Why Do Whales Migrate? It's Skin Care

by GoNews Desk 5 months ago Views 1919
Whales, at the top of the food chain in the marine environment, undertake some of the longest migrations on earth, often swimming many thousands of miles, over many months, to breed in the tropics. This ritual of the oceans' largest mammal had intrigued scientists for years. Now scientists have proposed that whales that forage in polar waters migrate to low latitudes to maintain healthy skin. 

"I think people have not given skin molt due consideration when it comes to whales, but it is an important physiological need that could be met by migrating to warmer waters," said Robert Pitman, lead author of the new paper - Skin in the game: Epidermal molt as a driver of long‐distance migration in whales, and marine ecologist with Oregon State University's Marine Mammal Institute.

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All birds and mammals regularly shed their skin, fur, or feathers in a process known as molting. Pitman and his co-authors propose that whales foraging in the freezing waters of Antarctica conserve body heat by diverting blood flow away from their skin. That would reduce the regeneration of skin cells and halt the normal sloughing of skin.

Over eight years, scientists deployed 62 satellite tags on killer whales. They found that all four types that feed in frigid Antarctic waters migrated as far as 11,000 kilometers (almost 7,000 miles) round trip. Most migrations were fast, non-stop, and largely straight north and back. One whale completed two such migrations in 5.5 months. Researchers also photographed newborn killer whale calves in Antarctica, indicating the whales don't need to migrate to warmer waters to give birth as previously established by whalers. 

Migrating to warmer water would allow whales to revive their skin metabolism and molt in an environment that does not sap their body heat. The authors suggest that this drives their migrations. Coauthors on the paper include scientists from NOAA Fisheries; SeaLife Response, Rehabilitation, and Research; and the Italian National Institute for Environmental Protection and Research.


Courtesy: Robert L. Pitman, John W. Durban, Trevor Joyce, Holly Fearnbach, Simone Panigada, Giancarlo Lauriano. Skin in the game: Epidermal molt as a driver of long‐distance migration in whalesMarine Mammal Science, 2019; DOI: 10.1111/mms.12661


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