How Do Whales Avoid Sunburn?

Blue, fin, and sperm whales have different strategies to avoid sun damage.

Species like Sperm whales can spend up to six hours at the ocean's surface in between dives, baking in the sunlight. So how do they protect themselves from a serious case of sunburn?
It turns out that their bodies have similar defense mechanisms against the sun's ultraviolet (UV) radiation as people, according to a new study published August 30 in the journal Scientific Reports.

Researchers took more than a hundred skin biopsies from blue, fin, and sperm whales in the Gulf of California (map) from 2007 to 2009. They used crossbows loaded with modified arrowheads to retrieve plugs of skin from the marine mammals.

They found that Blue whales—which have the lightest skin color of the three species—tanned during their summer sojourns before migrating back to their northern feeding grounds.

Sperm whales didn't tan. Instead, the whales, which can receive an "overdose" of UV radiation during their hours at the ocean's surface, have proteins that protect their cells from UV damage, said study co-author Mark Birch-Machin, a professor of molecular dermatology at Newcastle University in the United Kingdom.

This process is similar to how human bodies produce antioxidants in response to free radicals, molecules that can cause a lot of genetic and cellular damage.

And Fin whales escaped sun damage thanks to their high levels of melanin—a skin pigment also shown to protect humans from UV radiation.

Uncharted Territory
Studying how whales react to UV-radiation damage has never been done before, making the new paper very useful, said Marie-Francoise Van Bressem, a veterinarian specializing in skin diseases in whales, dolphins, and porpoises at the Peruvian Centre for Cetacean Research in Lima.
Images: • Sperm whales (tail flukes pictured) must contend with getting too much sun, as they can spend hours at the ocean's surface.

• Sperm whales' heads are filled with a mysterious substance called spermaceti. Scientists have yet to understand its function, but believe it may help the animal regulate its buoyancy. 

• Earth's largest animal, the endangered Blue whale can eat some 4 to 8 tons (3.6 to 7.3 metric tons) of krill per day. 

• Fin Whale (Balaenoptera physalus)