Mantis Shrimp Have Perfected the Eye Roll to Better See Things We Can't Even Imagine

Mantis Shrimp Eyes
Mantis shrimp have a punch strong enough to break glass, boil water and kill each other. Michael Bok/University of Lund

The bizarre and violent mantis shrimp has many awestruck fans on land. Part of the appeal is its ridiculous strength and creative hunting technique: Its club-like claws accelerate at the speed of a .22-caliber bullet, enough to dismember crabs and other prey. But if the shrimp misses its target, it likely wins anyway: Its powerful punch essentially boils the surrounding water into vapor bubbles. The bubbles create heat, light and a forceful sound when they implode and collapse. That usually finishes the job.

On the less gruesome side, mantis shrimp have some of the most remarkably advanced eyes on the planet. Humans eyes have three types of color receptors that allow us to see a full spectrum of colors. But mantis shrimp eyes have 12 of these receptors, meaning they see colors beyond our wildest dreams.

But as of this week, scientists have another reason to gawk at mantis shrimp eyes: In a paper published Tuesday in the journal Nature Communications, researchers described how mantis shrimp roll their eyes—sometimes separately—to improve their ability to see. It's a skill unlike just about every other animal on Earth.

"We have known for a while that mantis shrimp see the world very differently from humans," Nicholas Roberts, an optical mechanics researcher at the University of Bristol and author on the study said in a statement. "Intuitively, a stable eye should see the world better than a mobile one, but mantis shrimp seem to have found a different way to see more clearly."

The feature is almost unique among animals, according to the paper, and "each eye may also move largely independently of the other." Mantis shrimp are able to see the polarization of light. They see with, presumably, far less glare and distortion, and the eye roll is key in "maximizing the polarization contrast between an object of interest and its background," the researchers write. "This is the first documented example of any animal displaying dynamic polarization vision, in which the polarization information is actively maximized through rotational eye movements."

According to the researchers, understanding these mechanics could "prove useful for developing bio-inspired technology in the field of polarization cameras and image processing," helping make cameras that more effectively manage glare and color-distortion issues.

And if researchers can figure out how the mantis shrimp manages to process two separate streams of visual information from its two separately rolling eyes—something the researchers point to as a major, unanswered question—that might lead to new, high-performance sight systems for underwater robots.