World’s Most Kick-ass Crustacean

I am a neuroscientist. I spend my time with a pipet in my hand. To be more accurate, these days I spend my time drooling in front of a computer eight hours a day (ahhh MRI research). I am about as far from the bottom of the Indio-Pacific Ocean as a person can be, physically and scientifically. But guys, in my very important attempts to keep up with the science literature in all disciplines (aka perusing Twitter) I have discovered the greatest animal ever… and I mean EVER. Move aside bunny rabbits, run in fear spotted leopards; even the naked mole rat has nothing on this guy (although naked mole rats are pretty awesome)

Everyone, I would like to introduce you to Odontodactylus scyllarus, a true BAMF (that stands for Big Angry Marine Fighter, Mom…).

More commonly known as a Peacock Mantis Shrimp, this incredible creature is not a peacock, a mantis, or a shrimp (first sign of bad-assery: An inaccurate pseudonym.). Instead, it’s a “smasher stomatopod” (dibs on that band name). I have conveniently broken down the amazing facts I’ve dug up into a list of why the peacock mantis shrimp is awesome.

I haven’t seen its name shortened this way in any of my research, but peacock mantis shrimp is kind of a mouthful, so I’m going to call it PMS. By the way, if having the initials PMS doesn’t tell you to run screaming for the hills, you clearly don’t spend a lot of time with women, and that’s ok. The bottom line is this: DON’T MESS WITH IT… EVER!

5.) Oooooh prettttty

It’s so psychedelically colorful, it looks like it was designed by Walt Disney on acid. If there were nothing more to it than its shell, it would still be fascinating. But don’t judge a lobstery crustacean thingy by its pretty exoskeleton- not only will this guy kick your ass, but all those colors actually serve a purpose. More on that later…

4.) LASERS!!

This video cracked me right up. Cuter than LOLcats any day, although people claim I have odd taste.

3.) Strike Force

From Biomechanics: Deadly strike mechanism of a mantis shrimp: “Mantis shrimp are the most speciose and geographically widespread group of organisms to use an appendage as a hammer; there are only a few other biological examples which include… Ankylosauria tails and human karate practitioners.” (Patek, Korff, & Caldwell, 2004) That’s right- the mantis shrimp is part dinosaur, part Chuck Norris.

While reading up on these magnificent beasts, I found somewhere that their striking arm moves so fast that it causes the water around it to boil. After my brain exploded from all the awesome, I sought to verify that fact. It turns out that’s not the most accurate description, but the truth is way better. Instead, the striking arm creates what are called “Cavitation bubbles.”(Patek & Caldwell, 2005) If you’re the kind of physics geek that really wants to know what that is, I’m working on a blog post specifically about it. Briefly, cavitation bubbles are the result of an area of negative pressure and are extremely unstable. When they implode, a force wave is sent out in all directions (as well as a light and sound wave– these things are LOUD!). For the PMS, that force wave is over 700 Newtons- more than capable of cracking shells. And skulls. Cavitation bubbles are formed when something moves at a high enough speed to f*** up the local pressure, and these babies are FAST. Using a saddle hinge mechanism (Patek et al 2007), they’re able to strike at 23 meters per second (~50 mph) but more importantly their peak acceleration is approximately 65-104 km/s. That’s roughly 10,400 g’s. Not impressed? Well that’s about the same peak acceleration as a .22 caliber bullet. A BULLET.

A BULLET.

Guys… I give you the YouTube proof:

Same peak acceleration as a .22 and done underwater by a little 10 cm guy? That calls for a 2-syllable DAAAAYUUUMN

Now you may be thinking to yourself, a bullet? Why, how could that be? Bullets are usually destroyed on impact, and that dude’s clubs look fine, so clearly you’ve been making stuff up again. Well that brings me to…

2.) Armor

Their clubs are so fascinating that according to the LA Times  the people who make lightweight bulletproof armor are turning to them for help in their designs. Much like nachos, layering is what makes the clubs awesome. There are three layers in the mantis club: the impact region, the periodic region, and the striated region (Weaver et al., 2012). The impact region is the outermost surface and is extremely hard, but relatively thin. Think of it as the tortilla chip. The next layer is the periodic region and is squishier and bouncier, thicker and less dense. Like melted cheese. The third layer is the striated region, and that switches stuff up. The minerals that make it lie flat, but each layer is turned in a slightly different direction. They eventually create what’s known as a “helicoid” structure. It’s all the random vegetables that get piled on top of the nachos. This structure can cushion against the high-energy collisions and prevent most cracks from forming, but its random nature means that cracks that form won’t result in a “catastrophic failure.” Basically, it isolates any structural damage so that it can’t ruin everything.

With the nacho club, the PMS can deliver blow after blow and hardly suffer any damage. When the club finally is worn out, the PMS can molt and make a brand new one.

1.) The eyes have it

And you thought YOU could see colors. Let me lay this out for you: human eyes see all the colors in this beautiful world through four different photoreceptors with three color channels. Fascinating right? Well keep your pants on, because PMS’s eyes have SIXTEEN PHOTORECEPTORS that can see TWELVE COLOR CHANNELS. Their vision is called “hyperspectral” which means they can see ultraviolet and infrared colors– they can see colors that we cannot even comprehend! I’ve said it before, but I’m a huge Radiolab fangirl, so I’m going to leave it to Jad and Robert to explain:

You can fastforward to around 15:30 to listen to the part specifically about mantis shrimp, but I would recommend listening to the whole thing. (And then going to the website and listening to everything they’ve ever put together. It’s sooo worth your time.)

Not only can they see more than we can imagine, but remember those crazy colors? They can see and SIGNAL with polarized light. There are two kinds of polarized light- linear and circular, and these buggers see with and use both. For more information on that I would check out this article, which opens with the best line I have ever seen in a high-impact journal:

I had intended to get through life without having to understand circularly polarised light. That hope has now been dashed by a flamboyant crustacean, the mantis shrimp”

(Land, 2008)

If he doesn’t want to figure out circularly polarized light, I’m not even going to try! For a better understanding I will send you here or  here.   This would probably help someone smarter than me understand circularly polarized light.

One more thing- each of their two eyes is adapted to be able to see with three different parts- that’s like having 6 eyes. With this adaptation, they have trinocular vision and depth perception– in each eye! If they were to lose an eye stalk in battle, they would STILL be able to see better than you can! Mantis shrimp have the most advanced eyes of any species on the planet.

Other stuff

Now, I’ve taken up a lot of space getting all worked up about an arthropod, so I’m going to leave you with only a few more tidbits. The next time you’re in the ocean keep an eye out for these guys, but I’ll give you a word of warning: In the diving community, they’re also known as “thumb splitters.”

(Note- some of these factoids are about species of mantis shrimp other than the PMS)

-When a mantis shrimp wants to get busy, it can actively fluoresce to signal to the ladies. Ladies love fluorescence. (Mazel et. al. 2004)

-Mantis shrimp will engage in ritualized fighting, but pull their punches so they don’t actually hurt anyone. They’re just playin’ (Taylor 2010)

-Mantis shrimp can recognize their pals by smelling them

-Like humans, some species of mantis shrimp will stay monogamous for decades. Other species are a bit more promiscuous. For the species that stick with the same partner they share their home and split up the chores, and the male and the female will share day-care responsibilities.

-The mantis shrimp is buoyant under water and can use its scuttly little legs to get around, but on land it’s too heavy. There’s one species of mantis shrimp that will sometimes get stranded on shore at low tides, and in that case it will SOMERSAULT ITS WAY BACK TO THE SEA. As in, put its nose to its butt and turn itself into a wheel. It has been observed rolling this way repeatedly for 2 meters. (Caldwell, 1979)

Sources:

Go here first

Caldwell, R. L. (1979). A unique form of locomotion in a stomatopod- backward somersaulting. Nature, 282, 71–73. doi:10.1038/282071a0
Land, M. (2008). Biological optics: circularly polarised crustaceans. Current biology : CB, 18(8), R348–9. doi:10.1016/j.cub.2008.02.030

Mazel, C.H., Cronin, T.W., Caldwell, R.L., & Marshall, N.J. (2004). Fluorescent enhancement of signaling in a mantis shrimp. Science, 303(5654), 51. doi:10.1126/science.1089803
Patek, S. N., & Caldwell, R. L. (2005). Extreme impact and cavitation forces of a biological hammer: strike forces of the peacock mantis shrimp Odontodactylus scyllarus. The Journal of experimental biology, 208(Pt 19), 3655–3664. doi:10.1242/jeb.01831
Patek, S. N., Korff, W. L., & Caldwell, R. L. (2004). Biomechanics: deadly strike mechanism of a mantis shrimp. Nature, 428(6985), 819–820. doi:10.1038/428819a

Patek, S.N., Nowroozi, B.N., Baio, J.E., Caldwell, R.L., & Summers, A.P. (2007). Linkage mecahnics and power amplification of the mantis shrimp’s strike. The Journal of experimental biology, 210(Pt 20), 3677-3688. doi:10.1242/jeb.006486
Taylor, J.R.A., & Patek, S.N. (2010). Ritualized fighting and biological armor: the impact mechanics of the mantis shrimp’s telson. The Journal of experimental biology, 213(Pt 20), 3496-3504. doi:10.1242/jeb.047233
Weaver, J. C., Milliron, G. W., Miserez, A., Evans-Lutterodt, K., Herrera, S., Gallana, I., Mershon, W. J., et al. (2012). The stomatopod dactyl club: a formidable damage-tolerant biological hammer. Science, 336(6086), 1275–1280. doi:10.1126/science.1218764

I’ve discovered that Roy Caldwell and Sheila Patek are the PMS gurus, so here’s a TED talk by Dr. Patek about how she discovered the extent of the PMS kick-assery

Finally, keep in mind I’m not a marine biologist so I could have misinterpreted something. If I did, let me know and I’ll correct it.

5 thoughts on “World’s Most Kick-ass Crustacean

  1. Came here via Cuttle. PMS is quite awesome but RadioLab isn’t. Gives me a migraine. Literally. And I figure they could cram about 5x as much info into a broadcast if they did it straight. IMHO of course

    • Thanks for stopping by! I admit, the more I understand about science the more I think RadioLab oversimplifies (and sometimes misinterprets) extremely complicated ideas. That being said, I think they do a great job of introducing non-scientists to a topic in an interesting way, and if the listener wants to know more there are resources on the RadioLab website for doing so. Without their jazzy little sound pieces and unique interview style, I’m not sure the show would sound much different from a lecture/seminar. I don’t know about you, but I go to enough seminars during the day! I can definitely see where you’re coming from though :)

      • Just purchased a mantis and wish I would have been aware of these before. Love the Radiolab, they do it goofy, yet kept my attention. Love it! Thanks for the info. Stay kewl!

  2. These guys actually make entertaining pets. Can be found at most fish stores that sell saltwater fish (AquaCritters) in Nashville. Just pay careful attention to your fingers when your cuddly crustacean decides to go for a stroll around the aquarium.

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