Crabeater and Weddell seals live abundantly in the southern oceans. Both species are incredibly admirable for being well adapted to living around Antarctica, a tough environment to call home.

These seal species don’t compete for living space or food because each has its own niche. Crabeaters rest on individual ice floes floating on the ocean around Antarctica. But Weddells lie on vast stretches of fast ice, which is closer, and attached to, the Antarctic continent.

With about 75 million individuals, crabeaters are the most abundant seals in Antarctica and the most common large mammals in the world, after humans. And crabeaters owe their abundance to ingesting trillions of krill, a kind of small, shrimplike crustacean.

Algae grow by the many tons in sunlight under the sea ice. Krill consume much of those algae, and crabeater seals eat those little crustaceans by the tons. With their mouths wide open, crabeaters swim into huge swarms of krill. The seals’ serrated teeth filter krill from ocean water.  

Crabeaters are chunky with fat to stay warm and have pale-gray hair. They can live up to 40 years.

Crabeaters mate from September to November, the Antarctic spring. Each female has one pup per year, which nurses from her for about three weeks. Each youngster weighs about 40 pounds at birth, but is, amazingly, around 240 pounds in three weeks. Crabeaters’ milk is rich in fat and protein, causing such fast growth.         

With around 800,000 individuals, Weddell seals are the second most abundant seal species around Antarctica. They are also chunky to retain heat, have dappled-gray hair, and can weigh up to 900 pounds, on average, when mature. They also have small heads and flippers to retain body heat.

Weddell seals can live up to 25 years and are the southernmost breeding mammal in the world. They can dive down 2,000 feet to catch fish, squid, octopus, and crustaceans and hold their breath for close to an hour.

In winter, Weddells live in the ocean under the fast ice. They use their strong, sharp teeth to create and maintain breathing holes in the ice. But that ice chewing wears down their teeth to the point that they can’t catch prey animals. Weddells need to evolve even stronger, sharper teeth.     

Leopard seals and killer whales prey on crabeaters and Weddell seals. The whales sometimes knock their potential victims off the ice and into the ocean, where they can grab them. 

Crabeater and Weddell seals are tough, adaptable creatures that flourish in an uncompromising environment. I have to admire their adjustments and endurance in their respective niches. But then, all nature is admirable. 


Clyde McMillan-Gamber is a retired Lancaster County Parks naturalist.

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