People see a beautiful world of colors, but what do other animals see? Some animals see a lot more than we do, but no one really knows how they use this sight.
We see what we see because our eyes have three photoreceptors, red, green and blue. The eyes of dogs only have two photoreceptors, which are green and blue. But the eyes of many birds have four photoreceptors, which are red, green, blue, and ultraviolet (UV).
It is difficult to imagine adding a UV photoreceptor, and it is even harder to imagine how invertebrates see. Butterfly eyes have five photoreceptors that let them see in ultraviolet light and help them tell the difference between two colors that look a lot alike.
Octopuses do not have colour vision but they can detect polarised light. We know that light is made up of waves when all of these waves move in the same plane. The closest humans come to seeing polarised light is by wearing polarised sunglasses.
But this is not the end of the story. Mantis shrimp vision puts everything else to shame. These marine crustaceans may be well-known for their record breaking punch (the same acceleration as a . 22 calibre bullet), but they also hold the world record for the most complex visual system.
They have up to 16 photoreceptors and can see UV, visible and polarised light. In fact, they are the only animals that can detect circularly polarized light. This is when the wave part of the light moves in a circle. They also can perceive depth with one eye and move each eye independently. Its impossible to imagine what mantis shrimp see, but incredible to think about.
Like flies, mantis shrimp have compound eyes with tens of thousands of ommatidia, which are parts that hold a group of photoreceptor cells, support cells, and pigment cells. Gonodactylids and Lysiosquillids are species with great eyesight. In the middle of their eyes, there are six rows of modified ommatidia known as the mid-band. This is where the magic happens.
Each row is specialised to detect either certain wavelengths of light or polarised light. The first four rows detect human visible light and UV light. In fact, each row contains a different receptor in the UV, giving mantis shrimp extremely good UV vision.
The ommatidia of the last two rows contain very precisely positioned, tiny hairs. This arrangement is most likely responsible for their polarisation vision.
The overall structure of the eye is intriguing too. Three parts of each eye look at the same point in space. This makes about 20% of the eye focus on a narrow strip in space and also lets them see depth with just one eye.
To create an using this strip, mantis shrimp are constantly moving their eyes and scanning the environment. The fact that the mantis shrimp can move each eye separately is helpful here because it gives it a wide field of view.
Mantis shrimps have perhaps the most complex and remarkable vision in the animal kingdom. Their eyes put human eyes to shame with the ability to see colors, polarization, and details that are invisible to us. In this article, we’ll take a deep dive into the mantis shrimp’s incredible visual capabilities and recent discoveries into how their brains process all this visual information.
A Massive Variety of Photoreceptors
The key to the mantis shrimp’s astounding vision starts with their eyes. Their compound eyes contain 16 different types of photoreceptors, the light-sensing cells in animal eyes. Humans only have 4 types. This allows mantis shrimp to see an incredible variety of light.
They can see ultraviolet and polarized light in addition to normal visible light. Polarized light waves vibrate in a single direction. We can’t see it, but mantis shrimp have 6 different photoreceptors just for detecting different directions of polarized light. Their massive variety of photoreceptors allows them to essentially see millions more colors than we can perceive.
Seeing Cancer and Secret Communication
Researchers are still discovering potential uses for the mantis shrimp’s extensive visual capabilities. Some believe they may use ultraviolet signals to communicate with each other in secret shrimp language that other species can’t detect. Their ability to see polarized light could let them spot predators swimming above them that are invisible to other fish.
Remarkably, mantis shrimp can even detect certain types of cancer in other sea creatures. Their sensitivity to polarized light allows them to see the tiny changes in tissues that indicate diseases like cancer. This has inspired researchers to develop new cancer-detecting cameras based on the mantis shrimp eye.
Trinocular 3D Vision
Most creatures, including humans, use two eyes to see the world in 3D. Mantis shrimp take it up a notch with a triple eye setup. Each eye moves independently on an eye stalk. The eyes can rotate and point in different directions.
Even more incredibly each individual eye contains depth perception on its own. So a mantis shrimp sees three overlapping fields of 3D vision giving it unparalleled spatial awareness. Their vision covers nearly 360 degrees around them.
Tiny Brain, Huge Visual Processing Power
The mantis shrimp brain is only the size of a finger. Yet it somehow processes all the visual information from their superpowered eyes and makes sense of their incredibly complex visual world This has presented a mystery – how does their tiny brain handle so much visual data?
Recent research has mapped the mantis shrimp’s visual system to identify how different parts of their brain work together to translate their remarkable vision into understanding. Key areas called the lobula and mushroom body appear crucial. The lobula converts raw visual input into recognizable shapes and objects. The mushroom body handles learning and memories and connects with the lobula to attach visual information to past experiences.
This understanding of how mantis shrimp brains function could provide insight into visual processing that could inspire advancements in computer vision and artificial intelligence.
What Does a Mantis Shrimp Actually See?
So what does the world actually look like through the eyes of a mantis shrimp? For them, the underwater world must be incredibly rich with colorful details, secret signals, and visual information that we are oblivious to.
Researchers have developed special cameras that mimic some aspects of mantis shrimp vision to get a glimpse. These cameras reveal a world saturated with polarized light invisible to us. Background polarization fluctuates unlike anything marine biologists expected. This is likely full of navigational information for mantis shrimp and other species that detect polarization.
While fascinating, these cameras still can’t replicate anywhere close to the full scope of mantis shrimp vision. Much remains mysterious about exactly how they perceive the world with their remarkably complex visual system. As researchers continue studying these incredible animals, we keep learning just how superior their vision is to our own. The mantis shrimp sees a world that most of us will never experience firsthand.
I see … but what’s it for?
Many animals are known to use visual signals. Female peahens like male peacocks with more eye spots in their train, and male chameleons show they are in charge by using brighter colors. Behavioural observations and morphology suggest that mantis shrimp are using their complex visual system for communication, too.
Male mantis shrimp are known to perform courtship dances to females and aggressive displays to other males. Both behaviours show off coloured patches which vary in reflectance properties (e. g. brightness, colour) across individual mantis shrimp. This suggests that flashing these patches could provide information to the receiver about the signaller.
Despite these indications that mantis shrimp are using visual signals, the work on this topic is sparse. Circularly polarized light may be used by mantis shrimp as a way to communicate secretly and for courtship. Besides this, we know very little about visual communication in mantis shrimp.
What does the mantis shrimp see?
How do mantis shrimp see?
The first four rows detect human visible light and UV light. In fact, each row contains a different receptor in the UV, giving mantis shrimp extremely good UV vision. The ommatidia of the last two rows contain very precisely positioned, tiny hairs. This arrangement is most likely responsible for their polarisation vision.
Do mantis shrimp have eyes?
Mantis shrimp have unusual eyes. Mostly famously, they have 16 color receptors, compared to a human’s three. Oddly, they are not that good at distinguishing between colors, but they can detect another property of light invisible to humans: polarization.
How many colors can mantis shrimp see?
Mantis shrimp can also see a wider range of the spectrum—from ultraviolet to infrared—and in more colors than humans can. Where we see three colors (red, yellow, and blue, combining them in different proportions to see green, orange, purple, and the rest), mantis shrimp can see between 12 and 16 colors, depending on the species.
Why do mantis shrimp have different colours?
The brain compares the information from each type of receptor to come up with yellow. Using this system, the human eye can distinguish between millions of different colours. Mantis shrimp are fierce predators.