Cnidarians are a phylum of animals with a high diversity of aquatic species, which are distributed in both freshwater and s altwater ecosystems. One of the types of cnidarians are jellyfish. True jellyfish are exclusively marine and have a defense and hunting system that consists of inoculating their prey with a stinging substance. In the case of people, depending on the species, this substance can cause mild discomfort or death. In this PlanetAnimal file we will talk about a particular jellyfish, the Nomura jellyfish, whose scientific name is Nemopilema nomurai, an amazing cnidarian because of its size and its level of toxicity!
Origin
- Asia
- China
- North Korea
- South Korea
- Japan
Features of Nomura's Jellyfish
The Nomura jellyfish is a large cnidarian, it is also considered one of the largest existing jellyfish. In this article, you can learn about the largest jellyfish in the world. Its size can be greater than that of an adult person, that is, it can measure up to 2 meters in length, with a bell of 1.20 meters in diameter. They can easily weigh more than 200 kg. Their bodies are 90% water, and they have no eyes, brains, or airways. They have epithelial and striated muscle cells. Also, like other cnidarians, it has a hydroskeleton made up of a gelatinous substance called mesoglea. The color of this jellyfish is variable, gray or brown with light pink or white tentacles.
The nomura jellyfish is characterized by a complex, protein-like toxic venom that can cause various symptoms in humans, such as swelling and pain, but also death in high doses. Some studies have shown that there is variation in the venom of this species between individuals, which may explain the differences in levels of affectation in animals and humans.
Habitat of the Nomura jellyfish
The nomura jellyfish is found in China, Japan and Korea. According to monitoring reports, it is distributed in the southern and northern Yellow Sea, as well as the central China Sea. Massive sightings of young jellyfish of this species have been observed in Liaodong Bay during the summer season, while at the end of the season they tend to move to the central and northern Bohai Strait.
The size and weight of this animal make it prefer areas away from shore and at different depths, depending on the stage of its life cycle.It can therefore be found in shallow waters or on the seabed. However, most likely due to climate change, their populations are becoming increasingly abundant and are present in large numbers in coastal areas, leading people to fear them due to their toxins.
Habits of the Nomura Jellyfish
Previously, the Nomura jellyfish did not have a very high population growth and, although it was identified decades ago, it generally did not move to areas too close to the coast. But this situation has clearly changed over time, which poses problems both for man and for the jellyfish itself, since its large size means that it often gets caught in the fishing nets used by ships.
The Nomura jellyfish establishes certain associations with certain fish defined as parasites because, although these fish do not feed on the jellyfish, they camouflage themselves in its body to steal its food.In other cases, some fish feed on the cnidarian's body, damaging it so much that the jellyfish's umbrella breaks, causing it to sink to the bottom of the sea.
Nomura Jellyfish Feeding
Young specimens of this species of jellyfish feed mainly on zooplankton, which they catch with their tentacles. However, as they get older, they begin to vary their diet to include fish and shellfish. It is also common for them to consume fish eggs and larvae, which influences the decline in the population of certain species of their natural predators.
Reproduction of the Nomura jellyfish
The reproduction process of these animals is similar to that of other animals of their species, as you can read in our article on the reproduction of jellyfish. It is quite complex, as it is composed of sexual and asexual phases.In general, it begins with the fertilization of the eggs which, about the next day, are transformed into planulae, the larval forms of these animals. After 4-8 days, these larvae settle on a hard substrate to continue their development.
Once attached to the substrate, the larval forms pass to the stage called scyphistoma, where they undergo a series of transformations until they become young jellyfish, called ephyrids, characterized by their circular shape and composed of eight lobes. It takes up to 50 days for the jellyfish to reach the final appearance that it will maintain throughout its life.
State of conservation of the Nomura jellyfish
Nomura jellyfish populations are not currently reported under any criteria of danger or decline. On the contrary, the evidence points to unusual population growth. This increase is apparently linked to certain environmental issues, such as climate change, which is altering water temperatures in ways that create conditions for the species to reproduce more than they would naturally.On the other hand, overfishing could affect the decline of its natural predators, which also changes the balance of its population.