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Do Jellyfish Have the Deadliest Venom in the World?

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Do Jellyfish Have the Deadliest Venom in the World?

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Jellyfish Nematocysts: A Sting Operation - Jellyfish Nematocysts | HowStuffWorks

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You may have been stung by a jellyfish on a trip to the beach or a dip in the ocean. But, while most jellyfish stings do little more than annoy you, the sting of the box jellyfish can literally scar you for life -- if it doesn't kill you first.

The venom of this pale blue, almost transparent, invertebrate is among the most deadly in the world, capable of killing a human in under five minutes [source: Thompson]. This animal has enough venom to take out 60 adults [source: Bartalucci]. Also called sea wasp and marine stinger, the box jellyfish injects its venom by way of the many tentacles dangling from its bell, or body. (The box jelly gets its name from the boxy shape of its bell.) Each tentacle contains about 5,000 stinging nematocysts, housed in cells called cnidoblasts. Nematocysts are like little stinging darts that fire whenever the tentacle comes in contact with chemicals on the surface of its prey. (You can learn more about various species of jellyfish by reading How Jellyfish Work.)

With up to 15 tentacles growing from each corner of the jelly's bell, and each one reaching a possible 10 feet (3 meters), that's a lot of miniharpoons ready to deliver venom into a victim's body. A single encounter can leave you with thousands of stings, and the powerful venom doesn't waste any time getting to work. Many victims stung at sea go into shock or die of heart failure before they can even reach the shore [source: National Geographic].

Not only is the box jellyfish venom damaging to the heart and nervous system, it's also dermonecrotic, meaning it's capable of killing skin cells and underlying tissue, leaving you with dead, blackened skin and potentially permanent scarring. To make matters worse, your initial instinct to shake the offending stingers off makes the tentacles contract and stick tighter to your skin, possibly releasing even more stingers into your already burning flesh.

Thankfully, there's somewhat of a cure if you can get to it fast enough. Acetic acid solutions like vinegar have been shown to render the stinging cells harmless, preventing them from firing more toxins into your body. (Antivenin is also available.) Or you could just do what some savvy Aussies do and wear women's pantyhose when you head out to the beach. Apparently nylon prevents the jellies from stinging since they can't detect the chemicals on your skin.

Australians have quite a bit of experience dealing with deadly creatures. Many of the world's most venomous offenders live Down Under. Along with the box jelly, which lives mainly off the coast of Northern Australia and throughout the Indo-Pacific region, the island continent lays claim to several other specimens vying for the grand prize of most venomous animal. Find out which one claims that top spot on the next page.

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Do jellyfish have the deadliest venom in the world?

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You may have been stung by a jellyfish on a trip to the beach or a dip in the ocean. But, while most jellyfish stings do little more than annoy you, the sting of the box jellyfish can literally scar you for life -- if it doesn't kill you first.

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The Tealia anemone is a good example of an Anthozoan.

These flower-like animals resemble plants, but they have a mouth
at the center of their tentacles, and a primitive digestive system.

© Jonathan Bird/ORG
For educational use only.

The phylum Cnidaria (pronounced nid-AIR-ee-ah) contains approximately 9000 living species worldwide. They are among the simplest of the so-called "higher" organisms, but are also among the most beautiful. The creatures in this phylum are radially symmetrical. This means that the parts of the body extend outward from the center like the spokes on a bicycle wheel. A common example of radial symmetry is the sea star (a member of the Echinoderm phylum) or the anemone, a Cnidarian (seen below).

The Cnidarians include the hydroids, jellyfish, anemones, and corals. All Cnidarians have tentacles with stinging cells in their tips which are used to capture and subdue prey. In fact, the phylum name "Cnidarian" literally means "stinging creature." The stinging cells are called cnidocytes and contain a structure called a nematocyst. The nematocyst is a coiled thread-like stinger. When the nematocyst is called upon to fire, the thread is uncoiled, and springs straight. The harpoon-like thread punctures through the cnidocyte wall and into the prey. Most Cnidarians also have a toxin in their stinger which helps to disable the prey. The nematocyst is fired either by the tentacle touching something, or in some cases by a nerve impulse from the animal telling it to fire.

Most Cnidarian's nematocysts are not harmful to humans, as the stinger cannot penetrate sufficiently into human skin to inflict any harm. There are some jellyfish, however, which can deliver extremely painful, and in a few cases, even fatal, stings to humans.

The Cnidarian can have one of two basic body types, polypoid or medusoid. The polypoid (POL-ip-oyd) is the configuration of corals and anemones, with the tentacles and mouth generally facing up, and the other side affixed to a substrate or connected to a colony of other creatures of the same species. In the Medusoid, the organism is essentially upside-down, with the mouth and tentacles generally pointed down. These types of Cnidarians are usually free-swimmers, like jellyfish. This is why the anemone is sometimes called an upside-down jellyfish; that's just about what it is!

The Phylum is divided up into 3 Classes, called the Hydrozoans (meaning "water-animals"), the Anthozoans (meaning "Flower-animals") and Scyphozoans (meaning "bowl-animals").

HYDROZOANS
The Hydrozoans (hydroids) and Anthozoans (anemones, corals) are mostly all bottom dwelling animals, in a polypoid shape. This means that they live attached to the bottom with their tentacles and mouth pointing up. The northern Red Anemone is a good example of an Anthozoan. Some are solitary, meaning that they live alone, but some are colonial, meaning that they live in groups, connected together with living tissue, and share food resources.

SCYPHOZOANS
The Scyphozoans (SKY-foe-zo-ans) are the animals we call jellyfishes, although since they aren't real fishes, a better word is "jellies." The jellies drift along in the water generally with the mouth and tentacles pointing down. We call this a medusoid body form. Some jellies are extremely venomous to humans. Some can even kill people with enough contact of tentacle on bare skin, but most are not that dangerous, producing only a mild rash similar to that caused by poison ivy.

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JONATHAN BIRD'S BLUE WORLD

The two different forms of a Cnidarian body.

A coral colony consists of hundreds or thousands of tiny polyps. Each polyp is an individual animal (basically a small anemone) but they live together as a group.

The Lion's Mane Jelly is a venomous Scyphozoan which can sting people with its long tentacles. Since the tentacles can hang so far down, the jelly can use these tentacles to kill fish which swim through them without ever seeing the jelly itself way up above! This is an example of a cnidarian with a medusoid shape.

The are Pink Hearted hydroids, members of the class Hydrozoa. They look like delicate plants but they are animals that sting and capture food.

This is fire coral. It has a potent sting that leaves an itchy rash on human skin. It is not technically a coral, but a kind of hydroid that encrusts other objects (including other corals).

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The Tealia anemone is a good example of an Anthozoan. These flower-like animals resemble plants, but they have a mouth at the center of their tentacles, and a primitive digestive system. © Jonathan Bird/ORG For educational use only. The phylum Cnidaria (pronounced nid-AIR-ee-ah) contains approximately 9000 living species worldwide.

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Fact sheet with photos on flora and fauna of Singapore's intertidal shores

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(Video)

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These simple creatures invented movement.

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The name Cnidaria comes from the Greek word "cnidos," which means stinging nettle. Casually touching many cnidarians will make it clear how they got their name when their nematocysts eject barbed threads tipped with poison.