Watch out for those fists!
Photo: Silke Baron/Wikimedia Commons
In April 1998, a fierce creature named Tyson smashed through the quarter-inch-thick glass wall of his tank. He didn’t get far, however, as he was soon subdued by nervous attendants and moved to a more secure facility. Still, it was rather a big feat considering that, unlike his heavyweight namesake, Tyson was only four inches long.
The daring escape attempt is all the more remarkable as the animal accomplished it without claws. Instead, it used its powerful pair of what scientists call “raptorial appendages,” which end in a brutal hammer or a series of vicious, pointed spines. These prey-catching arms look much like the front legs of a praying mantis, which gives these creatures their name – mantis shrimps.
When Sheila Patek, a researcher at UC Berkeley, decided to study these heavy-hitters on video, she hit a snag. “None of our high speed video systems were fast enough to capture the movement accurately” she said. “Luckily, a BBC crew offered to rent us a super high speed camera as part of their series ‘Animal Camera’.”
With the top notch equipment at hand, the scientist managed to capture footage of one of these animals striking, slowed down over 800 times. Patek was mesmerized by what she saw. She found that with each punch, the club’s edge travels at about 50 mph, over twice as fast as previously estimated.
“The strike is one of the fastest limb movements in the animal kingdom”, Patek explained. “It’s especially impressive considering the substantial drag imposed by water.”
Since water is much denser than air, even the quickest martial artist would have considerable difficulty delivering a substantial punch in it. But it’s no problem for the mantis shrimp: it finishes a strike in under three thousandths of a second, out-punching even its land-living namesake.
How does he do it? A simple locking ratchet mechanism in its upper forearm allows it to store energy and then shoot it forward with an impressive acceleration exceeding that of a .22 caliber bullet, delivering over a whopping 1,500 Newtons of force.
And if that wasn’t enough, the shrimp movers its forearm club so quickly that it lowers the pressure of the water in front of it, causing it to boil! Then, with the water pressure normalizing, bubbles are released unleashing a great amount of energy as well – a phenomenon called cavitation.
So it’s no surprise, then, that if you get hit by one of these fierce little creatures, it hurts. A lot. Just look at this. Ouch.
According to some scientists, the mantis shrimp’s rather aggressive nature evolved because the rock crevices it inhabits are fiercely contested. The intensive competition in these spots has also made these animals smarter than the average shrimp. In fact, they are the only invertebrates that can recognize other individuals of their species and can remember the outcome of a fight against a rival for up to a month.
And there is more, still. Mantis shrimps have a way of seeing that’s unique in the animal world. Their compound eyes, which somewhat resemble those of a bee or fly, are made up of 10,000 small photoreceptive units, with some of them being arranged in a strip-like setup across their eyes. As a result, they see the world by scanning this strip across their subject, a bit like how a bar-code reader in a shop works.
Photo: prilfish
This means that, rather than relying on heavy brain processing to compare colors and determine what they are (as most vertebrates do), with the help of their photoreceptors mantis shrimps interpret information straight away.
Understanding how the mantis shrimp and other animals see the world has led to the development of a variety of practical applications for human technologies and medicine. Satellites, for example, use multiple spectral channels arranged in a strip to scan the world as they zoom over it before sending the information down to Earth – a mechanism very similar to how the mantis shrimp’s eyes work.
Truly amazing animals. One can only guess how many more staggering adaptations they have in stock that are yet to be discovered.
Sources: 1, 2, 3, 4, 5
