| Lion's mane jellyfish | |
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| Conservation status | |
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Not evaluated (IUCN 3.1)
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Scyphozoa |
| Order: | Semaeostomeae |
| Family: | Cyaneidae |
| Genus: | Cyanea |
| Species: | C. capillata |
| Binomial name | |
| Cyanea capillata (Linnaeus, 1758) |
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The lion's mane jellyfish (Cyanea capillata) is the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans, seldom found farther south than 42°N latitude. Similar jellyfish, which may be the same species, are known to inhabit seas near Australia and New Zealand. The largest recorded specimen found, washed up on the shore of Massachusetts Bay in 1870, had a bell (body) with a diameter of 7 feet 6 inches (2.29 m) and tentacles 120 feet (37 m) long.[1]
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The taxonomy of the Cyanea species is not fully agreed upon; some zoologists have suggested that all species within the genus should be treated as one. Two distinct taxa, however, occur together in at least the eastern North Atlantic, with the blue jellyfish (Cyanea lamarckii Péron & Lesueur, 1810) differing in blue (not red) color and smaller size (10–20 cm diameter, rarely 35 cm). Populations in the western Pacific around Japan are sometimes distinguished as Cyanea nozakii Kisinouye, 1891, or as a race, Cyanea capillata nozakii.
Although capable of attaining a bell diameter of 2.5 metres (8.2 ft), these jellyfish can greatly vary in size, those found in lower latitudes are much smaller than their far northern counterparts with bells about 50 centimetres (20 in) in diameter. The tentacles of larger specimens may trail as long as 30 metres (98 ft) or more. These extremely sticky tentacles are grouped into eight clusters, each cluster containing over 100 tentacles,[2] arranged in a series of rows.
At 120 feet (37 m) in length, the largest known specimen was longer than a blue whale and is generally considered the longest known animal in the world.[1] However, in 1864, a Bootlace worm was found washed up on a Scottish shore that was 180 feet (55 m). But because bootlace worms can easily stretch to several times their natural length, it is possible the worm did not actually grow to be that length.
The bell is divided into eight lobes, giving it the appearance of an eight-pointed star. An ostentatiously tangled arrangement of colorful arms emanates from the centre of the bell, much shorter than the silvery, thin tentacles which emanate from the bell's subumbrella.
Size also dictates coloration—larger specimens are a vivid crimson to dark purple while smaller specimens grade to a lighter orange or tan. These jellyfish are named for their showy, trailing tentacles reminiscent of a lion's mane.
A coldwater species, this jellyfish cannot cope with warmer waters. The jellyfish are pelagic for most of their lives but tend to settle in shallow, sheltered bays towards the end of their one-year lifespan. In the open ocean, lion's mane jellyfish act as floating oases for certain species, such as shrimp, medusafish, butterfish, harvestfish, and juvenile prowfish, providing both a reliable source of food and protection from predators.
Predators of the lion's mane jellyfish include seabirds, larger fish such as Ocean sunfish, other jellyfish species, and sea turtles.[3] The jellyfish themselves feed mostly on zooplankton, small fish, ctenophores, and moon jellies.[4]
Lion's mane jellyfish remain mostly very near the surface at no more than 20 m depth, their slow pulsations weakly driving them forwards; they depend on ocean currents whereby the jellies travel great distances. The jellyfish are most often spotted during the late summer and autumn, when they have grown to a large size and the currents begin to sweep them closer to shore.
Like other jellyfish, Lions manes are capable of both sexual reproduction in the medusa stage and asexual reproduction in the polyp stage.[3] Lion's mane jellyfish have four different stages in their year long life span, a larval stage, a polyp stage, an ephyrae stage and the medusa stage.[3] The female jellyfish carries its fertilized eggs in its tentacle where the eggs grow into larva. When the larva are old enough, the female deposits them on a hard surface where the larva soon grow into polyps. The polyps begin to reproduce asexually, creating stacks of small creatures called ephyraes.[5] The individual ephyraes break off the stacks, where they eventually grow into the medusa stage and become full grown jellyfish.[6]
Most encounters cause temporary pain and localized redness.[7] In normal circumstances, and in healthy individuals, their stings are not known to be fatal.
On July 21, 2010, around 150 people are thought to have been stung by the remains of a dead Lion's mane jellyfish that had broken up into countless pieces in Rye, New Hampshire in the United States. Considering the size of the species, it is possible that this mass incident was caused by a single specimen.[8]