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| Nomura's jellyfish | |
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| Nemopilema nomurai in theKaiyūkan-aquarium ofŌsaka | |
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| Size comparison of a Nomura's jellyfish next to a diver | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Scyphozoa |
| Order: | Rhizostomeae |
| Family: | Rhizostomatidae |
| Genus: | Nemopilema Kishinouye, 1922 |
| Species: | N. nomurai |
| Binomial name | |
| Nemopilema nomurai (Kishinouye, 1922) | |
| Synonyms | |
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Nomura's jellyfish (エチゼンクラゲ,echizen kurage;Nemopilema nomurai) is a very largerhizostomejellyfish, in the same size class as thelion's mane jellyfish, the largestcnidarian in the world. It is edible but not considered high quality.[1] It is the only species in themonotypic genusNemopilema. Commonly found in the waters of East Asia, and can negatively affect fisheries due to their large size and quantity. As a form of combating the large blooms, recent studies attempt to find new uses for the large jellyfish such as studying its venom for medical applications.
Nemopilema nomurai can grow up to 2 m (6 ft 7 in) in diameter and weigh up to 200 kg (440 lb), the diameter when fully grown is slightly greater than the height of an average human.[2] The species was named in tribute to Mr. Kan'ichi Nomura (C18–C19), Director General of theFukui Prefectural Fisheries Experimental Station, who in early December 1921 sent aspecimen in a 72-litre (16 imp gal; 19 US gal) wooden tank toProfessor Kishinouye, who found that it was unknown and dedicated time to study the living specimens.[3]
Nemopilema nomurai caught around Tsushima and the Iki Islands have 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.[4]
Nomura's jellyfish reside primarily in the waters between China and Japan, primarily centralized in theYellow Sea andEast China Sea.[5] Population blooms appeared to be increasing with frequency in the time period of 1989–2009.[6] Possible reasons for the population increase in Nomura's Jellyfish include climate change, overfishing, and coastal modification adding substrate for asexually producingpolyps.[5]
The life cycle ofNemopilema nomurai is very similar to that of other rhizostomes. Nomura's jellyfish are normally found in theYellow 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 theTsushima strait. In 2005 the largest blooms were in late October.[5] 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.[7]
This species of jellyfish feeds mostly onzooplankton 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.[7]
Whilejellyfish blooms have been documented in theSea of Japan since the writing of their first history book, the blooms ofNemopilema nomurai have been more recent. Since the beginning of the 20th century the instances ofN. nomurai explosive blooms have been on the increase, a fact not helped by their size — being one of the largest species of jellyfish recorded.[5] The largestN. nomurai blooms have been documented between the years of 2002 - 2003, during the time in which these blooms took place it was observed that the fishing industry was affected negatively.[8] The effects of the blooms can be seen in an event that took place in 2009, when a 10 tonnes (11 tons)fishing trawler, the Diasan Shinsho-maru, capsized offChiba onTokyo 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.[9][10]
Severe envenomations are becoming more common than ever. Victims of a sting from theN. Nomurai jellyfish may present symptoms of itching, swelling, acute pain, local erythrosis, and inflammation; in severe cases, the envenomations can cause death.[11] Recent research has also revealed that themyotoxicity caused by the presence ofNemopilema nomurai nematocyst venom (NnNV) in the body, which leads to Oedematogenic effects on the victims skin as well as resulting in thenecrosis of the muscle tissue in some cases can be prohibited bymetalloproteinase inhibitors such asbatimastat (BMT) andethylenediaminetetraacetic acid (EDTA).[12][13] The nematocyst venom of theN. nomurai is composed of complex, toxic mixtures of proteins. Further research is in progress to determine the key factors within these protein mixtures, which could predict specific symptoms from the venom and aid in treatment. Using experimentalomics-based approaches, research has revealed different sting related proteins and enzymatic components such as metalloproteinase and phospholipase A2s, as well as differences inhemolytic activity.[14] However, research has yet to provide a correlation between these components and symptoms of the envenomation.
Since the recent increase in blooms, research has been underway to find uses for Nomura's jellyfish. Each year this species costs Japanese fisheries serious damage and so an economic solution may be found in converting this invasion into a resource.[5]
The Japanese company Tango Jersey Dairy produces a vanilla and jellyfish ice cream using Nomura's jellyfish.[15][16] Consuming Echizen Kurage is potentially dangerous if the toxic part is not thoroughly cleaned and cooked.[17]
One patent suggested the use ofmucin of the Nomura's jellyfish to treat joint diseases such asosteoarthritis, although clinical data are lacking.[18] Although more research in the field is required, in recent cancer related studies it has been shown thatNemopilema nomurai jellyfish venom (NnV) can inhibitepithelial-mesenchymal transition (EMT) inHepG2 cells.[19] EMT aids in the early stages ofmetastasis, which is most commonly seen in cancer, and causes the cells to develop cancer like properties.[19] The study conducted showed that when cells with EMT were treated with NnV, it had a hindering effect on the EMT and the cancer like properties of the cells.[19]
Like many invasive species, such as thecane toad, a simple solution is to take the species and convert them into fertilizer. Another study aimed at using an aqueousmethanol extract of dried medusa to inhibit the growth of weed seedlings when added to the soil.[20]
Drs Toyokawa Masaya & Kensuke Yanagi kindly informed about Kanichi Nomura...
