The leopard seal (Hydrurga leptonyx), one of Antarctica’s apex predators, kills penguins and smaller seals in a violent yet efficient manner. However, it seems that that’s not the only thing that H. leptonyx eats. A new study reports that H. leptonyx uses suction feeding to eat large amounts of krill, which is akin to how whales eat krill as well.
The scientists reported their findings in the journal Polar Biology. David Hocking, from Monash University in Melbourne, Australia, and his colleagues have shown how H. leptonyx eats krill, by sucking them into its mouth and sieving them through special teeth. This behavior was predicted from the shape and arrangement of the seal’s teeth, but this is the first time it had been observed and filmed.
This allows H. leptonyx to dine from the top and bottom layers of the Southern Ocean’s food web. This could explain why leopard seals are such successful predators. The animals’ trident-shaped postcanine teeth are similar to those of ancient whales, like Janjucetus hunderi, which lived during the late Oligocene. This could indicate that J. hunderi did the same.
Taronga Zoo in Sydney, Australia, is the only institution in the world that houses leopard seals. The seals were presented with small fish sticking out of a plastic box. The seals quickly sucked the fish out and expelled the excess water through the sides of their mouths.
Krill could consist up to 83% of a leopard seal’s diet in regions where larger prey are in shorter supply. One dissected individual had more than 10,000 freshly caught krill in its stomach.
Reference: “Leopard seals (Hydrurga leptonyx) use suction and filter feeding when hunting small prey underwater” by David P. Hocking, Alistair R. Evans and Erich M. G. Fitzgerald, 20 October 2012, Polar Biology.