NEWBURYPORT — Warmer-than-usual temperatures might be the reason for another unexpected visitor to the river this summer, and just about everybody on the Merrimack has noted the comings and goings of the translucent creatures.
Jellyfish have been swept into the Merrimack by incoming tides for the past few weeks, where there is unusually warm water upriver. It's the first time many have seen them in the river, and it's been much discussed along the waterfront.
"These were white jellyfish that I've never seen in this area," said longtime tuna fisherman Joey Jancewicz, "and they were all dead."
Ranging in size from a tennis ball to a basketball, according to the maintenance crew of Freedom Boat Club, the jellyfish have been caught up in the docks where Freedom Boat Club's members tie up.
"We see them constantly," Zack Ames said. "They're see-through, and they're big blobs, and they look like something you'd get blowing bubbles. You look at them and think they'd be soft, but they're hard."
"We've seen them the size of basketballs," said fellow Freedom Boat Club staffer John Jamieson, who, along with Ames, has picked the little ones out of the water and held them in his hand without being stung.
Like a moon jellyfish, they have no tentacles and offer no unpleasant surprises to inquisitive landlubbers, as Kate Yeomans has demonstrated to several classes of children participating in her and husband Rob Yeomans' boat camp this summer.
"The jellyfish that we've seen are solid — probably the size of a dinner plate," Kate Yeomans said. "They had no tentacles. Last fall, we saw some jellyfish, but they were more like true jellyfish. This one is just a solid mass — it feels rubbery."
The jellyfish are in no way similar to the dead lion's mane jellyfish that wreaked havoc on a Rye, N.H., beach 10 miles north of here earlier this week, stinging upward of 150 children after it began breaking apart.
"(Lion's mane jellies) are really not an estuary or coastal species," said Adam Lee of the Joppa Flats Audubon Education Center. "What they like to eat is pelagic ocean fish. You very infrequently see them along the coastline. For a jellyfish, they're strong swimmers, but when they die they usually wash up on shore."
Lee said the jellyfish being described in local waters sound like moon jellyfish, a coastal- and estuary-based species that, like other jellyfish, are reaching sexual maturity and are appearing in area waters.
"The reason we're probably seeing them in the river is that jellyfish aren't terribly good swimmers, and since there are slack tides coming in and out, sometimes they get sucked up into the river," Lee said. "The temperature that they really like to exist at is 77 degrees, and the water is getting a little warmer — especially in the river."
Moon jellyfish are not dangerous at all, Lee said.
"Their nematocysts aren't strong enough to sting anybody," he said, though he advises people not to pick them up.
"They are completely gelatinous — they'll fall apart," he said, adding he was somewhat perplexed by reports that they seemed hard to the touch rather than soft. While in death the moon jellyfish would tend to lose some of its water content, Lee said he wouldn't exactly describe them as hard.
"When a jellyfish dies, they don't harden," he said.
But they do have muscles in their "bell," which have elasticity, he said. And just because they're not moving doesn't mean the fish are dead.
"One way you tell a jellyfish is alive is having it move — if its bell is undulating," he said. "They do rest — they're not perpetually in motion. If you see one I suggest you let it be."
