Unfortunately, this hobby comes at a cost: the ordeal known as sunburn. And while the most likely victims of a sunburn are the lighter skinned – among us humans – animals are also at risk of sunburn.
If animals can also get sunburned, why don’t we see sunburned fish or pink elephants?
The truth is that, if we think about it, the sun has always been here in planetary terms , and all individuals have been exposed to it, so it is a fairly strong selective pressure towards animals, which has led to the development of various mechanisms to counteract it.
Adaptation
Some of these mechanisms are particularly obvious : the fur, wool, feathers, and scales of many creatures create a barrier between the sun and the skin. These adaptations are so effective that the only time they really fail is when humans intervene. For example, domesticated pigs, raised to have less hair, are more sensitive to sun damage than their wild cousins.
Animals with natural fur without hair and without scales must resort to other methods of self-protection. Elephants and rhinos don’t just have thicker skins; they are also regularly covered with dust or mud to create a rudimentary sunscreen. When conditions are extreme, most animals retreat into the shade or shelter in burrows, helping the animals cope.
Some species up the ante by producing a unique brand of sunscreen from their own cells. There are genetic traits in fish, birds, reptiles, and amphibians that allow them to produce a compound called gadusol , which creates protection against ultraviolet (UV) rays in the sun, something that most vertebrates have. So far, yes, they have shown that only zebrafish use this compound as a UV protector. But now scientists are investigating how humans could exploit this trait for our skin.
Why don’t we have this protection?
Why don’t we and other mammals produce gadusole? We don’t know, but it would be interesting to find out whether fur and thicker skin developed later in mammalian evolution.
Not to be left behind, gadusol-deprived mammals have developed their own sophisticated protection mechanisms. Hippos are known to secrete a scarlet fluid from their pores that resembles blood, and it wasn’t until 2004 that a group of Japanese scientists discovered that the orange-red compounds in this skin-coating fluid protected hippos. of UV rays, according to the study published in the journal Nature . Other animals focus their sun protection on the most vulnerable parts of their bodies. Giraffes, for example, produce more protective melanin on their tongues, giving them a darker hue, because they spend most of their lives with their tongues exposed to the sun while picking young leaves from trees for food.
So do they burn or not?
The answer is: Yes . Marine mammals, and specifically cetaceans such as whales or dolphins, are an exception because they do not have fur or scales. A 2013 study published in the journal Scientific Reports discovered signs of sunburn on the whales’ surface after hours spent breathing and socializing on the surface. But more importantly, they also discovered that whales have specialized mechanisms that help them counteract these burns.
No evidence of skin cancer in whales
Some whales generate pigments that darken and protect their skin; others have genes that trigger a protective stress response in the skin. There are even whales that have developed a hard, keratinized coat that protects the delicate skin underneath.
From protective coats, self-made sun creams, to quick healing, these animals may one day give us the clues we need to save our own skin.
Referencia: The red sweat of the hippopotamus. Nature May 2004. // Whales Use Distinct Strategies to Counteract Solar Ultraviolet Radiation. Laura M. Martinez-Levasseur, Mark A. Birch-Machin, Amy Bowman, Diane Gendron, Elizabeth Weatherhead, Robert J. Knell & Karina Acevedo-Whitehouse. Scientific Reports volume 3, Article number: 2386 (2013)
