Wednesday, February 19, 2014

The Mantis Shrimp

photo from chicagonow.com

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Subclass: Hoplocarida
Order: Stomatopoda

The Mantis Shrimp- very beautiful to look at, but a complete terror in the marine world.

The Mantis Shrimp can be found in shallow waters off the shores of Palos Verdes and Catalina Island in southern California (Cabrillo Marine Aquarium). They are carnivores, and a deadly predator to other marine animals; they hunt for prey by means of stalking and sneak attacks as well as burrowing and waiting motionless for their prey before they snatch them. The Mantis Shrimp's diet includes small crustaceans, snails, clams, and fish.

Mantis Shrimp are not shrimp at all- they're crustaceans. They get their name only because they look like both a praying mantis and a shrimp. Their average size is about 12 inches in length. Reproduction varies among Mantis Shrimp. Some are monogamous, but most are polygamous. All Mantis Shrimp reproduce by sexual reproduction. This is initiated when a male Mantis Shrimp does a courtship fane to let a female know his intentions. (dept.lamar.edu) When they come together, the male will transfer sperm to the female. The female can then choose to retain the fertilized eggs, immediately lay the eggs in her burrow, or keep them on her forelimbs.

There are two characteristics of the Mantis Shrimp that I really want to get down to, though- their eyes and eyesight, and their incredible strength behind their punch and attacks.


First their eyes and sight. As you may know, humans have three types of color receptive "cones". These cones are green, blue, and red; the red cone allows us to see red and colors derived from red- like orange when yellow is added to red, or purple when blue is added to red. (The Oatmeal) Knowing this, imagine having TWELVE to TWENTY-ONE photoreceptors! ALL OF THE COLORS! According to an article by Sebastiaan Mathôt, he says that the upper and lower parts of the eye are like the typical compound eye, but it's the Mantis Shrimp's midband that gives the crustacean their incredible ability to see so many colors. However, even though Mantis Shrimp have the ability to see many different colors, they are TERRIBLE at distinguishing color differences. In the article written by Mathôt, he goes on to explain that scientists have done color discrimination tests on Mantis Shrimp to test their vision. This included using two optical cables in an aquarium that produced color; the crustaceans were trained so that they picked the cable with the specific color (and then they were rewarded with food!). The experiment showed that when the colors were very different, their task proved easy; when they were very close in color, the task proved hard. So it was concluded that Mantis Shrimp can only differentiate between colors that are about 12nm apart... humans can distinguish color differences as small as 1nm. (Awkward...) What a wasted talent! ...Maybe they're just overwhelmed with how many colors they can see. In all seriousness, there are many possible reasons for this, so I would definitely check out Mathôt's article, here, to read more on why the Mantis Shrimp have such trouble using their crazy color sight ability.

photo from UCMP Berkeley

Now onto their terrifying boxing gloves of appendages they have. You should ALWAYS take these little dudes seriously. Mantis Shrimp have what's called raptorial appendages on the front of their bodies; you can think of these like arms, if that helps. They can move these appendages extremely fast- two milliseconds, to be exact. (UCMP Berkeley) To put that into perspective, a blink is 100 milliseconds... but I wouldn't suggest blinking if you know one of these guys is stalking you. The other part of this appendage is what they call a "smasher", and they're freakishly powerful. (HULK SMASH!) Mantis Shrimp use this club-like part of their appendage to completely annihilate any animal with a hard shell. In fact, they can smash so hard, hard shells snap like butter being split by a knife. (Scared yet?) Get this: if their smasher was the size of a human fist, the force of its punch would be equivalent to a twenty-two caliber rifle (UCMP Berkeley); so, in other words... you're dead. If that's not a good comparison for you: a Mantis Shrimp can strike prey with 1,500 Newtons of force; if humans could throw at only ONE-TENTH that speed, we would be able to throw a baseball into orbit! (The Oatmeal)

There's more about their color vision and power punch in a great comic strip on The Oatmeal website. Check it out here: http://theoatmeal.com/comics/mantis_shrimp

Sure, the Mantis Shrimp may be beautiful, but these guys are insane. Have fun trying to sleep tonight.

I'm kidding. I will, though, leave you with this video from "True Facts". I would definitely watch this if you want to see their power punch in action (plus, the video is pretty funny).


4 comments:

  1. Great post! The strength that they have is incredible! This seems like a unique and helpful talent. There are a lot of violent predation techniques that I never knew went on in the Ocean such as this and the radula.

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  2. The power these little guys pack is incredible. Prior to reading this I would have had no fear in picking an animal like this up, but now I'm second guessing myself.

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  3. Julie, this is a great post! I had no idea that these organisms existed. I wonder why they aren't as 'publicized' as other organisms like octopi, sharks, etc. as they seem to be effective predators.

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  4. Great post on these cool crustaceans. Just to be clear, "real" shrimp are crustaceans too. But they are decapod crustaceans and mantis shrimp are malacostracan crustacean. Same subphylum, but different classes.

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