A Bullet of Colors: The Mantis Shrimp
The arthropods are, without doubt, one of the largest phylum in the kingdom of Animalia, with an estimated of 10 million of species in the world, with more being discovered every day. If you look outside your window, probability says you will see one. Flies, wasps, bees, ants, butterflies, even spiders, are all around you, even if you don’t notice, and they are as frequent as humans, or even more. Wherever you go, logic says you see some arthropod; the woodlice living in a rotting log, that bee drinking nectar, a scorpion resting on top of a rock, and more.
And, the sea is no different. Even as children, we associate certain arthropods to the beach and the ocean, like crabs, rolling around in the sand, the barnacles clinging to a ship, and shrimp living in the sea; those we see at the sea, most probably, are crustaceans, a diverse group of animals with hard shell.
When one thinks of crustaceans, one would think of crabs, or shrimps, lobsters. And, unless you have watched one too many programs in Discovery Channel (I would know!), one wouldn’t think of the Shrimp Mantis.
What is the Mantis Shrimp?
The Shrimp Mantis, or scientifically known as Stomatopods, is a marine crustaceans that is mostly known for its ability to punch really hard, or to see colors which humans cannot see. But, of course, there is more to it. The mantis shrimp is, contrary to its name, not actually a shrimp; the stomatopods, while part of the same class that has shrimps, diverted from that evolutionary path over 300 million of years ago, and are their own order altogether, with 450 known species, that range from brightly colorful (such as the peacock mantis shrimp) to pale and dull colors (such as the cape mantis shrimp).
The stomatopods live in tropical and sub-tropical habitats, one of the most important predators of those areas, and are commonly found in the Pacific and Indian oceans between eastern Africa and Hawaii; they can grow up to 10 cm but some specimens have been known to grow up to 38 cm. They live alone, in small burrows or holes, where they lay down and wait for prey to pass by, which they then hunt and drag back to their den. Their attack weapon, the raptorials, are widely regarded as powerful, and it is with those that they attack and kill their prey. They feed on fish, worms, crabs and shrimp.
Fun Facts about the Mantis Shrimp
Their raptorials can be either be spiny and topped with barbed tips, which classifies them as spearers, or can be more club-like and rudimentary, which classifies them as smashers. The punch of a smasher is said to have the acceleration of 10,400g and a speed of 23m/s, being so fast that the water around the place that gets hit is vaporized, leaving vapor-filled bubbles behind, called cavitation bubbles.
But, without a doubt, one of the most important characteristics of a mantis shrimp is the eyes, which has been the focus of scientific interest for years. They can be capable of moving independently of one another, and have the biggest amount of photoreceptor in the animal kingdom, between 12 to 16 (thrice the amount of photoreceptors in a human!), which grants them the title of the animal with the most complex eyes, capable of distinguishing color, as well as polarized light and visible UV light.
While it is said that mantis shrimp can see hues of colors that humans do not, that is in fact, not true. While humans detect up to 1–5 nanometres, the animal can only distinguish from 650 to 50 nanometres; what the stomatopod focuses on is, instead of discriminating between colors, is identifying colors, dedicating each photoreceptor to a specific color or light, which allows them to process the information faster.
It is theorized that they have such complex eyes to allow them to identify prey easier, as well as identify fellow members of the species and communicate, since they could have markings alongside their body which can only be seen under UV light or polarized light. Despite being such an interesting order of animals, there is not much knowledge about the mantis shrimp, and investigations are still discovering new facets of this fascinating animal everyday.
Even kept as pets, the mantis shrimp has captivated the attention of whoever learns of them, with the power of boiling water with a punch and seeing lights like no one else. Only the future can tell what else will we learn about this fascinating animal.
SOURCES
Cover photo by Photo by Amber Wolfe on Unsplash
Thoen, H. H., How, M. J., Chiou, T.-H., & Marshall, J. (2014). A Different Form of Color Vision in Mantis Shrimp. Science, 343(6169), 411–413. doi:10.1126/science.1245824
Patek, S. N., Korff, W. L., & Caldwell, R. L. (2004). Deadly strike mechanism of a mantis shrimp. Nature, 428(6985), 819–820. doi:10.1038/428819a
