Wednesday, July 9, 2014

SCIENCE of the Mantis Shrimp

Hello All,

So some of you may have seen the following infographic from The Oatmeal about the amazing eyesight of the Mantis Shrimp.  This infographic subsequently made the Mantis Shrimp my spirit animal.


Upon reading this infographic, I immediately wasted hours on the internet seeing how much of this was true.  Actually, there is a lot we don't know about mantis shrimps, mostly because they are solitary and spend most of their lives in crevasses, but there are about 400 species of them currently described.  And the name "Mantis" came from their similarities in hunting to the praying mantis insect.  And now I'm breaking down this infographic into myth and reality.

1. The Mantis Shrimp has SIXTEEN color-receptive cones (Humans have three), so they must see an amazing spectrum of colors that we can't even imagine.  

Yes, their biology shows that they do in fact have 16 receptors, this hasn't been shown to translate into extremely precise color distinction.  A study done at the University of Queensland in Australia trained a species of mantis shrimp to recognize a particular color.  They were then given the opportunity to choose between a burrow of that color and a color similar to it on the spectrum.  When the colors were different (think teal versus turquoise), the mantis shrimp were able to discern the color, but when the colors got closer and closer in similarity, the shrimp did no better than just making random guesses.  Humans can distinguish between as small as 1 nanometer of color, but the mantis shrimp wasn't able to accurately discern between 15 nanometers.  However, they can see ultraviolet (UV) light, something we will never see.  So basically, they can see a wider spectrum of color, but not each color individually.  But wait, UV light should be damaging, right?  Not for mantis shrimp!  They have a biological sunscreen that both allows them to see UV light and protects their eyes and the rest of their body.  They are also the only animals that can detect circularly polarized light (light waves that form a spiral pattern.  I don't know what it is either).  But check out its eye movements!

     

2. They're actually super colorful.

I'll let you decide (hint: if you think no, then you're wrong)

3. The mantis shrimp is an undersea nightmare.  

Actually, they spend most of their lives by themselves.  They are very smart animals, able to recognize their neighbors and display defense mechanisms against those neighbors.  They can go through over 20 breeding episodes, and both sexes take care of the eggs.  In some species, the shrimps mate for life, and can stay with their partner for over 20 years (mantis shrimp have a very long lifespan).  So I would say that they make good parents, only kill for food, and are smart enough to stay away from predators, so I would give this a rating of "myth".  

4. Its front appendages can accelerate at the same velocity as a rifle.  This makes the water boil at several thousand Kelvins.  

There are two hunting techniques of mantis shrimps depending on the species: smashing and spearing.  Smashing involves using their clubs to crack the shells of their prey and eat the insides, while spearing involves using barbs to stab soft animals like fish and allow the shrimp to cut their meat.  The hit of the smashers may reach the power of a .22 bullet.  They are called "thumb splitters" because they can inflict deep cuts into fingers when handled.  No concrete evidence as to the water boiling, temperatures that high, or sparking water.  And there are plenty of videos and articles to show this (lack of) evidence.

5. The mantis shrimp primarily kills via dismemberment.  

Watch this cool video that shows how a mantis shrimp attacks a crab to find out!  After the initial few strikes, you can skip forward to 2:00 to watch more.  And while it's definitely not the diabolical soul-crushing death that was described in the infographic, but still cool to watch.



6. Their armor is a template for building new body armor.  

Recently, a material based on the exoskeleton structure of mantis shrimp has been created, and it's stronger than what is currently used in airplane frames!  What's so cool about its armor?  It is of particular interest because it can withstand thousands of intense impacts (the appendages of death).  The structure of the cells of the exoskeleton is a new design, and the special stacking of the cells that is seen in the armor is what is being copied.  Who knows?  We already ride in planes modeled after sharks, maybe we'll soon fly in planes made of mantis shrimp armor.

7. They break glass in aquariums.  

While mantis shrimp seem to have the power to do so, they don't seem to want to.  They are held in aquariums often, and even sold as pets.  Mantis shrimp seem to only use their appendages of death when directly threatened, by someone poking at it with a stick or when there is food present.  They don't just attack, as what it seems like in the infographic.  A simple YouTube search can find that mantis shrimp are kept in aquariums all around the world with no issue.  

So that's my breakdown of The Oatmeal's infographic.  They definitely hit on the amazing things about the mantis shrimp, but there are some areas where they should have done their research first before posting.

Also, you can buy mantis shrimp plushies!  I don't have $40 to buy one, but maybe for Christmas?

So although the mantis shrimp isn't all it was cracked up to be by The Oatmeal, it's still my favorite animal, and I hope you enjoyed reading!

Kim


Works Cited

http://life-sea.blogspot.com/2012/06/life-of-mantis-shrimp.html

http://wildthings.sarahzielinski.com/blog/what-the-oatmeal-might-have-gotten-wrong-about-mantis-shrimp/

http://www.iflscience.com/plants-and-animals/mantis-shrimp-use-natures-sunscreen-tune-uv-vision

http://www.iflscience.com/technology/mantis-shrimp-inspired-material-stronger-airplanes

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