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Saw this in our local paper: The Nashua Telegraph
Local jellyfish nary a danger to swimmers
By ALASDAIR STEWART, Telegraph Staff
Thousands of jellyfish swarmed Naticook Lake this week.
No need to head for the hills, though. The invertebrates found in Merrimack bear little resemblance to a man-of-war.
Rather than stinging swimmers into submission, the quarter- to half-dollar-size animals prey mostly on microscopic critters.
Freshwater jellyfish are known to hang their hats in most of the state’s lakes. They are not often seen, but have been reported several times in Naticook Lake and at about a dozen other sites in New Hampshire, including Lake Massabesic and Squam Lake.
Most other states are home to the species,
Craspedacusta sowerbii, which also lives in other countries of the Northern Hemisphere. The species was discovered in England in 1880 and in the United States in 1908.
Around here, August and September comprise the prime jellyfish-sighting season. Warm weather is believed to be a reason for sudden appearances of jellyfish, but although the species has been researched, it remains mysterious.
Jellyfish live in many bodies of fresh water, usually maintaining a low profile as polyps at the lake bottom. Jellies, like frogs and butterflies, are metamorphic, meaning they undergo radical changes in appearance during their lives.
Freshwater jellyfish are not known to migrate under their own power. Scientists opine that jellies may hitchhike, perhaps on the feet of ducks and other waterfowl.
Freshwater jellies inhabit nearly all of the state’s 800 to 1,000 lakes, according to Ken Warren of the state Department of Environmental Services.
However, the competition for weirdest lake inhabitant is stiff, Warren said. Jellyfish might be unexpected, but another organism, the bryozoan, probably takes the cake.
Colonies of the tentacled animals sometimes form on tree branches hanging into the water and “look like some space alien brain,” Warren said. Bryozoans, like freshwater jellyfish, do not pose a hazard to people.
Scientists classify freshwater jellyfish separately from “real” jellyfish, such as the more famous man-of-war and Australian box jelly. The distinction is worth mulling over, but maybe not for hours on end.
All jellyfish belong to the same phylum, Cnidaria (from the Greek word for “nettle”), a group that includes corals, anemones, jellyfish and many other species. From a taxonomic perspective, the jellyfish you see at the beach are as closely related to freshwater jellies as to the man-of-war.
Taxonomy – or maybe semantics – aside, freshwater and marine jellyfish share a number of traits. All sting, all are carnivorous and all, of course, live in water. All jellies use a sort of jet propulsion to get around, and though they have no brains and apparently can’t see, they can navigate and detect prey.
Contrary to scattered complaints, most scientists say freshwater jellyfish do not sting people, unlike some of their cousins. A guide to the coastal dangers of Australia, for example, says of the Australian box jelly, “You have virtually no chance of surviving the venomous sting.”
Local jellyfish nary a danger to swimmers
By ALASDAIR STEWART, Telegraph Staff
Thousands of jellyfish swarmed Naticook Lake this week.
No need to head for the hills, though. The invertebrates found in Merrimack bear little resemblance to a man-of-war.
Rather than stinging swimmers into submission, the quarter- to half-dollar-size animals prey mostly on microscopic critters.
Freshwater jellyfish are known to hang their hats in most of the state’s lakes. They are not often seen, but have been reported several times in Naticook Lake and at about a dozen other sites in New Hampshire, including Lake Massabesic and Squam Lake.
Most other states are home to the species,
Craspedacusta sowerbii, which also lives in other countries of the Northern Hemisphere. The species was discovered in England in 1880 and in the United States in 1908.
Around here, August and September comprise the prime jellyfish-sighting season. Warm weather is believed to be a reason for sudden appearances of jellyfish, but although the species has been researched, it remains mysterious.
Jellyfish live in many bodies of fresh water, usually maintaining a low profile as polyps at the lake bottom. Jellies, like frogs and butterflies, are metamorphic, meaning they undergo radical changes in appearance during their lives.
Freshwater jellyfish are not known to migrate under their own power. Scientists opine that jellies may hitchhike, perhaps on the feet of ducks and other waterfowl.
Freshwater jellies inhabit nearly all of the state’s 800 to 1,000 lakes, according to Ken Warren of the state Department of Environmental Services.
However, the competition for weirdest lake inhabitant is stiff, Warren said. Jellyfish might be unexpected, but another organism, the bryozoan, probably takes the cake.
Colonies of the tentacled animals sometimes form on tree branches hanging into the water and “look like some space alien brain,” Warren said. Bryozoans, like freshwater jellyfish, do not pose a hazard to people.
Scientists classify freshwater jellyfish separately from “real” jellyfish, such as the more famous man-of-war and Australian box jelly. The distinction is worth mulling over, but maybe not for hours on end.
All jellyfish belong to the same phylum, Cnidaria (from the Greek word for “nettle”), a group that includes corals, anemones, jellyfish and many other species. From a taxonomic perspective, the jellyfish you see at the beach are as closely related to freshwater jellies as to the man-of-war.
Taxonomy – or maybe semantics – aside, freshwater and marine jellyfish share a number of traits. All sting, all are carnivorous and all, of course, live in water. All jellies use a sort of jet propulsion to get around, and though they have no brains and apparently can’t see, they can navigate and detect prey.
Contrary to scattered complaints, most scientists say freshwater jellyfish do not sting people, unlike some of their cousins. A guide to the coastal dangers of Australia, for example, says of the Australian box jelly, “You have virtually no chance of surviving the venomous sting.”
