The Scyphozoa class encompasses more than 200 jellyfish species worldwide. While many prefer to remain close to shore, Scyphozoans in the Atolla genus have adapted to life deep in oceans where sunlight never reaches. All six Atolla species rely on bioluminescence — light they produce themselves — but the Atolla wyvillei uses the light in a defensive strategy that none of the other species employs.
Wyvellei jellyfish live in deep oceans throughout the world, from the Arctic to the Antarctic. They’ve also been found in the North Atlantic and Pacific, the Gulf of Mexico and waters around New Zealand. Their typical habitat ranges from 3,280 feet below the surface to more than 13,000 feet below the surface, where temperatures average between 29 degrees Fahrenheit and 2 degrees below zero Fahrenheit.
Atolla wyvilleis’ bodies, or bells, measure as little as 6/10 of an inch across to 8 inches across. A wyvillei usually has 22 marginal tentacles around the rim of the body and one hypertrophied tentacle, which might be 1.5 times to 36 times longer than the bell’s diameter.
Like many deep-sea denizens, Atolla wyvillei produce their own light, called bioluminescence. They use this ability differently than other animals, including the other five Atolla species, though. When a predator approaches, Atolla wyvillei emit a flashing blue light that attracts other, larger predators to gobble up the threat. Of all colors, blue reaches the greatest distance underwater. This defensive strategy has earned wyvillei the nickname “alarm jellyfish.”
Scientists are still studying how Atolla wyvillei use their hypertrophied tentacles, which coil and retract into the jellyfish’s bell. One theory suggests these tentacles passively trap food such as crustaceans and organic matter that float by in ocean currents. Scientists have speculated that the tentacles help in sexual reproduction by reaching out in search of potential mates.