Nomura's jellyfish (エチゼンクラゲ, echizen kurage, Nemopilema nomurai) is a very large rhizostome jellyfish, in the same size class as the lion's mane jellyfish, the largest cnidarian in the world. It is edible but not considered high quality. It is the only species in the monotypic genus Nemopilema.
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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starts withThe diameter when fully grown is slightly greater than the height of an average human. The species was named in tribute to Mr. Kan'ichi Nomura (C18–C19), Director General of the Fukui Prefectural Fisheries Experimental Station, who in early December 1921 sent a specimen in a 72-litre (16 imp gal; 19 US gal) wooden tank to Professor Kishinouye, who found that it was unknown and spent some time at the station to study living specimens.
Growing up to 2 m (6 ft 7 in) in diameter and weighing up to 200 kg (440 lb), Nomura's jellyfish reside primarily in the waters between China and Japan, primarily centralized in the Yellow Sea and East China Sea. Population blooms appeared to be increasing with frequency in the time period of 1989–2009. Possible reasons for the population increase in Nomura's Jellyfish include climate change, overfishing, and coastal modification adding substrate for asexually producing polyps.
The organism Nemopilema nomurai is one of the largest of all jellyfish species, attaining a bell diameter of ca. 2 m and a wet weight of ca. 200 kg (Kawahara, 2006). Nemopilema nomurai caught around Tsushima and the Iki Islands had a translucent whitish body, with pinkish or reddish capulets and oral arms, and transparent immature gonads.Jellyfish have two main types of muscle: epitheliomuscular cells and striated muscle cells. Researchers found that gene families that are closely associated with striated muscle were expressed in the bell portion of the jellyfish, providing evidence that striated muscle plays a significant role in jellyfish motility.
In 2009, a 10 tonnes (11 tons) fishing trawler, the Diasan Shinsho-maru, capsized off Chiba on Tokyo Bay as its three-man crew tried to haul in a net containing dozens of Nomura's jellyfish; the three were rescued by another trawler.
While jellyfish blooms have been documented in the Sea of Japan since the writing of their first history book, the blooms of Nemopilema nomurai have been more recent. Since the beginning of the 20th century the instances of N. nomurai explosive blooms have been on the increase, a fact not helped by their size — being one of the largest species of jellyfish recorded. This species of jellyfish feeds mostly on zooplankton in all stages of life, feeding on larger fish as they grow larger. Their only predators consist of swordfish, tuna, sunfish, leatherback turtles and humans.
The life cycle of Nemopilema nomurai is very similar to that of other rhizostomes. Nomura’s jellyfish are normally found in the Yellow Sea and populations are generally maintained there year round. During June and July changes in the water salinity lead to the expatriation of larval stage jellyfish via the Tsushima strait. In 2005 the largest blooms were in late October. It is noted that this species of jellyfish in six months can grow from the size of a grain of rice to greater than 6 ft (1.8 m) wide.
