Lion's mane jellyfish

The lion's mane jellyfish (Cyanea capillata) is one of the largest known jellyfish. It lives in cold northern waters of the Arctic, North Atlantic and North Pacific, and it is common in the North Sea and around Scandinavia. Look for it in the English Channel, the Irish Sea and the North Sea.

It is named for its long, trailing tentacles that look like a lion's mane. The biggest one on record, found off Massachusetts in 1865, had a bell 2.1 metres across and tentacles about 36.6 metres long, which is longer than a blue whale. Its sting is painful.

Built like a star

The bell of most jellyfish is round, but the lion's mane has a bell divided into eight lobes, like an eight-point star. Each lobe holds about 70 to 150 tentacles in four fairly clear rows.

Young jellyfish are light orange or tan and darken to red and purple as they age. A jellyfish at lower latitudes is usually smaller, with a bell about 50 centimetres across.

Drifting through the sea

Most live in the top 20 metres of the sea and drift with the currents, each one moving alone rather than in a group. They are seen most often in late summer and autumn.

They use their tentacles to catch fish and plankton. In the eastern North Atlantic a smaller, blue relative, Cyanea lamarckii, lives alongside it. Some zoologists even think all the Cyanea species could be one, so the family tree is still being worked out. The jellyfish can also drift outside its usual waters during warm spells, even into the southwestern Baltic Sea, though it cannot breed there because the water is not salty enough.

On the globe

The model shows a lion's mane jellyfish with its mane of trailing tentacles in the cold northern sea.