Small, jellylike creatures on Outer Banks pose no danger

By CHERYL JOHNSTON, The Virginian-Pilot
© June 26, 2004

Swimmers and waders enticed by the warm water on the Outer Banks in recent weeks have sometimes found an ocean more like pudding or Jell-O than saltwater. Piles of small, bubbly jelly-like organisms have been washing ashore since late May, leaving lifeguards and the North Carolina Aquarium on Roanoke Island to field numerous questions from beachgoers who want to know what they are and whether they’re dangerous.

Unofficial explanations have been almost as numerous as the jelly chains on the beach – shark eggs, fish eggs, maybe baby jellies.

Those answers are all wrong, said Heather Bates, an aquarist at the North Carolina Aquarium on Roanoke Island.

Someone brought her a bucketful, and she quickly identified them as salps. She then went to Pea Island to swim among the sticky chains herself. Salps neither sting nor bite – they’re harmless, Bates reassures callers.

They’ve been spotted at least as far north as Corolla and as far south as Buxton. There are several species of salps, and Bates said she thinks this particular visitor is the species thalia democratica.

They are transparent, and a blue spot can usually be seen at one end. Depending on the stage of reproduction, two armlike or hornlike projections can be seen. They are small – no longer than an inch – and oval-shaped. And they often form chains that can be several meters long.

Richard Harbison, a marine biologist at the Woods Hole Oceanographic Institution on Cape Cod, said he has seen large blooms of salps several times along the coasts of Massachusetts and Florida.

Without being in North Carolina to see the salps for himself, Harbison’s guess was also thalia democratica.

“It’s very common for them to form huge blooms,” Harbison said, adding that they are prevalent in the Georgia Bight, a wide pocket of water between the coast of Georgia and the Gulf Stream.

“It’s likely that there are huge masses of them in the Georgia Bight right now, and the current and winds right now are bringing huge masses near shore,” Harbison said. “Most salps are found out in the ocean where people never see them.

“You’re not going to see them until there’s onshore winds, onshore currents,” he added.

Both Bates and Terri Hathoway, a marine education specialist for Sea Grant on Roanoke Island, have noticed that people are confusing the salps with two other jellylike organisms that are also on the shore right now – naked sea butterflies and comb jellies.

Bates said naked sea butterflies are a little longer and skinnier. They look like they have wings with red or salmon-colored tips. And they are black on the bottom. They are called “naked” because they are mollusks without a shell.

Hathoway said they are also rarely found on the beaches.

Bates described comb jellies as larger than the other two organisms, with rainbow colors streaked through their bodies. Salps are not jellyfish at all.

“They’re our closest-related relative among invertebrates,” said William W. Kirby-Smith, a marine ecologist at the Duke University Marine Laboratory near Beaufort.

Kirby-Smith said that in their larval stage, they have a hollow nerve cord like vertebrates. They also have a notochord, which is a supporting rod that runs down their back, but it does not form into a vertebral column that in humans becomes the inner vertebral discs.

“They have muscles and nerves and brains,” Harbison said. “They’re very complex animals.

“With a microscope, you can see an eye around the brain. The eye collects light but does not form an image.”

Harbison calls their means of reproducing “peculiar” because they alternate between sexual and asexual reproduction. The females are fertilized and produce an embryo. When the embryo is released, it buds an aggregate that is female. The “mother” female then grows testes, becomes male and releases sperm, which fertilizes the aggregate.

Harbison said in the sexual stage, the female salps with embryos are linked together. Their entire generation cycle can be less than two days.

Salps have visited the Outer Banks before. Hathoway, who has been on the Outer Banks for 18 years, can recall three or four visits. The last was in June 2001. But none of the previous blooms has been as large as what people are describing to Hathoway this time.

Depending on the wind and water, they are coming and going on the beaches. Most of the lifeguards are reporting seeing fewer this week than two weeks ago.

If people are swimming with salps, they know it.

“Everybody says they’re kind of gross, and they get stuck in people’s hair,” said Mike Murray, a lifeguard supervisor in Nags Head.

When piles of them are left on the beaches, the squishy salps pose a challenge for ATVs patrolling the beaches. “They would get all caught up in the gears, and it took an hour to clean it out,” Murray said.

Shaun Buen, the ocean rescue supervisor in Corolla, says his staff has trained, swum and run in them. They were particularly abundant at the northern end of the beach in May and the first week of June, Buen said.

“When they would wash up and dry up, they would smell and create this almost cardboard-like film over the sand,” Buen said.

He added that he had thought they were gone last weekend until he saw an ocean full of them in Nags Head on Sunday. Then they were back on his beaches in Corolla later this week.

Harbison said salps do have a purpose. They are food for a variety of fish, as well as for sea turtles and jellyfish.

Salps are filter feeders that trap microscopic plankton in a mucous net suspended in their bodies. And they are seen on the surface only if the water is calm.

Harbison says they can’t survive this close to shore for long.

“They like it where there’s not much turbulence,” Harbison said. “The ones that are on the beach are dead ducks.”

Reach Cheryl Johnston at (252) 441-1625 or cheryl.johnston@pilotonline.com

Media contact: Tim Lucas, 919/613-8084 or tdlucas@duke.edu