Leopard seals (Hydrurga leptonyx) are unusual among apex predators in that they feed at both the top and near the bottom of marine food webs; they capture and consume marine amniotes (seals and penguins) as well as krill.
By switching between two feeding styles, the leopard seal can dine from both the top and bottom of the Southern Ocean’s food web.
David Hocking from Monash University in Melbourne, Australia, and his colleagues have shown that the leopard seal eats krill like a whale, by sucking them into its mouth and sieving them through special teeth.
Suction was used to draw small prey into the mouth followed by expulsion of ingested seawater through the sieve formed by postcanine teeth. Individuals show abrasive wear on canines and incisors, but not postcanines.
This suggests that postcanines are not systematically used for piercing prey during macrophagous feeding, confirming that the postcanines primarily serve a sieving function.
This is equivalent to a lion hunting down zebras, but also regularly feasting on ants or termites.
—Erich Fitzgerald, Museum Victoria, Melbourne