Mantis shrimp posses optics that generate ultraviolet (UV) color vision.
The animals' six UV photoreceptors pick up different colors within the UV spectrum using spectrum based filters most animals rely on as "biological sunscreen," Cell Press reported.
The findings were published in the July 3 issue of Current Biology.
"The mantis shrimp visual system contains six types of photoreceptors functioning completely outside the visual range of humans," Michael Bok of the University of Maryland Baltimore County, said. "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 are made up of mycosporine-like amino acids, which are often found in the skin of marine microorganisms and work to absorb UV rays.
"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 are still unsure as to why mantis shrimp need such sophisticated visual systems. Mantis shrimp use visual cues to spot prey and evade predators. These creatures also have complex social interactions that are believed to be mediated by visual signals and body language.
Their complex eyes, which contain 16 or more photoreceptors could provide them with "complex color and polarization visual system without a big brain to post-process lots of information." This means their eyes could respond to complex visual inputs without needing to think about it very hard.
"The way their eyes are built and how visual information is processed in their brains is so fundamentally different [from] humans that is very difficult to conceptualize what the world actually looks like to them," Bok said.
