Antarctic Leopard Seals Switch Diet to Survive

A new study sheds light on the Antarctic leopard seals' food habits in a harsh environment and how they consume smaller prey.

Leopard seals, one of Antarctic's top predators, feed on penguins and smaller seals. They are known for their "grip and tear" technique, wherein they shake the larger prey while holding them between their front teeth.

It was a mystery as to how the seals gulped down smaller prey. For the first time, a team of researchers from Monash University and Museum Victoria in Australia has found evidence showing seals consuming smaller prey like krill, using an advanced set of teeth.

The research team performed feeding trials with leopard seals at Taronga Zoo in Sydney. They gave the resident seals, Casey and Sabine, four small fish with their head sticking out of a plastic box to which they were tied.

They found that the seals sucked their prey with their tongues and grabbed it into their mouth. While excess water was removed out of the mouth corners, their cheek teeth sieved the prey.

"These seals use their front teeth - canines and incisors - to capture and kill large prey. But their long multi-cusped cheek teeth act as a sieve, similar to what we see in filter-feeding whales," said Alistair Evans, from the Monash School of Biological Sciences.

This is the first time researchers have documented how seals consume their prey. They noted that the species can switch between the two feeding methods and can catch prey "from both the top and bottom of the Southern Ocean's food web," a report in Nature said.

"This is equivalent to a lion hunting down zebras, but also regularly feasting on ants or termites," Erich Fitzgerald from Museum Victoria, who was involved in the study, was quoted as saying by Nature.

"What we are seeing here is a large predator that can eat penguins at one time of year, and then switch to krill when there's no big prey around," Fitzgerald said.

This ability of the seals to switch between different diets could help them survive in the harsh environment of Antarctica.

Researchers also noted that the seals' dependence on krill as prey could pose a great risk to them in the future, as krill is prone to climate change and is also a fishing target.

The findings of the study are published in the journal Polar Biology.

To look at how leopard seals suck down fish, click here.