Mantis Shrimp Uses 'Biological Sunscreen' to See

Mantis shrimps have complex eyes that generate ultraviolet color vision, a new study states.

Human eyes have three color receptors, while the mantis shrimp eyes have as many as 12 such receptors, according to the National Geographic.

Researchers at the University of Maryland Baltimore County found that at least six UV photoreceptors in mantis shrimp use "biological sunscreens" to detect colors that fall within the UV spectrum. The biological sunscreen, which is used by other creatures to prevent damage from UV rays acts as a filter in mantis shrimps' eyes.

"The mantis shrimp visual system contains six types of photoreceptors functioning completely outside the visual range of humans," said Michael Bok of the University of Maryland Baltimore County, according to a news release. "Surprisingly, they produce their six UV photoreceptors using only two types of visual pigments by pairing one visual pigment with one of four UV filters. The UV filters block certain wavelengths of light from reaching the photoreceptors, chromatically shifting their sensitivity."

The filters in mantis shrimp have mycosporine-like amino acids (or MAAs), which are often found in the skin of other marine organisms.

"The effect is akin to putting red-tinted glasses over your eyes that block other wavelengths of light, except this is being done at the photoreceptor cellular level in shrimp," Bok explained.

Researchers aren't sure why mantis shrimps have such complicated vision. One reason could be that these creatures live in vibrant reefs and so need complex visual tool to hunt prey. Another reason could be that the UV light detecting ability helps the organism pick up social cues.

Interestingly, mantis shrimp doesn't have a big brain to process information coming from all the "extra" photoreceptors, meaning that the creature doesn't have to "think" about the visual inputs. Researchers said that the vision system in the mantis shrimp is so complex that humans could never conceptualize how the creature perceives the world.

The study is published in the journal Current Biology.