The Odontodactylus Scyllarus, more colloquially referred to as the peacock mantis shrimp, gets its name from its bright peacock-like coloration, its shrimp-like size, and its mantis-like body structure. The mantis shrimp belongs to the kingdom Animalia, the phylum Arthropoda, the subphylum Crustacea, the class Malacostraca, the order Stomatopoda, the family Odontodactylidae, and the genus Odontodactylus (Wikipedia). This species, the Odontodactylus Scyllarus, belongs to a group of 400 other types of mantis shrimp whose lineage can be traced back using phylogenies 500 million years (Guenther).
Typically, the size of a peacock mantis shrimp ranges from three to eighteen inches in length (Wikipedia). Because they live in subtropical and tropical marine environments, this species can be found in the warm shallow waters of the Indian and Pacific Oceans ranging from Guam to East Africa. Mantis shrimp live in crevices of coral rocks on the ocean floor in burrows three to forty meters deep. Because of some of its distinctive physical features, the peacock mantis shrimp has a stable population (National Aquarium). The peacock mantis shrimp has an extremely distinct physical appearance.
Its hard-shelled body is full of vibrant colors and its forearms are covered in spots resembling the colors and patterns of a peacock’s tail (The Oatmeal). The peacock mantis shrimp has an exoskeleton and they must molt in order to grow. Every several months the shrimp begins to outgrow its exoskeleton and sheds the entire thing, leaving behind a complete mold of its body. This process can be problematic for the shrimp as their new armor does not harden right away, leaving them exposed to predators and the elements of their environment (Duke University).
An additional distinctive feature of the peacock mantis shrimp are its two raptorial appendages on the front of its body. They use these appendages to smash its prey, thus dubbing it a “smasher” (Wikipedia). The mantis shrimp packs a significant amount of strength and speed into its small body. The speed of their punch is equal to that of a . 22 caliber bullet and one strike is fifty times faster than the blink of a human eye. In less than three thousandths of a second peacock mantis shrimp can strike prey with 1,500 Newtons of force (Guenther).
They use the strength of their clubs to break the shells of their prey such as oysters and crabs and have often used their claws to break aquarium glass, thus making this species extremely difficult to keep in captivity (Kiem). These clubs are spring loaded, similar to a crossbow and use a system of biological springs, latches and levers to power their fast strikes. Upon release, their clubs accelerate at over 50 miles per hour with a force of over 330 pounds; this is up to 2500 times the shrimp’s own weight (Guenther). These limbs have a Bouligland structure (Duke University).
The surface of its appendages are made up of extremely dense hydroxyapatite and their shock absorbent core have a molecular structure different from any other animal. It is this mechanism that allows shrimp to punch repeatedly, breaking the shells of their prey without breaking their own limbs. Peacock mantis shrimp move their limbs so quickly that the water around them boils, this creates pockets of air called cavitation bubbles. When these bubbles collapse, they cause small implosions of heat, light, and sound in water that allows them to kill their prey without directly touching them.
The force of these collapsing bubbles produces temperature in the range of several thousand kelvins and emits a sort of supersonic light called sonoluminescence. This entire process of using the strength and speed of their limbs to indirectly attack their prey is called supercavitation (National Aquarium). From an evolutionary standpoint, the impact region their clubbed limbs are composed of a key mineral also found in human bone. Additionally, the peacock mantis shrimp’s claws have evolved to many different shapes and have been able to do so independently, without compromising the mantis forceful blow (Duke University).
The eyes of the peacock mantis shrimp are also unique. Each eye is located on a stalk on their heads and can move independently and in different directions. Further, this species has the broadest visual spectrum of any animal. The peacock mantis shrimp has sixteen color-receptive cones which means they can see many more colors than humans, who have only three (The Oatmeal). Because of the Rhabdom, the part of this shrimp’s photoreceptors responsible for detecting different light vibrations, this species can detect circularly polarized and ultraviolent light.
Each line of the mid-band of their eyes has different photoreceptors, which detect different wavelengths and interpret colors. Additionally, this species uses the dorsal and ventral hemispheres of the brain to detect form and motion (Cole). Overall, the peacock mantis shrimp’s specific features and adaptations have occurred to best suit its lifestyle and actions. Peacock mantis shrimp are monogamous maters and typically have the same mate for twenty years. They cohabitate with their mate, sharing the same burrow, as well as sharing the responsibilities of protecting their eggs and hunting.
They do not leave their home burrow unless they are hunting or forced to move. Being extremely territorial and aggressive animals, they prefer to ambush their prey from their burrows as opposed to going out to hunt. By staying close to their burrows, especially in times when they are molting, peacock mantis shrimp can better avoid their predators which are made up of primarily large fish (Guenther). This species preys on crabs, mollusks, oysters, octopi, and other fish, using dismemberment and bashing as their weapon of choice.
The mantis shrimp does not frequent aquariums because it can kill all of the fish in the tank with it, and even if left alone they can still break the aquarium glass (Kiem). Because of their unique physical features and adaptations, the peacock mantis shrimp is being studied by scientists for several reasons. Specifically, engineers are studying the composition of the peacock mantis shrimp’s limbs to design lighter and stronger materials for military use as well as studying the resilient cell structure of their limbs to create body armor of troops (The Oatmeal).
Scientists are also attempting to mimic the Bouligland structure of the mantis shrimp to design thin, light materials strong enough to stop explosives and build stronger frames for machines such as cars. Scientists are also studying the mantis shrimp’s eyes in an attempt to build small cameras that can detect cancer cells in early stages and to determine if the mechanisms by which their eyes operate can be replicated for use in reading CDs and other optical information storage devices (Kiem). Peacock mantis shrimp are unlike any other species. They have an otherworldly beauty and yet are characterized by devastating violence.
They are a pinnacle of evolutionary achievement, a species that defies captivity as an apex predator, and is packed with unique biological innovations. Not only did I learn about a fascinating new species that I previously did not know existed, but I was also able to see through this species the way in which evolution and adaptation allows for unique niche species dominate certain ecosystems. Though the peacock mantis shrimp is small, beautiful, and may seem like a small species in a big sea, its distinctive biological features allow for it to be a powerful predator that packs an even more powerful punch.