Each summer, Frank Steimle gets a lot of phone calls from beachgoers about jellyfish. What do the callers want? “They want us to do something about them,” says the exasperated Steimle, a marine biologist at the National Marine Fisheries Service’s Northeast Fisheries Center in New Jersey. “Like get rid of them.”
But jellyfish are impossible to evict. Unlike sharks, you can’t exclude them from bathing areas with nets. Parts of the gelatinous creatures would simply slosh through, each piece of jellyfish puree as capable of stinging as the whole.
Killing them won’t protect you: the really notorious species can still deliver a sting after drying up on the beach.
Don’t blame the jellies. They couldn’t swim away even if they wanted to. “They move by pulsing around, but they can’t really swim,” says Sarah Jordan, who has reared hundreds of them for Boston’s New England Aquarium.
Jellyfish are mostly deep-sea animals. Their movements are largely at the mercy of ocean currents, so coming to shore isn’t their idea. In fact, jellyfish probably have very few ideas, since they don’t have brains. They don’t even have heads.
For a creature so feared, jellies are rather helpless. They have no organs. They have no blood. They have no eyes. They regenerate lost body parts easily because there’s so little to regenerate—they’re 95 percent water. “Jell-O with a mouth,” as one scientist puts it.
Still, what little they do have has done the job quite nicely for the past 500 million years: a simple nerve network and primitive muscles allow them to pulse through the water. The bell-shaped mantle is fringed with tentacles, and a cluster of longer structures hangs down from the center like the handle of an umbrella. These, believe it or not, are the jellyfish’s lips.
Most portions of the jellyfish, but particularly the tentacles, are endowed with stinging, harpoonlike cells that burst out of the critter whenever it brushes against something. The tentacles of some types of jellyfish are designed to stun and capture prey so small that human skin is too thick to even feel the sting. But several jellyfish do sting people, and generally people are against this. Public fear is so great that, in 1966, Congress passed the Jellyfish Control Act, appropriating $5 million to find ways to “control and eliminate jellyfish and other such pests in our coastal waters.”
Good thing the money ran out. As it so happens, the oceans’ more than two thousand species of jelly-like, see-through creatures may be some of the most important players in the health of the world’s waters. They provide food for some species (sea turtles and giant ocean sunfish eat them almost exclusively). They offer shelter to others (young cod and haddock, among others, hide behind jellies’ curtain of stinging tentacles). And their appetites regulate the number of their prey species, from tiny plankton to other jellyfish and jellyfish look-alikes.
The jellyfish you are most likely to bump into while you’re swimming near the shore won’t hurt you. Among the commonest species is the moon jelly, a milky white animal with a bold cloverleaf design on its top, a creature so benign you can hold it in your hand. (While you’re examining it, note the color of the cloverleaf: if white, you’ve got a female; if pink, a male.)
In fact, jellyfish and their gelatinous relatives do us far more good than harm. They’re even helping researchers investigate basic questions about biology.
“People are very confused about jellyfish,” says Wendy Lull, director of New Hampshire’s Seacoast Science Center. No wonder. Many jellyfish aren’t actually jellyfish after all. The commonest gelatinous animals in the ocean—the small glistening globs you find washed up on the beach—are not jellyfish but ctenophores (pronounced TEE-no-fors), sometimes also called comb jellies. They don’t have stinging cells. They use sticky drool to capture fish fry, invertebrates, and other ctenophores. They don’t move by pulsing, but by wiggling hairlike structures called cilia, which look like the teeth of a comb. (Ctenophores have the largest cilia of any creatures in the world, which makes them of great interest to Sidney Tamm; his studies at the Marine Biological Laboratory in Massachusetts may help explain how cilia keep lungs clear, propel sperm, and perform many other critical functions.)
But ctenophores’ most spectacular trick—as you’ll see if you swim on a night when they mass near the shore—is that when jostled, they glow.
The flashes may scare off predators; no one’s sure. But at least we know how, if not why, ctenophores and certain other jellyfish glow: Andrew Miller, another scientist at Marine Biological Laboratory, explains that ctenophores possess a protein, aequorin, in special capsules in the mantle. When the animals release calcium into the capsules, a glow results.
Miller is using aequorin in the laboratory as a biological marker, allowing him to watch how calcium moves within cells in order to understand basic biological processes. But West Coast Native American tribes recognized this property long ago. They dried ctenophores and certain jellyfish to a powder, and applied it to their bodies during ceremonial nighttime dances. As the dancers sweated with exertion, the calcium in their perspiration would react with the protein, causing the dancers to glow green in the firelight.
If the most beautiful jellyfish isn’t really a jellyfish, neither, technically, is the most dreaded. The Portuguese man-of-war, mainly a tropical, deep-sea species, is actually a creature called a hydrozoan. This powerful stinger is easily recognized: first you’ll spot its brilliant blue, pink, or purple sail, allowing it to ride the wind. Below the sail is the creature’s gas-filled float, and beneath it, the forty- to fifty-foot-long tentacles. Each man-of-war is actually a colony of individuals, some responsible for capturing food, some for reproduction, others for eating.
One reason jellyfish and their relatives are so confusing is that they are difficult to study. They start out virtually invisible and end up see-through. Young jellyfish-to-be spend the winter as shy polyps, sea-anemone-like blobs less than a quarter-inch long, often hiding in the cracks on jetty pilings. Then, depending on the species, they may go through several other stages, during which they may look like a stack of tiny pancakes made of Jell-O, or floating stars, until finally they turn into proper-looking jellyfish.
Events during any of these stages might affect jellyfish numbers and whether or not they are coming to a beach near you, explains Barbara Sullivan, a marine research scientist at the University of Rhode Island. She’s investigating the movements and foods of the lion’s mane jellyfish, the stinging, rust-colored beings who alarmed East Coast beachgoers with their sudden “blooms” in 1992, 1987, and 1986. And they’re not the only jellies that “bloom.” Sometimes, around the Chesapeake, the stinging nettle infests bays and estuaries so thickly it clogs fishermen’s nets.
Even during bloom years, we have it pretty easy in temperate North America. Australia has the sea wasp, whose dangerous sting is so painful its victims think they’ve been bitten hy sharks. And in the Arctic, there’s the lion’s mane again, but this time it’s a Hitchcock version of The Blob: there, the animal’s mantle grows up to eight feet across, and its tentacles stretch two hundred feet. Frank Steimle is glad his callers haven’t heard about those.
What should you do about close encounters of the gelatinous kind? Experts advise that if you see a jellyfish, unless you have a positive ID on a moon jelly or a ctenophore, assume it can sting you—even if it’s dried up and dead on the beach. Don’t touch it.
If a jellyfish is floating beside you in the water, don’t panic. Just swim away calmly. (If you thrash off in a hurry, you might create waves that move the floating tentacles toward you.)
Like bee stings, jellyfish stings can produce violent reactions in allergic people, requiring emergency room treatment. But for most folks, these remedies will suffice:
• Flush the area with seawater—not fresh water. Fresh water will make the sting more painful.
• Apply a paste of meat tenderizer mixed in seawater (or vinegar). It dissolves the poison by breaking down its proteins.
• Don’t try to remove the stingers; they’re too small You’ll only further irritate the area. But sometimes a piece of tentacle will stick to you like seaweed. Carefully peel it off, using a towel to shield your hands.