Nomura's jellyfish

Nomura's jellyfish is one of the biggest jellyfish in the world. It can reach about 2 metres wide and weigh up to 200 kilograms, a little wider than an average person is tall. It lives mostly in the waters of East Asia, especially the Yellow Sea and East China Sea.

Large blooms drift toward Japan and Korea in summer and autumn. When they become too thick, they can clog fishing nets and cause trouble for fishermen. It belongs to the group of rhizostome jellyfish, the same size class as the lion's mane jelly, the largest cnidarian. Its bell is translucent whitish, with pinkish or reddish oral arms.

Bloom trouble

Blooms seem to have grown more frequent between 1989 and 2009. Scientists think climate change, overfishing and coastal construction could help, because new surfaces give jellyfish polyps places to multiply. Korean sources say the animals can tear nets and also eat fish eggs and zooplankton. In the Tsushima Strait region, changes in the water in June and July carry young jellyfish along the current toward Japan.

Name and life cycle

The species is named for Kan'ichi Nomura, who sent a specimen in 1921. Its life cycle is like that of other rhizostome jellyfish. Its body is more than 90 percent water, and researchers are even studying its venom for medical uses. Fishing communities have suffered from the nets stuffed with jellyfish, so scientists look for uses for the catch.

On the globe

The model shows a giant Nomura's jellyfish drifting in the sea.