Swiss Army Knife teeth secret to seal's success

October 30, 2012
Swiss Army Knife teeth secret to seal's success

Biologists have shown how an advanced set of teeth give Antarctic leopard seals the biological tools to feast on prey of all sizes, from penguins to tiny krill.

The seals are infamous for their 'grip and tear' feeding tactics where they shake penguins and larger prey while holding them between their long front teeth. Now, researchers from Monash University and Museum Victoria have documented for the first time, in , how they use side teeth to sieve five centimetre-long krill from seawater.

David Hocking, a PhD student in the Monash School of Biological Sciences who has been studying the , said exactly how seals ingested the krill had been a puzzle.

"The classic filter feeders of the ocean are the mysticete whales, such as the humpback and , that use specialised baleen as a filter to sieve for krill. But leopard seals don't have baleen," Mr Hocking said.

To work out how leopard seals, which can reach up to 500 kg in the wild, are able to feed on such tiny prey, the team performed feeding trials with the species at Taronga Zoo in Sydney.

The researchers showed that the seals generate suction with their tongues to draw prey into their mouths. The excess water is then forced out of the corners of the mouth while the food is retained behind a sieve created by the cheek teeth.

Dr Alistair Evans, also of the Monash School of Biological Sciences, said the seals' ability to use their cheek teeth as a sieve had been suspected, but never observed.

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

Museum Victoria's Dr Erich Fitzgerald said the seals were supremely well adapted to their .

"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," Dr Fitzgerald said.

The seals' ability to switch diets depending on seasonal abundances of may be key to their success in the harsh Antarctic environment.

"These are one of last truly abundant large mammalian predators remaining in the wild, with numbers possibly as high as 100,000 around Antarctica," Mr Hocking said.

"However, their dependence on krill may also be a weakness due to krill's susceptibility to climate change and potential as a commercial fishing target. In the future, it's likely these amazing predators will be at great risk, along with other iconic Antarctic fauna."

Explore further: Antarctic krill provide carbon sink in Southern Ocean

Related Stories

Antarctic krill provide carbon sink in Southern Ocean

February 6, 2006

New research on Antarctic krill (Euphausia superba), a shrimp-like animal at the heart of the Southern Ocean food chain, reveals behaviour that shows that they absorb and transfer more carbon from the Earth’s surface than ...

Penguins that shun ice still lose big from a warming climate

April 11, 2011

Fluctuations in penguin populations in the Antarctic are linked more strongly to the availability of their primary food source than to changes in their habitats, according to a new study published online today in the Proceedings ...

Record number of whales, krill found in Antarctic bays

April 27, 2011

Scientists have observed a "super-aggregation" of more than 300 humpback whales gorging on the largest swarm of Antarctic krill seen in more than 20 years in bays along the Western Antarctic Peninsula.

Changes in krill abundance inferred from antarctic fur seal

December 1, 2011

It is possible to know a tree from its fruit, but is it possible to know a prey from its predator? The answer is YES with Antarctic krill and Antarctic fur seals. Scientists of the University of Science and Technology ...

Recommended for you

Genomes uncover life's early history

August 24, 2015

A University of Manchester scientist is part of a team which has carried out one of the biggest ever analyses of genomes on life of all forms.

Rare nautilus sighted for the first time in three decades

August 25, 2015

In early August, biologist Peter Ward returned from the South Pacific with news that he encountered an old friend, one he hadn't seen in over three decades. The University of Washington professor had seen what he considers ...

Why a mutant rice called Big Grain1 yields such big grains

August 24, 2015

(Phys.org)—Rice is one of the most important staple crops grown by humans—very possibly the most important in history. With 4.3 billion inhabitants, Asia is home to 60 percent of the world's population, so it's unsurprising ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.