The mouth of a crabeater seal is uniquely adapted to feed on Antarctic krill by acting like a sieve. A hungry crabeater will take a mouthful of water, close its jaws, squeeze the water out through its teeth and filter out all the krill, which it then consumes. These microscopic krill comprise over 90% of the crabeater seal's diet (despite its name, the crabeater seal does not actually feed on crabs). As Stanley explains, "the same thing that sustains 100,000 of these [crabeater seals] also sustains the 100-foot-long blue whales." Surprised? Don't be. With an estimated biomass of 500-million tons, Antarctic krill are, by some estimates, the most abundant animal species on the planet.

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More nightmarish dentition here.

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[The Brain Scoop via Aatish Bhatia]