How Long Is the Lion’s Mane Jellyfish?

The lion’s mane jellyfish, Cyanea capillata, is one of the largest and most recognizable jellyfish species in the world. Characterized by a massive bell and long, flowing tentacles, its striking appearance has made it a notable subject in marine science.

Unveiling Its Stature

The lion’s mane jellyfish is renowned for its impressive dimensions, particularly the length of its tentacles. The largest recorded specimen, found off the coast of Massachusetts in 1865, had a bell diameter of approximately 2.1 meters (7 feet). Its tentacles extended an astonishing 36.6 meters (120 feet) in length, longer than a blue whale.

The bell, or umbrella, can reach up to 2.5 meters (8 feet) in diameter in the coldest waters, though average sizes are typically between 0.3 to 0.61 meters (1 to 2 feet). The immense length of their tentacles allows them to create a vast, drifting net to ensnare prey. This makes them one of the longest animals in the world.

Where Giants Roam

Lion’s mane jellyfish primarily inhabit the cold, boreal waters of the northern Atlantic, Pacific, and Arctic Oceans. They are commonly found in regions like the English Channel, Irish Sea, North Sea, and western Scandinavian waters. Their distribution extends along the coasts of North America and Europe, and they can also be found in the Baltic Sea, though low salinity prevents breeding.

These jellyfish prefer cooler waters and are rarely found in depths greater than 20 meters (66 feet). While found in open ocean environments, they are also encountered in coastal waters and sometimes shallow bays. Their movement relies heavily on ocean currents, as their slow pulsations do not allow for significant self-propulsion.

Beyond Length: Distinctive Traits

Beyond their remarkable size, lion’s mane jellyfish possess several other unique biological characteristics. Their coloration can vary, ranging from milky white or pale pink in younger individuals to reddish-brown, deep orange, or even violet in mature specimens. The bell itself is typically divided into eight lobes, giving it a distinctive star-like appearance.

Beneath the bell, they have numerous tentacles, organized into eight clusters, with each cluster containing 70 to 150 tentacles. A single large lion’s mane jellyfish can have as many as 1,200 tentacles in total. These tentacles are equipped with stinging cells called nematocysts, which are used to paralyze prey such as plankton, small fish, and other jellyfish. While their sting is painful to humans, it is rarely fatal. Even detached tentacle fragments can deliver a sting.