[INTRO].

Mantis shrimp have lots of  striking characteristics. They have big, rainbow-colored  bodies and they punch so strong it can break glass.

But one of their more discreet superpowers  is the ability to see polarized light. This might not seem like a huge deal. Except that cancer cells interact  with polarized light in a unique way.

So researchers are developing  cameras that can see like mantis shrimp see, and detect  very early stages of cancer. Compared to humans, mantis shrimp  have incredibly advanced eyesight that allows them to very accurately  scan for prey or potential threats. To start, they have compound  eyes, similar to those of a fly.

Each eye is divided into three sections  that the shrimp can move independently. And while humans have three different color  receptors, mantis shrimp have sixteen. Plus, they have six receptors capable of  picking up different kinds of polarized light.

Now, most light sources we encounter,  like the sun and light bulbs, emit unpolarized light. Unpolarized light is... messy. It’s made of multiple waves that  vibrate in multiple directions, technically planes, at the same time.

But there are a few different ways  for light to become polarized, where light waves are vibrating in only one plane. Reflecting off surfaces, for example,  or passing through something, like polarized sunglasses. And mantis shrimp eyes can detect polarized light.

Researchers believe mantis shrimp  evolved this ability for hunting. When light gets reflected off an  animal, like a fish with shiny scales, some of it becomes polarized. So, thanks to their unique eyesight,  mantis shrimp can accurately spot their unsuspecting prey underwater.

Mantis shrimp can even perceive  circular polarized light, a hard-to-see light wave that rotates its plane of polarization in a clockwise  or counterclockwise direction. Mantis shrimp use circular polarized  light to communicate within their species. Their bodies have reflective surfaces capable of producing this kind of light, which  they flash like a secret message.   Now human eyes can detect some polarized light, but not nearly to the same  extent as mantis shrimp.

And we can’t distinguish  circular polarized light at all. That’s partly because mantis  shrimp eyes have more receptors. Plus, all the shrimp's photosensitive  bits are stacked on top of each other, and their polarization receptors are  oriented in different directions.

This makes it possible for the shrimp  to intercept light waves coming from multiple directions at the same time and helps them perceive changes in polarization. Researchers believe these  shrimp can even rotate the different sections of their eyes to  maximize their detection of polarized light. Similar to a person like putting on  polarized sunglasses to filter a glare.

Polarized sunglasses can block light  waves vibrating in one direction, while allowing light waves vibrating  in another direction to pass through. So where does cancer diagnosis fit into  this already really remarkable story? Could we put a mantis shrimp  on someone with cancer and have it punch them in the tumor?

No… as cool as that would be. But in their 2017 paper in the journal Optica, researchers from the University of  Illinois say they were inspired by the mantis shrimp’s sophisticated  eyesight to develop a camera capable of detecting cancer  cells very early in their development. In particular, they drew inspiration  from the shrimp’s stacked photoreceptors.

In their camera, the researchers stacked multiple silicon photodiodes on top of each other. They combined this with a  carefully arranged pattern of metallic nanowires to  act as polarization filters. This allows the camera to see  in color and detect polarized light coming from different directions,  much like the mantis shrimp.

And that’s key to identifying cancer in its  early stages because when researchers aim polarized light at tissues in the body,  the light is scattered by the cells. And they’ve found that healthy cells  all scatter this light in a similar way. But cancerous cells do not.

That’s partly because fast-growing  cancer cells are oddly shaped and irregularly spaced in  comparison to healthy tissue. They can also have multiple nucleii  and be denser than a healthy cell. In 2013, researchers studying colorectal  cancer proposed that cancer cells can even change the direction  of circular polarized light.

And the degree to which they  change this light’s direction depends on how aggressive that cancer is. This impact on polarized  light shows up very early on, prior to the onset of symptoms or changes  that are visible to the human eye. So a camera capable of viewing multiple  types of polarized light would be an extremely useful tool for early cancer  detection, especially during procedures that require a miniature camera,  like a colonoscopy, for example.

During this type of procedure,  a doctor uses a small camera to spot tissues that look  different from healthy tissue. This means the cancer has to  be fairly advanced for our feeble eyesight to notice a difference. But the shrimp-inspired camera could improve  cancer detection rates during these procedures.

In fact, early prototypes  used on mice have successfully revealed where healthy tissue  ended and cancerous tissue began. If doctors can use these cameras  to find tumors much earlier on, they can use less invasive treatments  and decrease recovery times. As an added bonus, this camera is smaller, lighter and less expensive  than existing technologies.

Which means it could be really  useful in resource-limited locations. So one day, these cameras could become  a part of your doctor’s toolkit, bringing the superpower of a mantis  shrimp's eye to your very colon. Thank you for watching this episode of SciShow!

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