The Mantis Shrimp

   I've always been fascinated by animals. Nature is a truly wondrous thing. And today, I'd like to introduce you all to one of the most incredible and mind-boggling creatures on the planet: the Mantis Shrimp.

Odontodactylus scyllarus, the Peacock Mantis Shrimp

   Mantis shrimps, despite the name, are not true shrimps at all, but a separate group of crustaceans called Stomatopods. These animals generally grow between six and twelve inches long, though some species can reach nearly eighteen inches, and are found in waters throughout the world. Despite its small size, this animal holds several World Records, including most advanced eyes, strongest exoskeleton, and fastest punch.

The Mantis Shrimp's eyes are without doubt the most advanced of any animal known. The human eye is equipped with three different types (red, green, and blue) of color-receptive cone cells. The Mantis Shrimp's eyes have sixteen different types. This allows them to see a range of light and color that no other animal on Earth is capable of comprehending, well into ultraviolet and infrared, turning their world into what must be an unimaginable storm of color. 

   Each eye also has three separate focal points as opposed to our one. This means that each eye takes three separate images of an object from a slightly different angle at the same time, giving the mantis shrimp unparalleled depth perception, and these eyes can swivel independently to take in a wrap-around view, or focus together for even better clarity. These eyes are so massive that the mantis shrimp has a highly-enlarged cluster of optic nerve endings that form a series of ganglia (basically micro-brains) to help it absorb all that data.

The eyes of a Peacock Mantis Shrimp, with a clear view of the three focal points

   If any of you are lost by this point, let me simplify. Every color you think you see is actually just a mixture of three different colors, and you can only see an object from two slightly-different angles at once (that's what gives you depth perception). So imagine if your eyes could see depth and distance three times better, and that you were capable of seeing more than five times the basic colors you can see now. For a human, the end result is a fried brain; we just can't handle that much raw data. So then add a cluster of tiny little mini-brains whose sole purpose is to control your eyes. Then you'd have the visual power of a mantis shrimp. Pretty insane. These eyes drive the mantis shrimp's second claim to fame; the fastest punch in the world. 

   Mantis shrimps come in two varieties; the first possess sharp, stabbing forelimbs which they use to impale softer-bodied prey, and are known as "spearers". These make up the majority of mantis shrimp species, and can strike prey in less than 0.025 seconds. 

A Zebra Mantis Shrimp (Lysiosquillina maculata) impales its prey

These species can strike very quickly, but the second variety of mantid shrimps are faster still. These variants possess shorter forelimbs which end in rounded, club-shaped tips with only small spines, and are known as "smashers". This group includes the Peacock Mantis Shrimp, Odontodactylus scyllatus, the most well-known species of stomatopod. Unlike their spearing cousins, smasher mantis shrimps target hard-bodied prey such as crabs, snails, and oysters, and they use one of the most terrifying weapons in nature to do so.

A Peacock Mantis Shrimp displays its smashing arms, prepped for action

   The arms of a smashing mantis shrimp are driven by a complex spring-action system of muscles and tendons. Once the smasher has locked on to its target, it darts out to deliver a strike of incredible speed and force. The strike itself is a rapid unfurling of the arms to drive the club-shaped tips towards prey at a speed of nearly 23 meters per second, roughly the same acceleration as a .22-caliber bullet fired from a rifle. The resulting impact force has been measured at 1500 newtons, powerful enough to crack an oyster and shatter aquarium glass up to a quarter-inch thick, but it was only recently that the true power of this blow was realized. 

A Peacock Mantis Shrimp demonstrates its punching technique on a snail

   The sheer speed of the movement forces water away from the arms, creating tiny vacuums known as cavitation bubbles. As soon as these bubbles form, the water pressure forces them to collapse, and they do so with such force that they produce a brief flash of light and a burst of heat of several thousand Kelvin. To put that in perspective, the surface of the Sun is about 5800 Kelvin, but the flash passes too quickly to be noticed without advanced equipment. The force of the collapse also produces a concussive shock wave against the surface of a target, so that the victim is struck twice; first by the arms, and immediately after by the cavitation blast. Even on the off chance that the mantis shrimp misses its target, the bubbles will still form and generate a shock wave capable of stunning or mortally wounding prey, giving the predator time to correct its aim for a second strike.

The end result of a Mantis Shrimp Boxing Match. Final score: Shrimp 1, Mussel screwed

   The idea of a simple crustacean attacking with such phenomenal force seems ludicrous, and it raises a very obvious question. With such incredible power, how does the mantis shrimp avoid harming itself? One would think that such a powerful blow would shatter its arms, but the Peacock Mantis Shrimp has been observed lobbing dozens of punches in rapid succession. The answer lies in the structure of its arms. In addition to an incredibly-thick layer of chitin (the material most crustacean shells are formed from), the surface of a mantis shrimp's clubs also contain layers of hydroxylapatite, a form of crystallized calcium that is stronger than any substance that mankind has yet to synthesize. This combination of minerals makes the arms incredibly resilient to fractures, and while the rigorous motion does wear the shell down over time, it is replenished and strengthened each time the mantis shrimp molts. This composition is so durable that scientists and engineers have begun researching it in the hopes of creating new materials for industrial use, and perhaps even advanced body armor.

A diagram of the cellular structure of a mantis shrimp club, next to a microscope image. Courtesy Kisalius Labs

A Peacock Mantis Shrimp, proudly displaying its punchy arms of death

    With such impressive weaponry and destructive potential, it is easy to label the mantis shrimp as a mindless, brutal killer, a sort of invertebrate psychopath. And its aggressive behavior certainly seems to reinforce this. Those who keep these creatures in captivity quickly learn that the mantis shrimp is not a community-friendly choice for aquaria, as it will readily attack any other denizens. But looks can be deceiving; the mantis shrimp is actually quite intelligent. Although they are territorial, individuals that take up burrows in close proximity to each other quickly learn to recognize their neighbors, and will behave less aggressively towards those that they are familiar with, though they will not tolerate interlopers. And there is a gentle side to this creature, one that makes itself clear in the reproductive cycle of several species. Mantid shrimps are among the only invertebrates that mate for life.

It isn't just the other tank-dwellers that are at risk from a captive mantis shrimp. This image beautifully details how they earned the nickname "thumb-splitter"

   A mantis shrimp can live for more than twenty years, and as soon as it reaches maturity, it begins seeking out a potential partner. While some species will take a new partner every year, there are others who, once they find a mate, will begin a true partnership. The two individuals, male and female, will share the same burrow together throughout the year, altering their patterns of behavior to better synchronize with one another. And when the time comes to breed, they work together to support both themselves and their offspring. In some of these pair-bonds, the male will take over hunting for the both of them, bringing enough food back to feed both himself and his mate. In others, he will actually share the burden of carrying the eggs, taking on half of their young himself. And in these species, the bond does not end with the close of the breeding season; the two will stay together for the rest of their lives, up to twenty years. While such monogamy is common in mammals and birds, it is virtually non-existent in invertebrates, and it is just one more amazing attribute that sets the mantis shrimp apart.

The Peacock Mantis Shrimp is one of several species that engage in monogamous pair-bonds. These two, caught in the act of breeding, will remain together for the remainder of their lives

   All in all, the mantis shrimp is truly a miracle of nature, and a wonder of the animal kingdom. It can see a range of color and light that no other living thing can comprehend. It strikes down its prey with punches too fast to see, and generates the energy of a star with each blow. It naturally grows a shell that is stronger than anything man has yet to achieve. And yet, for all its killing prowess, it possesses an intelligence greater than one would expect, a social life of surprising complexity and a capacity for partnership and loyalty that puts many humans nowadays to shame. Truly, the mantis shrimp is one of nature's most fascinating creatures, and yet another example of the incredible work of God.