Jellyfish putting sting in midsummer on bay


On The Water

Watersports in Anne Arundel County

July 20, 2005|By Annie Linskey | Annie Linskey,SUN STAFF

Now, just when a cooling plunge in the Chesapeake Bay seems most enticing, there's a nettlesome catch: the mid-July onslaught of stinging jellyfish.

Technically, of course, they are not fish but marine invertebrates known as cnidarians - invertebrates that can sting. They are closely related to coral. "We call them jellies," said Richard A. Lerner, a curator with the National Aquarium in Baltimore.

They come in various shapes and sizes - but there are three common jellies that haunt the Chesapeake.

The least irritating are the comb jellies. These creatures are fist-sized and completely transparent. Contrary to popular belief, they do sting, said Lerner, but most humans can hardly detect their mild touch.

The bay also is home to the moon jelly - a creature that "stings lightly," Lerner said. They are about the size of a plate and have a round, flattish bell and short tentacles.

The real problem - for humans - is sea nettles. The National Oceanic and Atmospheric Administration's Web site calls these creatures a "biotic nuisance." NOAA creates maps every Friday predicting where the sea nettles are likely to be in the Chesapeake.

And swimmers and water-skiers near the mouth of the Chesapeake are now likely to spot them floating with the currents. They look a bit like a woman's fancy hat.

Sea nettles eat plankton, algae and small fish that flourish when the water temperature rises, Lerner said. "Their food sources increased, so their numbers are rising," he said.

In addition, the relatively calm bay waters guarantee that Chesapeake jellies survive longer than they would in rougher waters - several months rather than weeks or days.

What exactly happens when the sea nettle stings?

"Their tentacles are full of these little, tiny curled barbs," Lerner said. "When you touch them, and they sense you, they shoot out barbs, and the barb sticks in your skin."

Barbs can only sting once, Lerner said. But the tentacles are packed with thousands of them.

Jellies use these barbed tentacles to capture food. When jellies happen upon bite-sized fare, their "barbs hold into it and they retract their tentacles and pull it into their mouths."

Sea nettles have tentacles that reach a couple of feet into the water. They do tangle with human swimmers - but we get stung because they have little control over what hits their tentacles, Lerner said.

For most humans, a brush with a sea nettle is hardly a major problem. Usually people will feel a burning sensation that goes away quickly. As with bee stings, however, some can have much more severe reactions.

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.