"Fighting Family" "Color Master"? How come the mantis shrimp in your mouth can do everything?

Produced by: Science Popularization China

Author: Tian Dawei (popular science creator)

Producer: China Science Expo

The mantis shrimp we usually see are similar to the one in the picture below. But in fact, the family to which the mantis shrimp belongs is one of the best "fighting families" in the ocean, and it is also a "master of color". In this article, we will talk about the story of the mantis shrimp.

Mantis shrimp made into delicious food

(Image source: wikimedia)

Fierce cuisine

The mantis shrimp we often eat belongs to the mantis shrimp family . Mantis shrimp is also called mantis shrimp, and the reason for this name is related to the "weapon" they use to attack.

Next time you eat mantis shrimp, you can pull open the front claws of the steamed mantis shrimp and observe that its shape is particularly similar to the "scythe" of the mantis. Thanks to this "weapon", they have also become terrible killers in the ocean.

Mantis shrimp's "weapons"

(Image source: Reference [1])

The mantis shrimp will hide in a cave on the seabed. When a small fish approaches, the mantis shrimp will quickly rush out of the cave, pop out its "scythe" to pierce the small fish, and then drag it into the cave to enjoy.

Mantis shrimps are very fast when catching fish, and can complete an attack in about 20 milliseconds . In comparison, it takes about 200 milliseconds for a human to blink, so if you say that their attack is completed in the blink of an eye, it will be considered slow.

This terrible "weapon" can not only be used for hunting, but also can be used to defend itself with the "scythe" when facing danger (such as when being caught by people). Therefore, we must pay attention to safety when handling live mantis shrimp.

Wounds caused by mantis shrimp

(Image source: Reference [1])

In addition to the "scythe" of the mantis shrimp, the tail of the mantis shrimp we often eat also has sharp "barbs", so we must also be careful when handling it.

Mantis shrimp tail "barbs"

(Image source: Reference [1])

Ocean Boxer

In fact, members of the mantis shrimp family are divided into two categories. One category is like the mantis shrimp, which uses a "scythe" as a "weapon", and the other category uses a hammer as a "weapon ". The peacock mantis shrimp below is a typical representative of using a hammer as a "weapon".

The beautiful but not easy to mess with mantis shrimp

(Image source: wikimedia)

When this type of mantis shrimp attacks, it will press its fist against its chest. During this process, a special structure behind the mantis shrimp's fist will bend like a bow and accumulate energy. When the mantis shrimp gets close to its prey, it will suddenly release this energy and hit the prey with its fist at a speed of more than 80 kilometers per hour.

The mantis shrimp's fist can easily crush the shells of crabs and clams, and can even shatter the glass of the aquarium (so bulletproof glass is needed to keep mantis shrimp).

Mantis Shrimp Fist

(Image source: Reference [2])

Not only that, scientists have also discovered that when mantis shrimps attack their prey, the prey will receive multiple hits within one second .

This is not because mantis shrimps can throw several punches in one second, but because when they attack their prey, their high-speed fists collide with the prey's shell, creating a small vacuum area.

After the vacuum bubble is formed, the surrounding seawater will quickly squeeze in here, generating huge shock waves (even producing flames). These shock waves will cause secondary damage to the hard shell of the prey, helping the mantis shrimp to smash the shell of the prey.

But have you ever thought about this question? The food of mantis shrimp includes clams, conchs and other creatures with very hard shells, but why can the mantis shrimp's fists withstand repeated knocks without damage? Do mantis shrimps have their own "iron fists"?

Scientists are also curious about this question. After studying the fists of mantis shrimp, scientists found that although they do not have "iron fists", their special structure makes their fists extremely strong.

The "strike zone" of the fist is made mainly of chitin and hydroxyapatite . Chitin is very common in the exoskeletons of crabs and shrimps, and hydroxyapatite is similar to the material on the surface of our teeth. So the mantis shrimp's fist is not made of any rare substances. But the arrangement of these substances is very interesting. They overlap with each other and form a structure similar to the DNA helix.

The arrangement of materials in a mantis shrimp's fist

(Image source: Reference [3])

This structure allows the mantis shrimp to distribute force throughout its fist when attacking, thus preventing the fist from breaking.

Based on this structure, scientists are also developing similar biosynthetic materials, which may be used in the future to make new bulletproof vests, or be used in the medical and construction fields to create light and strong materials.

"Color Master"? The controversial world of color

In addition to the mantis shrimp's fist, another skill of the mantis shrimp also shocked scientists, and that is its superb visual system .

We humans can recognize a variety of colors because there are three types of cone cells in our eyes, which are sensitive to yellow-green, green, and blue-violet light. The light signals they receive converge in the brain, and we have a colorful world.

The light-sensitive areas of different types of cones

(Image source: wikimedia)

In contrast, some birds have four types of cones, allowing them to see more colors, including ultraviolet.

In mantis shrimp's eyes, there are more than 10 types of photoreceptors , leading some scientists to speculate that they can see more colors.

But other scientists believe that the world seen by mantis shrimp is not as colorful as we imagine. This is because, although there are many types of photoreceptors in their eyes, their brains may process visual signals very differently from our brains. Therefore, there are still many secrets to be discovered about the vision of mantis shrimp.

But one thing is certain, that is, mantis shrimp can see polarized light that humans cannot see , which can help mantis shrimp identify prey more clearly in the marine environment.

The mantis shrimp's delicate eyes

(Image source: wikimedia)

Scientists have created a very low-cost polarized light camera based on the structure of mantis shrimp eyes. Such a camera can help doctors see lesions more clearly and save patients' lives; self-driving cars can also "see" more clearly in rainy and foggy days; military drones can also use it to more clearly identify camouflage and find enemies.

I didn't expect that mantis shrimp, a delicacy on the table, has so many aspects worth studying. Will you enjoy it more next time you eat mantis shrimp? (Well, no)

Conclusion

Delicious food on the table, fierce killer in the ocean, master of color in vision, these are the labels of mantis shrimp. This seemingly ordinary creature in the ocean has so many amazing things hidden in it.

What other shining points of mantis shrimp have not been discovered yet? What other biological treasures are there in the ocean? Let's look forward to it together!

References:

[1] Amaral ALS, Castilho AL, Haddad Junior V. Injuries in humans caused by mantis shrimp or siriboia (Crustacea: Stomatopoda)[J]. Revista da Sociedade Brasileira de Medicina Tropical, 2021, 54.

[2] Tadayon M, Amini S, Wang Z, et al. Biomechanical design of the mantis shrimp saddle: a biomineralized spring used for rapid raptorial strikes[J]. IScience, 2018, 8: 271-282.

[3] Thomas Cronin. Why Mantis Shrimps, Not Sharks, Might Be the Most Amazing Predators in the Sea

[4] James C. Weaver et al. ,The Stomatopod Dactyl Club: A Formidable Damage-Tolerant Biological Hammer.Science336,1275-1280(2012).

[5] Morrison, J. Mantis shrimp's super color vision debunked. Nature (2014).

[6] Prachi Patel. Camera Mimics Mantis Shrimp's Astounding Vision.