There's a reason orcas are called the "wolves of the sea": not only are the four-ton behemoths true top predators, but like their canid namesakes, they also hunt in packs. During a recent whale-watching tour, a photographer in California's Monterey Bay captured rare footage of killer whales feasting on shark.

The clip was captured by Slater Moore of Monterey Bay Whale Watch, who believes the prey species to be a sevengill shark (Notorynchus cepedianus). The Eastern Pacific's "offshore" killer whales specialise in hunting sharks and bony fish, so the kill – though extraordinary to see – is actually quite normal. Offshore orcas are so good at nabbing sharks, in fact, that certain populations have been known to wear their teeth to the gums on their rough skin.

Shark skin is covered in tiny, tooth-like structures called "dermal denticles". The modified scales allow sharks to move seamlessly through the water, but for the whales who feed on them, they mean dental disaster. To get to the oily meat and organs within a shark's body, killer whales essentially have to gnaw through sandpaper. (Denticles can also cause "shark burn" in humans!)

Shark skin causes a dental disaster for the offshore killer whales that feed on them.  Image: Rod Palm/Aquatic Biology

Shark-eating orcas tend to hunt deep underwater, so footage like this can help us learn more about how a particular group disperses food. "The drone offers a unique perspective," adds the team. "It is very likely that some of these whales have only been sighted a few times or haven't been identified at all – we may go over five years between sightings!"

We tend to associate food-sharing with terrestrial animals like wild dogs, but the practice is actually quite common among orcas. This pod had a few small calves in tow, which could also explain the behaviour. 

Salmon-eating killer whales have been known to hold fish in their mouths so the youngest pod members can nibble away, and scientists have seen similar behaviour in seal-eaters. A pod's matriarch typically has her fill before other members are given a turn, so that's likely what we're seeing here. 

And even for all-adult pods, passing around prey can be beneficial. Ensuring that every member of the hunting party is healthy helps secure meals for the group down the line.



Top header image: Matthew Allen/Flickr