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Brainy Baby Seals

June 5, 2013

Weddell seal pups survive infancy with the help of surprisingly large brains.



Little seals with big heads. I’m Bob Hirshon and this is Science Update.

Life is tough for newborn Weddell seals. They have just six weeks to learn how to hunt beneath Antarctic sea ice before their mothers leave them to fend for themselves.

REGINA EISERT (Smithsonian Institution/University of Canterbury):

Most marine mammals will not enter closed ice because they are afraid of drowning. Basically if you don’t find your exit, you’re dead.


That’s comparative physiologist Regina Eisert of the Smithsonian Institution and the University of Canterbury in New Zealand. She and her colleagues have now discovered the key to the baby seals’ rapid learning: big brains.


The newborn Weddell pup has a brain that is around 70% of the adult brain. The largest brain of any mammal studied to date relative to its adult size.


She says in contrast, the brains of human babies are only about 25% of their adult size. I’m Bob Hirshon, for AAAS, the science society. 

A 5-week-old Weddell seal pup and its mother on sea ice in McMurdo Sound, Antarctica. By around 6 weeks of age, the pup will have to hunt for itself under closed sea ice. (Regina Eisert)