2017-09-14 / Nature

Jellyfish Undulate into Narragansett Bay

By Charles Avenengo


A Portuguese Man O' War is a colony of highly modified single animals. Photo taken near Kettlebottom Rock in Jamestown. (Photo by Suzanne Reed) A Portuguese Man O' War is a colony of highly modified single animals. Photo taken near Kettlebottom Rock in Jamestown. (Photo by Suzanne Reed) Narragansett Bay’s average annual temperature is two degrees warmer than in 1960. As a result, there have been many changes, including an increase in jellyfish.

Jellyfish, or “jellies,” are otherworldly planktonic drifters. With their bizarre shapes, it is a wonder they haven’t been featured in more science fiction horror movies. As they pulsate through life, flowing along with the currents and tides, their presence is often marked by uncountable swarms of them.

The villain of the group is the notorious Portuguese Man O’ War. Normally associated with tropical and offshore waters, they can also be found locally. Over the years, beach walkers have occasionally found them washed ashore, usually immediately after a tropical storm. Offshore mariners south of Cape Cod have encountered them in warm-water pockets, with more frequent sightings the closer the vessel is to the Gulf Stream.

This year, however, has been the most active on record for the infamous jellyfish. They have been seen in coastal waters throughout Rhode Island and Massachusetts, with Man O’ Wars even found washed ashore on Easton’s Beach.

During this invasion, at least three children have been stung by Man O’ Wars in Westerly and Charlestown. In Westport, Mass., a man was hospitalized after being stung by two Man O’ Wars.

Despite painful encounters, there weren’t any fatalities in the United States as a result of the Portuguese Man O’ War until 1987, on Florida’s Atlantic Coast when a sting led to the death of a man from respiratory arrest and cardiovascular collapse.

This year’s invasion is due to a series of tropical storms in July that produced northern winds for about 10 days and pushed the warm-water dwellers closer to shore. Once there, the Southern drift visitors encountered the locally warmer water that enabled them to sustain themselves.

The larger Lion’s Mane jelly is sometimes confused for a Portuguese Man O’ War. Considered part of the local marine fauna, many bathers occasionally feel their stings. Found along the Eastern Seaboard, they grow larger the further north they move. While in Rhode Island, the gelatinous umbrella of a Lion’s Mane occasionally may reach one foot in diameter, with the bells of some giants further north reaching eight feet across. Even more alarming is their tentacle length. One specimen that washed ashore in Massachusetts Bay in 1870 had tentacles measured at 120 feet.

Lion’s Mane jellies have been part of English Literature lore. In one of his final cases, “The Adventure of the Lion’s Mane,” Sherlock Holmes proved the deaths of a schoolmaster and his dog was not the result of a lovers’ quarrel, but rather a Lion’s Mane lurking in a tide pool. Although perhaps a fantastical plot, Holmes nevertheless heroically dispatched it with a stone.

While other groups of animals fall into easily recognizable categories because of their variety in form and the difficulty in studying them, biologists have a hard time classifying jellies. Collectively, they are generally referred to as “Coelenterates,” a group of taxa that also encompasses corals and sea anemones. However, most forms of jellies are gelatinous and fragile, and have radial symmetry that looks like spokes around a wheel.

There is currently a large group of jellies, called “Ctenophores” or “Comb” jellies, in the bay. They are easily visible if you focus on the water column between the bottom and the surface. They are up to four inches long, and are now found here year round due to the increase in the water temperature.

Comb jellies don’t sting, and they are responsible for the bioluminescence flashes seen in the water at night. Also, when viewed by day under good sunlight, they are iridescent. While they are the principal food for leatherback and other fish, Comb jellies can mean death for anything in the way of the voracious predator’s sticky tentacles. When they were accidentally introduced by a container ship into the Black Sea, local fish stocks were nearly depleted as the Comb jellies worked their way through the eggs and larvae of the helpless fish.

Close inspection of the water reveals that even smaller forms of jellies are present in abundance. Because of their transparency, they can initially be difficult to see. However, once locked onto, a strange ethereal universe of planktonic hydromedusae is revealed. With names like “salps, sea-gooseberries, sea-arrows, oikopleura,” and “Venus girdles,” they are as strange as their labels. Some, like Stephanomia cara, although abundant because of their indescribable fantastic forms, don’t even have common names.

Regardless of the name, they are here, silently drifting into virtually every nook and cranny of the bay. And with the warmer waters, we will have to contend with more and more jellies.

Jellyfish Sting First Aid

If a person is stung by a jellyfish:

. Get the person out of the water.

. Call 911 if there are signs of an allergic reaction or the sting covers more than half an arm or leg. For severe reactions, affected persons may be hospitalized.

. Wash the sting with seawater to deactivate stinging cells. Tentacles can be removed by scraping them off with a credit card or another plastic object. Unlike in the Pacific, the use of vinegar is discouraged in the North Atlantic as it might make the symptoms worse.

. For a Portuguese Man O’ War sting, immerse the affected area in hot water for at least 20 minutes.

. To treat discomfort, use mild hydrocortisone creams or oral antihistamine to relieve itching and swelling. For less severe stings, use ice packs or over-the- counter pain relievers for the welts.

. Clean open sores daily and apply antibiotic ointments. Bandage if necessary.

Naturalist Charles Avenengo has been chasing Aquidneck Island wildlife for more than 40 years.

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