves and sick adults, which are the weakest individuals. In the resident Sarasota, Florida community, one third of the dolphins carry scars from shark bites. Animal Diversity Web notes that seeing dolphins with shark bites is not uncommon, which demonstrates their survival of an attack.

What it means for shark and dolphin populations

White sharks reach maturity slowly, live long lives and produce few offspring. Animal Diversity Web says many shark populations have fallen by up to 80 percent since 1970, and that some dolphin populations may now face less predation from sharks.

Common bottlenose dolphins give a sense of scale. Adult males of the species typically run 244 to 381 cm and weigh about 500 kg, while adult females are usually 228 to 366 cm long and weigh about 250 kg. Bottlenose dolphin groups usually range from a few individuals to over 100, and common bottlenose dolphins can swim up to 30 km/hr, though they average between 3 and 6 km/hr.