Whales get a tan too!

Whales show increase in their skin pigment in response to sunshine and get a 'tan' just like humans, scientists have found.

Some species of whales get darker with sun exposure, incurring DNA damage in their skin and just like humans, they also accumulate damage to the cells in the skin as they get older, researchers said.

Experts from Newcastle University, UK were called in after marine biologists in Mexico noticed an increasing number of whales in the area had blistered skin.

Analysing samples from three types of whales - blue, sperm and fin - they worked together to study the changes in the whale skin after their annual migration to sunnier climes.

Over three years, the team of marine biologists from Trent University, Canada and Universities in La Paz and Queretaro, Mexico, took skin samples from the backs of three species of whales during their annual migration.

Occurring between February and April the whales move to the sunnier Gulf of California, along the northwest coast of Mexico.

Blue whales, the jumbo-jet sized giants, have a very pale pigmentation. During migration time the team found a seasonal change with the pigment in their skin increasing as well as mitochondrial DNA damage.

This internal damage to the mitochondria, the engines of the cells, is caused by UV exposure and is what is found in sunburned human skin.

Sperm whales with their distinctive rounded foreheads have a darker pigmentation, also migrate between February and April to the Gulf of California, but have a different lifestyle. They spend long periods at the surface between feeds and are therefore, exposed to more sun and UV.

The scientists found the sperm whales had a different mechanism for protecting themselves from the sun, triggering a stress response in their genes.

"We saw for the first time evidence of genotoxic pathways being activated in the cells of the whales - this is similar to the damage response caused by free radicals in human skin which is our protective mechanism against sun damage," said Amy Bowman, a Newcastle University researcher.

In contrast, the darkest whales, the deeply pigmented fin whales, were found to be resistant to sun damage showing the lowest prevalence of sunburn lesions in their skin.

"We need to investigate further what is happening, if we are already seeing blistered skin in the whales caused by UV damage then we want to know whether this could develop into skin cancer and therefore serve as an early warning system," said Mark Birch-Machin, Professor of Molecular Dermatology at Newcastle University and joint senior author of the paper.

The research was published in the journal Scientific Reports.