Science Interviews

Interview

Sat, 11th Dec 2010

Fastest claws in town

Listen Now    Download as mp3 from the show The 12 Critters of Christmas

Mantis shrimp have a lightening fast punch and the most complex eyes in the animal kingdom.

Sarah – For our 6th Xmas critter we’re going to be venturing out to the tropical coral reefs for one of my personal favourite species, which is the mantis shrimp.

Mantis ShrimpThese are like the Kung Fu masters of the ocean world. They’re found all around the world in both tropical and subtropical seas.

They range from only just a few cms, so a couple of inches long, up to around 30cm, which is about 12 inches. And they can shoot out their front claws which are either shaped like spears or clubs, which is why they earned the names mantis shrimps because they look a little bit like preying mantises – and they can shoot those out at around 23m/s with an acceleration of over 100,000 m/s2, which is equivalent to the speed of a speeding bullet.

And they also have the most elaborate and complex eyes of any animal on the planet.

So let’s start with their claws. Different species use their claws in different ways. Some have these barbed, spearing claws to jab out a soft prey like fish. And others have club-like claws that they use to break open harder prey like snails and crabs.

These claws shoot out from the mantis shrimp so fast that they actually create little collapsing bubbles that make a pop like a small sonic boom. And they can even sometimes produce a tiny bit of light as the energy produced is so high.

The shock wave created by the bubbles collapsing is actually enough o stun the prey so even if they don’t hit it with their claws they can still get it afterwards.

Not that they would be likely to miss their prey with their claws because of their incredible sense of vision.

Like other arthropods including other crustaceans like crabs and lobsters as well as insects and spiders, mantis shrimps have compound eyes.

These are made up of lots of tiny little eyes called omatidia, each with its own lens and light and colour-sensing pigments. 

We have 4 different types of photoreceptor pigments in our eyes. One type in the rod cells that senses the brightness of light, and 3 types in the cones that detect different wavelengths of coloured light.

Mantis shrimps have 16 different types of pigments. They can see infra red, and ultra violet light as well as polarized light. And the position of their eyes on movable stalks also means they have accurate depth perception. Obviously very useful for aiming your strikes at your prey.

So, although they’re quite small, those mantis shrimps, you certainly wouldn’t want to mess with them.

Another name for them is thumb splitters because they can give a nasty injury if you get them annoyed.

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