Is a jellyfish poisonous? Understanding jellyfish toxicity in one article

Jellyfish, also known as red jellyfish, flour jellyfish, fermented fish, etc., is a coelenterate of the genus Rhopilema, order Rhizostomeae, class Scyphozoa. Its umbrella-shaped bell is raised and bun-shaped, reaching 50 cm in diameter and up to 1 m at maximum. Its gelatinous body is fairly firm, usually blue-green, with milky-white tentacles and eight oral arms split into many lobes. It is widely distributed in the seas of both northern and southern China. Let us take a look below at whether jellyfish are poisonous.

Is a jellyfish poisonous?

Jellyfish are poisonous. After jellyfish venom stings the human body, it can cause injuries of varying degrees. For example, the sea wasp jellyfish, whose nematocysts can secrete a cobra-like venom, is the most harmful to humans and can cause death within 5 minutes after stinging. The Portuguese man o' war contains a “hypnotic toxin”, a toxin composed of polypeptides, proteins and small-molecule nitrogenous substances; after stinging a person, the patient often needs many days to eliminate the pain. Along the coast of China, the sand jellyfish, which drifts with cold currents in the Yellow Sea area, is commonly found and can secrete peptide toxins. Jellyfish toxins are stored and distributed within the nematocysts; 1 gram of nematocysts contains 55 million individual nematocysts. Generally, after harvesting, its toxicity can quickly disappear after processing.

Symptoms of jellyfish poisoning

The thin and delicate parts of human skin are the most easily stung. Generally, an electric-shock-like stinging pain appears within a few minutes, and several hours later the injured area gradually develops linearly arranged red papules with erythema, itching and burning pain. In mild cases, it can heal on its own in about 20 days. In highly sensitive patients, local redness, swelling, wheals, blisters, ecchymosis, and even epidermal necrosis may appear. Systemic manifestations in patients may include restlessness, chills, abdominal pain, diarrhea, listlessness, and chest tightness and shortness of breath. In severe cases, there are often episodes of coughing and wheezing, expectoration of white or pink frothy sputum, accompanied by signs of anaphylactic shock such as weak and rapid pulse, cyanotic skin and decreased blood pressure. If rescue is not timely, such sting patients may die within a short time.

The most venomous jellyfish

The box jellyfish is considered the most lethal jellyfish, bar none. The most venomous kind is called the “sea wasp” and can kill a person. These not-large (less than 20 cm in diameter), semi-transparent creatures are extremely dangerous to touch. They are highly toxic, hard to spot in the water, and swim very fast (over 4 km/h). Box jellyfish live in tropical seas, mostly in the shallow waters of Australian bays, and swim toward seaside bathing areas when the wind is calm and the sea is quiet. If someone touches the tiny cells on a box jellyfish, they may die very quickly. Along the coast of Queensland, Australia, over 25 years about 60 people died from box jellyfish poisoning, while only 13 died in the bellies of sharks during the same period.

Cases of jellyfish poisoning

On July 29, 1987, strong winds blew a large number of jellyfish into the Beidaihe seaside bathing beach. The jellyfish's long tentacles were like a young girl's hair, and its round “head” was as lovely as fine jade. Its swimming, contracting and expanding, was even more graceful and moving. Many bathers were misled by it and grabbed and hugged it with their hands. However, it was precisely in these “intimate embraces” that more than 600 people were stung. A young woman named Li Yunfen was poisoned extremely deeply and died after rescue efforts failed.

On August 11, 2014, a man traveling from Mudanjiang to Dalian and his friend went to Xinghai Bay Beach to have fun. At the seaside he heard a call for help. After swimming over, he found it was a girl, with a large jellyfish beside her, as big as an opened tent. He bravely pushed the jellyfish away, but was stung himself. That night, the man died after rescue efforts failed.

Note: Never catch or touch jellyfish drifting in seawater. Once stung by a jellyfish, do not rinse with fresh water, because fresh water can prompt the nematocysts to release venom. As soon as possible, use a towel, clothing, sand or mud to wipe away the tentacles or venom adhering to the skin, and wash the injured area with sodium bicarbonate (baking soda) or alum. If the injured area is large or the systemic reaction is severe, go to the hospital for treatment in time.