Don't let their small size and vibrant beauty fool you. The peacock mantis shrimp (Odontactylus scyllarus) can pack quite the punch! The peacock mantis shrimp, also known as the harlequin, painted, or clown mantis shrimp, is a captivating and formidable creature of the sea. These crustaceans boast a dazzling array of colors and possess remarkable hunting abilities, making them a subject of fascination for scientists and marine enthusiasts alike.
Description and Physical Characteristics
Peacock mantis shrimp are crustaceans, part of the same group of hard-shelled animals that includes crabs, lobsters, and shrimps. There are many species of mantis shrimp in the global ocean, and the peacock mantis is one of the largest. Peacock mantis shrimps typically grow to around 10cms (4 inches) in length, but some have been recorded to be as large as 46cms (18 inches).
Their bodies are bursting with bright colors like red, orange, green, and blue, with some spots on their forearms. Interestingly, females are mostly red while males have more variation in their coloration. Their size ranges from 1.2 to 7.1 inches and their narrow, hard-shelled bodies are covered in beautiful shades of orange, green, red and blue. The mantis shrimp’s shell (or ‘carapace’) covers only the rear part of the head and the first four segments of the thorax.
Unparalleled Vision
This species also holds the world record for the most complex visual system, able to sense many forms of light and color. The eyes of the mantis shrimp are located on the long stalks that can move independently. Their eyes are similar to crabs, bees, and butterflies in that they have compound eyes comprised of thousands of individual receptors that form the eye. Mantis shrimps have the most complex eyes in the animal kingdom and have the most complex visual system ever discovered. They can see a special spiraling type of light called circularly polarised light that’s not been documented in any other animal.
Peacock mantis shrimp have receptors that help them see UV light, visible and polarized light, and are the only animals known to detect circularly polarized light, which is a unique form of light wave. The mantis shrimp has 12-16 different color photoreceptors for color analysis in their retinas. This is three times as many photoreceptors as humans have. While they have significantly more color photoreceptors, research suggests they are actually worse at differentiating color than humans. However, scientists believe this is because their eyes are operating at a different level, functioning more like a satellite. This means that peacock mantis shrimp truly see the world in full color, able to see wavelengths that we can hardly even imagine! These shrimps have mobile eyes that can move independently from one another, allowing them to better locate their prey.
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Habitat and Distribution
Peacock mantis shrimp live in the warm waters of the Indian and Pacific Oceans. Their preferred habitats include coral reefs and sand flats at depths of up to 130 feet.
Hunting Prowess and Diet
These shrimps are feisty and able to kill prey many times larger than themselves using their raptorial appendages - club-like arms they fold underneath their bodies that look like the front legs of a praying mantis - to produce a pulverizing punch faster than the blink of an eye. Mantis shrimp are a violent predator and their diet depends on the species. They typically eat fish, crabs, clams, snails, worms, shrimp and squid. The most infamous species is the Peacock mantis shrimp (also known as harlequin mantis shrimp, painted mantis shrimp, or clown mantis shrimp), and is one of the larger, more colorful mantis shrimps commonly seen.
Peacock mantis shrimp are diurnal, opportunistic feeders, which is a fancy scientific way of saying they will eat any time of the day and are not very picky. Their usual diet consists of gastropods, crabs, and mollusks, and sometimes even other peacock mantis shrimp. To hunt, these shrimps often dig themselves into shallow, u-shaped burrows and remain almost completely still until an unsuspecting victim passes by. They unleash their powerful punches before their prey even realize what has happened, and the peacock mantis shrimp will approach it to feed on its tissue. Peacock mantis shrimp are very aggressive hunters and are active during the day and at night. Anything that enters the water is considered food until proven otherwise. Mantis shrimp seem to rarely ever be "full." My Peacock would certainly like to eat everyday, several times/day. Recommended portion size is a morsel no larger than about half the size of the upper carapace. That doesn't mean mantis shrimp won't enjoy larger portions. In one day I've seen my Peacock eat at least 2 emerald crabs that were probably 3/4-1" in diameter and still head out on foraging expeditions. My Peacock sweeps the entire tank many times throughout the day, digging in the substrate, moving rocks that aren't too big, etc. While some report a decrease in activity if they feed too much, my opinion is that this is the case only when a mantis is fed too much frozen food. If they're trained to "wait for the tongs to feed them" then they do often become lethargic and bound to their burrows. Conversely, if they know that their foraging will often be rewarded with live prey, they'll be much more willing to explore. This is a double-edged sword of course because live food is much more costly, there are some good live food choices that are manageable if bought in bulk (list at bottom).
Smasher vs. Spearer Diets
The two main types of Mantis Shrimp are Spearers, and Smashers. Spearers have an appendage that they can jab out and stab like a harpoon, generally hunting fish. Smashers use their club appendage and incredible speed to deliver the world's most powerful punch. They'll destroy just about any kind of crustacean with a shell, it hits the shell and will crack and break shells to bits and then take the meaty hunt to it's den. Well besides the fact that one eats fish and one eats crustaceans you have to understand one thing; their appendages need to be used or they will weaken as they molt. A smasher can even lose their appendage if it isn't fed hard shelled crustaceans regularly. They should generally be fed every other day, or two three times a week. As their size varies from a few inches to 8+, vary your diet accordingly. Both main types of Mantis Shrimp are extremely aggressive the only thing you should keep in that tank with the mantis shrimp is things you do not have a long love for. If the mantis shrimp is hungry it will eat at it's will. There isn't much that can compete with mantis shrimp, or it's speed. So keep this in mind. Smasher Live Food Diet: Generally speaking they'll eat anything they can smash. You can give them anything from hermit crabs, clams, lobsters, shrimp, emerald crabs, scallops, arrow crabs, snails, decorator crabs. You get the point, Anything with meat inside that it can smash open is perfect. Spearer Live Food Diet: Generally speaking they'll eat anything they can take down, everything from 1-12, even a lion fish your options are unlimited so nuff said. If you're giving a mantis shrimp frozen food, you can choose from a wide selection such as shrimp (cocktail shrimp are OK, squid, kill, even silver side chunks (available at LFS 90% time).
Additional Feeding Considerations
Mantis shrimp seem to be expert scavengers. If you want to make feeding frozen food more interesting, try putting a piece of frozen food in an empty shell and hide that somewhere in the tank. The mantis will smell it and come out looking. IMO it's better than just watching them take the food off the feeding utensil. Mantis shrimp have a wonderful sense of smell. I once noticed my Peacock swimming up into the water column underneath the spot where water returned to the tank from my HOB refugium. It seemed she was trying to swim up the waterfall into the refugium .
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-Emerald crabs, best purchased at LFS. If you do some shopping or speak to the manager, they might be able to cut you a nice deal. -Brine shrimp, again best purchased at an LFS. Relatively cheap at around $2 for an order that will last you several feedings. Trick is to keep the brine shrimp alive that long! I usually add some Selcon to their water and a few drops of Seachem to neutralize ammonia. For oxygenation I stir the water vigorously a few times per day. -Frozen clams on the half shell: I get the Hikari brand but there are others. These last a really long time and are great to soak in Selcon. Everything frozen should probably be soaked in Selcon for 5 mins or so to enhance nutrition. I usually place these as far from the burrow as possible. -Frozen krill/squid/shrimp: various owners have reported that their mantis shrimp seem picky about these meats. Some love krill, but hate squid, or vice versa. Find what works and go with that. -Ghost (glass/ditch) shrimp: these shrimp are brackish but are normally sold after being held in freshwater. I've never noticed any adverse affects of feeding freshwater shrimp, but it's an option that I don't use very often just to be safe. They are one of the cheaper live food options however. -Periwinkle snails: great for smaller mantis shrimp especially, these can be bought in bulk from reefcleaners.org. They're $0.15 each. Order 10 and you'll receive about 50, no joke. -Dwarf cerith/nassarius snails: can be found at an LFS but I like to buy in bulk from reefcleaners. You can specify the sizes that you want. I've found my Peacock struggles to get into the larger Nassarius snails but loves digging in the sand for small ones. -Hermits: size is important when buying hermits for food. Too big and the mantis won't be able to break them. Too small and the mantis might not exert the effort. I haven't had much luck with hermits, but they're relatively inexpensive and also act as valuable CUC members.
The Smasher's Punch
Their record-breaking punches have the same acceleration as a .22 caliber bullet, can superheat the water around it, and is one of the strongest pound-for-pound punches on planet Earth! Smashers can punch at the same velocity as a gunshot from a .22 caliber rifle. Smasher mantis shrimp have two raptorial appendages (called ‘dactyl clubs’) on the front of their bodies which they use to strike prey. These fists are able to accelerate from their body at over 50 mph, delivering a force of over 1,500 newtons -that’s 2.5k times the force of the shrimps own weight. Their punch is so fast it results in ‘cavitation’ bubbles. Beneath their hard-coated clubs, mantis shrimp have special layers of elastic polysaccharide chitin, which are positioned in a way to act as shock absorbers. This structure is called a Bouligand Structure, and it keeps small cracks from becoming a full break. Because their clubs can produce and withstand such incredible force, researchers believe that understanding these biological structures can help with the creation of stronger body armor, protective sports gear, and aerospace equipment. Mantis shrimp are territorial and are typically solitary outside of mating. This species will communicate through vibrations, known as stomatopod rumbles, which are used for territorial and defensive purposes. Individuals will create vibrations while in their burrows, warning potential predators and other shrimp to keep their distance. They may also use their powerful smashers to strike each other's tail areas.
Life Cycle and Reproduction
Peacock mantis shrimp start their lives as tiny larvae that move with the currents until they grow to be large enough to control their own motion. As they reach their juvenile life stage, they begin forming their shells, which they shed as they grow into adulthood. Their typical lifespan is between three and six years, though some individuals have lived to be twenty! Mantis shrimps carry their eggs with them while they are maturing to hatch.
Since they live in warm, food-rich waters, peacock mantis shrimp can reproduce several times each year, the timing of which depends on environmental conditions. Male peacock mantis shrimp are known to perform elaborate courtship dances for females and are aggressive toward other males. In both instances, they orient their bodies to show off the brightness and reflectivity of their colored patches. If a female accepts a male’s elaborate display, they reproduce via internal fertilization. This species is an oviparous, or egg-laying species, and females will carry thousands of fertilized eggs around on the front of her body, protecting and cleaning them until they hatch. Once the larvae hatch, they are on their own without any parental investment. Some peacock mantis shrimp form monogamous pair bonds. Some mantis shrimp species are monogamous, remaining with the same partner for life. Mantis shrimp pairs will live to together in the same burrow, and both the male and female take care of the eggs.
Threats and Conservation
The peacock mantis shrimp is not threatened or endangered, though scientists do lack long-term data that would help them see any population trends. As coral residents, the species is vulnerable to anthropogenic impacts that put reef ecosystems at risk. These include coastal development, overfishing, and ocean warming and acidification.
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Mantis Shrimp as Pets
Just wanted to post some thoughts I have regarding mantis shrimp feeding since it seems to be a common question for new hobbyists. It's important to note that mantis shrimp living in PVC pipes like mine seem to have trouble breaking through the toughest snail/hermit crab shells. This is because they don't have the depth/consistency of substrate needed to immobilize the prey before striking it. In the wild, Peacocks press the shell into the substrate and strike, allowing all of the force to be applied towards breaking the shell. In a PVC burrow, Peacocks can often be seen trying to press the shell down into the PVC itself similar to their tactics in the wild. Of course, the PVC prevents this and the end result is the mantis essentially knocking the shell all about the interior of the burrow without doing any real damage. Peacocks grow frustrated by this and will often expel the snail. Mine seems to have memorized which snails in the tank are off limits. The moral is that you can't just throw a bunch of snails in the tank and walk away. Confirm that the mantis is able to break into them. If it can't, get smaller snails. On that note they generally do not harm coral. There is a rumor among the aquarium world whether or not a mantis shrimp can break an aquarium. The answer is simple, don't be stupid and your won't get shot. I told you these creatures are highly aggressive, and most of the time they are purchased they are a grown adult male. While others introduced into the aquarium were hitchhiker that came with something else and sold off. The younger you get the better, just like any other animal in nature. The recommended tank size for Stomatopods is 30 or more gallons. Anything less and the glass is thinner, making it easier to bust if a hard impact hits it. The shrimp is still not giant, and his appendage is not very likely capable of breaking the aquarium unless it has outgrown that aquarium. For spearer mantis, using is deep sand bed is your best best with little rock work.
Smasher and Spearer Behavior
The name Mantis comes from their appearance. All mantis shrimp species have a second pair of prey-catching arms that are greatly enlarged. Dens: Their 'home' varies depending on species. As they have a shorter appendage than the spearer, they often don't dig a tunnel in the substrate. Instead they will typically seek refuge in the rocks. If you are planning a tank, try to create a small rock cavity to minimize the odds that your mantis shrimp will 'redecorate'. They are known to bust up small rocks to close their den, or even move frag discs to use as a door. *some species of smashers dig into coral colonies, and stony corals as it does naturally in the wild, while some would love to see this in their own aquarium, some would hate to see that on a prize show coral. Spearer Behavior: Spearers use their spear-like appendage to assassinate fish. If a fish swims near or close to it's burrow the mantis shrimp kills it by rapidly striking the fish with it's spear and pulling it deep into it's burrow. The most important thing to note about spearer mantis shrimp is that they do in fact burrow, they use their appendage to dig holes in the sand bed and us mucus to hold the sand together. It is for this reason that a Deep Sand Bed is very key to a happy and healthy mantis shrimp. Some species get large enough to need a 12 sand bed at times, while other one need a 3-6.