Jellyfish Stings: The Longer the Nastier, Say Experts

Any beachgoer, snorkeler, or diver can tell you that while the ghostly forms of jellyfish are beautiful to behold, you don't want to go anywhere near them. It's not uncommon for jellyfish stings to cause painful, paralyzing, or even lethal reactions, and it's often very difficult to tell which jellies are harmful. That's why researchers have looked into a new way to assess these bizarre creatures: by the length of their stingers.

According to a study recently published in the journal PLOS One, the longer a jellyfish can extend its stinger-tipped tentacles, the more likely it's sting will be deadly.

And frankly, that just seems unfair. Not only can these alien-like animals of the deep inject potentially deadly venom into a person in just about 1 microsecond, according to the National Science Foundation (NSF), but they can also do this stinging at incredibly long range.

Just how long? The lions' mane jellyfish (Cyanea capillata), which the NSF describes as a "giant formation resembling [a] horrifying hairball," has tentacles that extend up to 100 feet - just long enough to reach the top of a 10-story building! These lengthy 'arms' also happen to be lined with tiny nematocysts that discharge tiny toxic tubules into prey's skin. Contact with one often results in very painful rash-like reactions and usually calls for medical attention. (Scroll to read on...)

In fact, the broken remains of a single dead lion's mane managed to sting a whopping 150 people all at once at Wallis Sands State Park, New Hampshire, five years ago - a testament to the stinging power of these unusual creatures.

However, according to researcher Ryuji Kitanani, who led the sting study, it's not actually long tentacles that are the only tell of a bad sting. The lion's mane sting is actually quite tame compared to others. The notorious sea-wasp box jellyfish (Chironex flecker), for instance, kills an estimated 40 people in Philippine waters every year. It is, according to most official records, the most venomous animal in the world, and yet its own tentacles are ten times shorter than lion's mane arms.

Instead, lengthy tentacles are often a result of having long sting tubules. Kitanani, and his colleagues at Tokyo University of Marine Science and Technology considered the fact that the nerve cells responsible for picking up intense pain sit about 100 to 200 micrometers (µm) beneath human skin. It would stand to reason then, that harmful tubules would extend past that, contributing to longer tentacles overall for potentially deadly jellies. (Scroll to read on...)

After an extensive survey of harmful and harmless species, the researchers concluded that this usually holds true. The study details how deadly species like the habu-kurage box jelly (Chironex yamaguchii) are equipped with 334 µm long tubules while the relatively harmless moon jelly (Aurelia aurita) boasts stingers well under 100 micrometers long.

"Harmful species tended to have longer tubules," Kitanani reiterated.

Still, he and his colleagues are careful to point out that the longest tubule won't always be the deadliest. Carybdea brevipedalia, a species commonly found along coastal regions, proved to have the longest tubules surveyed, with a max length of about 1524 micrometers. Their sting however, is rarely deadly, and only produces a rash-like reaction similar to that of a Lion's mane's. What makes C. yamaguchii more deadly, they believe, is a fatal balance between long arms and long stings, where more tubules are likely to pierce a person in contact with a long arm.

The take away, then, is simple. If you see a jelly with long and threatening arms, it might be time to get out of the water.

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