Antarctic crabeater seals (Lobodon carcinophaga) have some of the strangest teeth in Nature!
But rather than feeding on actual crabs, these unusual seals eat Antarctic krill (Euphausia superba) which are super abundant in the cold waters around Antarctica. Such tiny prey are challenging for large animals to eat and led the whales to forego teeth altogeather in favour of a hair-like baleen sieve.
Crabeater seals did something similar, adapting their cheek teeth to form a complex lattice-like filter!
Krill are sucked into the mouth before the jaw snaps shup - trapping the krill within the cage created by the teeth. The water is then forced out of the mouth by the tongue, while the prey items are trapped inside ready for swallowing!
Specimen Information: NMVC7385, (Museums Victoria).
Reference: Klages & Cockcroft 1990 Feeding behaviour of a captive crabeater seal. Polar Biol 10:403–404.