Crabeater Seal

Photograph By: Jeffrey Kietzmann, National Science Foundation

 

Description & Characteristics:

One of the world’s most abundant large mammals, Crabeater seals' numbers have increased enormously in the last 50 years most likely due to declining whale populations. Inhabiting the shifting pack ice which surrounds the Antarctic continent, comparatively little is known about their behavior due to the difficulty of establishing scientific field stations on the ice.

Crabeaters are mostly dark grey in appearance, but in summer the coat can bleach almost to white. In general, they are lighter on the bottom (their ventral side) and darker on the top (their dorsal side). Their faces are dog-like and they have characteristic chocolate-brown markings and fleckings on the shoulders, sides and flanks.


Crabeaters are misnamed, since they actually eat krill, not crabs, occasionally supplementing their diet with small fish and squid. Pursuing prey on shallow dives, they use rows of interlocking upper and lower teeth to form a sieve-like palate which strains krill from the water. They can consume 20-25 times their body weight in a year. In fact, the total amount of krill consumed by Crabeater seals is more than that of all the remaining baleen whales put together.

Crabeater seals are more agile on land and ice than other Antarctic seals and thus can travel far from the open sea. The remains of dead seals, presumably trapped by pack ice, have been found miles from the sea.


During breeding season, Crabeaters are generally observed occurring in small family groups as opposed to the teeming breeding beaches of gregarious Fur seals. Not much is known about crabeaters' breeding, which occurs among the pack ice during the austral spring. Like Southern Elephant seal pups, Crabeater pups grow very quickly and are weaned within two to three weeks having gained up to 200 pounds in weight. During this period, the male patrols a sizeable territory (up to a 150 foot radius) around his mate and pup, aggressively fending off unwelcome intruders. Skirmishes are frequent with even the females becoming combative during this time. There is some evidence that Crabeaters may be monogamous, although this is rare in seals. After weaning, young Crabeater seals disperse to open waters to feed independently.

The Leopard seal is the main predator of young Crabeater seals and an important one in helping to keep populations in check.

 

  Did you know?


- Crabeater seals are now the single biggest consumers of krill, accounting for about 80 million tons a year.

- The crabeaters have remarkable five-pointed teeth, the upper and lower rows of which interlock to form a strainer, so they can retain the krill while allowing water to be expelled.

- When approached, crabeater seals do not roll onto their backs like Weddell seals; rather they open their mouths, bare their teeth, and snort.

- Crabeater seals can travel impressive distances on land. Dead seals have been found 35 miles up the Ferrar Glacier at almost 3,500 feet in elevation.