The Mantis Shrimp: Supervillain of the Sea

These amazing creatures, also known as stomatopods, dwell in shallow near-shore marine environments. Most are around 15 cm in size, though some can grow up to 40 cm long, which is longer than my forearm. They aren’t true shrimp (which are classified in Order Decapoda, not Stomatopoda), though both are crustaceans within Class Malacostraca. Mantis shrimp possess some unique abilities, which are sharpened by their violent, aggressive temperaments, making them the crustacean supervillains of the oceans.


“Odontodactylus Scyllarus 2” by Roy L. Caldwell, Department of Integrative Biology, University of California, Berkeley, via Wikimedia Commons

So what are their superpowers?

  • Amazing Vision. Animals perceive color by absorbing various wavelengths of light with color photoreceptors, each type absorbing best at specific wavelengths. In humans, the “blue,” “green,” and “red” photoreceptors (which actually have peak absorptions in the blue, green, and yellow ranges, respectively) allow us to see colors ranging from red to violet. Most birds have a fourth type of color photoreceptor that is sensitive to UV wavelengths, allowing birds to see ultraviolet as a color.

    Mantis shrimp? They have up to sixteen types of photoreceptors. Twelve of them are for color.

    Four of these photoreceptors are for ultraviolet alone, and mantis shrimp color vision ranges from red to ultraviolet. But this incredible level of color detail, which allows them to see hues we humans cannot even imagine, is not the only amazing thing about mantis shrimp vision.

    Mantis shrimp can “tune” their vision based on environmental light conditions. Underwater, longer wavelength light tends to fade away faster than shorter wavelength light. This means that in very shallow water, the full spectrum of light is visible, but in deeper water, the environment is composed of shades of blue, violet, and ultraviolet. Mantis shrimp have color filters in their eyes that allow them to adjust to changes in the wavelength composition of their environment.


    “Mantis shrimp near Nusa Kode Island,” by Alexander Vasenin, via Wikimedia Commons

    Each eye is divided into two hemispheres, with an “equator” of six lines of ommatidia. Each line analyzes a different aspect of incoming visual information. The visual fields of the top and bottom sections of each eye overlap to some degree, allowing the mantis shrimp to have stereoscopic vision within a single eye, which is useful, since the two eyes move independently of each other. Mantis shrimp vision is so complex that different sections of the mantis shrimp’s compound eyes are allotted separate tasks. Using one part of the eye, a mantis shrimp might observe the color of an object; using another part, it might analyze the polarization of incoming light. Our own visual system cannot detect the polarization of light, but mantis shrimp can glean useful information about the orientation and texture of objects that reflect and scatter light in various directions.

    If their vision is so complicated, you might ask, how do mantis shrimp process all of the information, given the small size of their brains? As it happens, mantis shrimp employ parallel processing within the retina itself, meaning that much of their visual intake is processed before it even reaches their brain.

  • Mantis shrimp vision enables them to see in ultraviolet, to perceive fantastic color detail, and to detect polarized light – an impressive array of abilities. What other powers do they have in their arsenal?

  • Incredible Punch. As predators, mantis shrimp pursue one of two strategies of attack: spearing and smashing. Many species of mantis shrimp are “spearers,” killing their prey (and, frequently, each other) by stabbing with specialized sharp limbs. As impressive as this is, I find the “smashers” even more amazing.

    For an example of a “smasher,” let’s look at the peacock mantis shrimp, Odontodactylus scyllarus*:


    “Odontodactylus Scyllarus” by Silke Baron, via Wikimedia Commons

    The peacock mantis shrimp has a pair of reinforced, club-shaped limbs specialized for punching, rather like a pair of boxing gloves permanently attached to their bodies. The mantis shrimp prepares for a punch by locking the club in place with a spring-and-latch mechanism, then building up tension against the latch by contracting a muscle, before releasing the latch all at once. The club shoots forward at speeds up to 23 meters per second (that’s about the speed of a running cheetah) and punches the mantis shrimp’s prey with a force of up to 1500 Newtons. The punch only takes a few milliseconds, and the acceleration of the club can equal that of a .22 caliber bullet.

    Such a punch can be devastating, even to strong materials like a clam’s shell, but the attack isn’t over yet. The club punches through the water so fast that surrounding water vaporizes in a process called cavitation, creating a pocket of empty air in the wake of the punch. This space doesn’t stay empty for long. The surrounding water collapses back in on the space and crashes into the mantis shrimp’s prey in a second onslaught, often even more powerful than the first.

    A “smasher” mantis shrimp doesn’t let up the beating until its prey – a crab, a snail, a clam, or even a fellow mantis shrimp – shatters. Their punches are so powerful they can even crack aquarium glass, which make them a fearsome enemy indeed.

  • Body Armor. “Smasher” mantis shrimp can repeatedly pound away at their enemies with enough force to shatter shells, yet they only need to replace their clubs with the occasional molt. How can this be?

    It turns out that the molecular makeup of mantis shrimp exoskeletons – particularly of their clubs – is exceptional. On a micro scale, the structure of the club is extraordinarily resistant to fracture and damage, yet retains its hardness and effectiveness as a weapon. The mantis shrimp’s stiff telson – the hindmost segment of the exoskeleton – also excels at dissipating violent impacts, which mantis shrimp encounter during their frequent bouts of violence against one another.

    Like the resilient, resourceful villains they are, mantis shrimp employ reinforced armor both as protection and as a weapon.

  • Captivating Beauty. On top of these abilities, many mantis shrimp are simply breathtaking to look at – after all, every worthwhile villain needs a good sense of style. A picture will tell more than words alone, so feast your eyes on the glorious mantis shrimp:


    “Odontodactylus scyllarus 1” by Jens Petersen, via Wikimedia Commons

    Not all mantis shrimp are so brightly colored, but some – like the peacock mantis shrimp – are decked out in every color of the rainbow (and perhaps a few that only mantis shrimp can see).

  • Evil Disposition. All these powers packed into one creature might qualify mantis shrimp for membership in the Justice League, but they are no heroes. Behind the rainbow exterior, the exceptional vision, and the intimidating strength, lies the heart of a violent, ruthless predator.

    Mantis shrimp are merciless in their attacks on helpless prey, and they don’t limit their violence to obtaining food. Some species attack each other in ritualized displays of violence, assessing the strength of their rivals by punching them on the telson. This habit of violence toward each other is another reason mantis shrimp need such resilient armor.

The inescapable conclusion? Mantis shrimp possess exceptional vision, proficiency in violence, and strong defense. They are creatures of breathtaking beauty and bloodthirsty temperament. They are true supervillains.


“Mantis shrimp from front” by Jenny, via Wikimedia Commons

What other creatures do you think deserve to be called the supervillains (or superheroes) of the animal kingdom? Leave your suggestions in the comments!

*Odontodactylus scyllarus roughly translates to “tooth-finger Scylla,” an appropriately monstrous name for a mantis shrimp.

References:

Cronin, Thomas W., Roy L. Caldwell, and Justin Marshall. “Sensory adaptation: tunable colour vision in a mantis shrimp.” Nature 411, no. 6837 (2001): 547-548.
Cronin, Thomas W., and Justin Marshall. “Parallel processing and image analysis in the eyes of mantis shrimps.” The Biological Bulletin 200, no. 2 (2001): 177-183.
Cronin, Thomas W., N. Justin Marshall, Carole A. Quinn, and Christina A. King. “Ultraviolet photoreception in mantis shrimp.” Vision research 34, no. 11 (1994): 1443-1452.
Dingle, Hugh, and Roy L. Caldwell. “Ecology and morphology of feeding and agonistic behavior in mudflat stomatopods (Squillidae).” The Biological Bulletin 155, no. 1 (1978): 134-149.
Patek, S. N., and R. L. Caldwell. “Extreme impact and cavitation forces of a biological hammer: strike forces of the peacock mantis shrimp Odontodactylus scyllarus.” Journal of Experimental Biology 208, no. 19 (2005): 3655-3664.
Patek, S. N., W. L. Korff, and R. L. Caldwell. “Biomechanics: deadly strike mechanism of a mantis shrimp.” Nature 428, no. 6985 (2004): 819-820.
Taylor, J. R. A., and S. N. Patek. “Ritualized fighting and biological armor: the impact mechanics of the mantis shrimp’s telson.” The Journal of Experimental Biology 213, no. 20 (2010): 3496-3504.
Weaver, James C., Garrett W. Milliron, Ali Miserez, Kenneth Evans-Lutterodt, Steven Herrera, Isaias Gallana, William J. Mershon et al. “The stomatopod dactyl club: a formidable damage-tolerant biological hammer.” Science 336, no. 6086 (2012): 1275-1280.
Nathans, Jeremy, Darcy Thomas, and David S. Hogness. “Molecular genetics of human color vision: the genes encoding blue, green, and red pigments.” Science 232, no. 4747 (1986): 193-202.

See also:

Webcomic on mantis shrimp, by The Oatmeal.
Radiolab podcast on color, including a discussion on mantis shrimp vision and an full choir illustrating mantis shrimp vision through sound.