Weird Animal Question of the Week

How Do Some Animals Make Their Own Sunscreen?

Fish, hippopotamuses, and other animals produce chemicals that protect them from the sun's rays.

 

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Hippopotamuses (pictured, a Nile hippo at an Australian zoo) have skin pigments that protect them against sunburn.

 

On a recent beach trip I forgot to wear sunscreen and was left literally burning with regret.

But many wild animals, from fish to hippos, don’t have to remember to hit the drugstore to be protected from the sun’s powerful rays. (See "Mystery Solved: Why We Sunburn.")

To find out more, Saturday’s Weird Animal Question of the Week is taking author's prerogative to ask "Do animals make their own sunscreen?"

Sunscreen Gene

A recent study in the journal eLife found that some fish, birds, amphibians, and reptiles have the genes to produce gadusol, a compound that can act as a sunscreen.

"Gadusol absorbs UV radiation, particularly UVB [ultraviolet B], and dissipates it as heat," study leader Taifo Mahmud, a professor of medicinal chemistry at Oregon State University, says via email.

The gadusol produced by zebrafish, a highly studied lab species, may even help scientists create a better sunscreen for people. (Also see "Do Sunscreens' Tiny Particles Harm Ocean Life in Big Ways?")

By transferring the zebrafish genes into yeast in the lab, researchers were able to test gadusol’s activity as a sunscreen and show that it can be produced commercially.

So, can I just rub a zebrafish on my face next time I forget my sunscreen?

A bit impractical, says Mahmud, but cod and sea urchin eggs—popular sushi ingredients—can contain the radiation-absorbing chemical.

So "you may have consumed gadusol without knowing it," he says.

That doesn’t mean it will act as a sunscreen in you, however—so for now, follow experts' advice for sun protection.

No Sweat

Other animals devise or produce their own brand of SPF.

Hippopotamuses produce "sweat" made of one red and one orange pigment. A 2004 study in Nature revealed that the red pigment contains an antibiotic, while the orange absorbs UV rays. So the two pigments work together to protect the African mammals from both bacterial infections and sun damage. It also explains the misconception that they sweat blood. (Read how whales avoid sunburn.)

Mantis shrimp have amino acid pigments called MAAs in their eyes that are known as "nature's sunscreen," reports a 2014 study in the journal Current Biology. However in mantis shrimp, the pigments play another role: They serve as powerful filters that contribute to the crustacean's incredibly sharp and complex vision. (Related: "Nature's Most Amazing Eyes Just Got a Bit Weirder.")

Likewise, in zebrafish, gadusol may play multiple roles, including “some functions required to accomplish embryonic development,” says study co-author Robert Tanguay, professor of molecular toxicology at Oregon State University. The team is investigating those other possible roles.

West African lungfish don't make sunscreen, but they know how to stay cool: They bundle themselves in a cocoon of mucus before burrowing themselves into the mud during the dry season.

Snug and protected, the fish then go into a period of estivation, a period of dormancy some animals go into during the hot months, like a summer version of hibernation. (Watch a video of the West African lungfish.)

Wearing that sunblock doesn’t seem so bad now, does it?

Weird Animal Question of the Week answers your questions every Saturday. If you have a question about the weird and wild animal world, tweet me, leave me a note or photo in the comments below, or find me on Facebook.

 

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