The mantis shrimp resembles the shrimp you eat, only it is about 5 inches long. It is interesting because it has shown the capability to develop a mind.

Mantis shrimp tend to cause havoc in aquariums, quickly demolishing the other forms of life and riddling the environment with tunnels, that allow it to quickly move from any part of the tank to any other, without observers seeing how they get there.

Jack Cohen and his students performed an experiment on the mantis shrimp. It was clear that it had some level of sophistication in its brain, but they wanted to see if it could develop a mind.

The began feeding it smaller shrimp, simply by dropping them into the tank. As soon as they got close to one of the tunnel openings, the mantis shrimp would pop out and eat the shrimp. After doing this for awhile, they placed the shrimp in a small plastic container. The first time they did this, the mantis shrimp wrestled with the container until it came open, and then ate the smaller shrimp from inside.

They continued feeding it shrimp in this way for awhile, and then they added a rubber band to the container, sealing it shut. The mantis shrimp took a little while to learn how to remove the band, but soon it could eat the shrimp from a banded plastic container easily.

After feeding the shrimp in this manner for some time, they returned to putting the shrimp in without any container. The first time they did this, the mantis shrimp seemed disappointed. It saw the shrimp outside of any container, and refused to eat it until it became too hungry to wait.

There is no way to prove this, but it is assumed that the shrimp was developing a primitive mind, and was beginning to enjoy the puzzles that it faced to get its food.

If this is true, it is proof of the theory of intelligence versus extelligence. These principles are beyond the scope of this writeup, but in its simplest form it states that for a mind to develop, it requires intelligence, but it will not develop in isolation. It also requires extelligence, meaning other sources of intelligence for it to interact with.

If the shrimp we ate were anything like mantis shrimp, there would be a whole lot of nine-fingered fishers out there; pound for pound, there is no more dangerous predator in or out of the ocean. The diving community has given them the apt nickname of "thumb splitters", and of the few people even aware of their existence, all most care to know is that these things can break your hand in a heartbeat. Biologists refer to them by the technical term stomatopods, and aside from a few adventurous aquarists, they are the only ones to appreciate the uniqueness and fascination of these crustaceans.

They belong to the diverse class Malacostraca, which encompasses shrimp as well as crabs and isopods (pillbugs); they belong to their own subclass Hoplocaridia (“armed shrimp”) and order Stomatopoda. They are further classified as either “spearers” or “smashers”, depending on the means by which they destroy their foes.

Mantis shrimp designated as spearers wield sharp blades at the ends of their arms, which can neatly hole much larger fish, octopi, or other soft-bodied animals. A dangerously barbed "finger" is folded up within a groove of this blade, able to snap out with the speed and force of a small-caliber bullet. Unfolding in eight milliseconds and travelling ten metres a second, it is among the fastest motions that any animal is capable of.

More aggressive still are the smashers, with massive, calcified elbow-clubs that they bring to bear against prey such as crabs, lobsters and clams. They frequently obliterate crustaceans much larger than themselves, reducing huge crabs to delicious fragments. Clams and snails are picked up, leaned carefully against rocks, and broken open. This variety of mantis shrimp has a deserved reputation for being able to shatter aquarium glass, although only the larger specimens have this level of strength.

Depending on their species, mantis shrimp grow from two to thirty centimetres in length. Their coloration ranges from drab gray or dun to a prismatic, riotous beauty. Although superficially resembling crayfish in their body structure -- an elongated carapace, eyes on stalks, and eight main legs followed by swimmerets and a flexible lobsterlike tail or telson -- their unique predatory arms make them immediately distinguishable.

One of the most fascinating aspects of stomatopod anatomy is their highly developed vision system, far surpassing that of humans and almost all other forms of life. Each crazily spinning, stalked compound eye has three separate regions: upper and lower hemispheres that serve mainly to pick out forms, separated by a color-sensing midband. As a consequence, each eye can see an object from three different perspectives, and has depth perception and trinocular vision on its own. (We need both eyes for depth perception and mere binocular vision.)

The middle band of the mantis shrimp's eye is equipped with ten different varieties of visual pigment, as opposed to our eye's three (red, green and blue). Eight of the mantis shrimp's pigments are dedicated to color vision alone; their visible spectrum, encompassing eight primary colors, is the key to a visual world unimaginable to humans. They can identify roughly ten thousand distinct colors, compared to the human maximum of one thousand. The additional pigments are dedicated to viewing the polarization and distribution of light, qualities human eyes can only faintly perceive, but which are essential in the low-contrast underwater landscape.

Their intelligence is likewise highly developed; researchers have shown it to be roughly equal to that of that notorious unbackboned intellectual, the octopus. Mantis shrimp can be trained to differentiate exceedingly similar colors and geometric shapes, and solve simple puzzles such as unwrapping a rubber band from a food item.

Mantis shrimp are the only invertebrates which can be consistently shown to discriminate between individual members of their species; this is probably a result of fierce competition for a limited amount of suitable living spaces, leading them to view competitors as unique individuals, and treat them intelligently. Certain species are even monogamous.

Stomatopods have a fairly wide distribution throughout the shallow and warm waters of the world, found ten to twenty metres down in areas as diverse as Indonesia, Florida, and the Isle of Wight. Some species burrow exclusively, tunneling through sand and mud, whereas others prefer pre-formed caverns in coral reefs and rocks. They spend the majority of time tucked neatly inside their lairs, waiting for unsuspecting creatures to come close; extremely wary of their relatively undefended backsides, they seek shelter whenever possible. Some species are known to block their lair entrances with rubble at night.

Like all crustaceans, they are egg-layers; the female can store fertilized eggs for three months or more after copulation. Eggs are exuded in a globby mass that she carries around with her until they hatch; typically the larvae leave immediately, although in a few species, they stay with their mother for a week or ten days before seeking their fortune, progressing through several larval and juvenile growth stages. Larvae are ferocious and cannibalistic, which explains the limited success of rearing them in home aquaria. Even in their earliest growth stages, their fearsome forelimbs are present, and frequently used to dismember other larvae.

The average lifespan of a captive mantis shrimp is three to four years, and researchers estimate that they may live much longer in their natural habitat, with certain species able to exceed twenty years.

The fascination of these creatures makes their relative obscurity all the stranger. They could teach us a thing or two; not just about eating clams and being pretty, but about percieving wonderful psychedelic landscapes, and kicking lots and lots of ass. And in the end, isn’t that what it’s all about?


Sources:
http://www.blueboard.com/mantis/
http://ozreef.org/reference/mantis_shrimp.html
http://www.x-entertainment.com/articles/0723/

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