Swarms of sea wasps to taper off in the fall

by Sam Wilson
Wednesday, September 11, 2013

Supplied photo courtesy of Julia Tillery 

The number of Chiropsalmus quadrumanus, more commonly known as the sea wasp because of its painful sting, will taper off at the end of this month.

Through the end of September, swarms of jellyfish with the ability to deliver a nasty sting will be completing their peak blooming season off the coast of southeastern North Carolina.

Chiropsalmus quadrumanus, more commonly known as the sea wasp, is a softball-sized type of box jellyfish with the same venom as its more infamous north Australian relative, which carries a reputation for stings that can induce cardiac arrest within minutes. However, Julia Tillery, a Wrightsville Beach resident and graduate of the University of North Carolina Wilmington’s Master’s of Environmental Science program, explained in a Sept. 3 interview that the local sea wasp’s sting is far less potent.

“It’s called the sea wasp, because if you think about all the winged stingers, the wasp is the one that hurts the most, and the box jelly is the jellyfish that has the worst sting,” Tillery said, calling it, “more of an annoying kind of hurt.”

Her work on jellyfish was conducted as a part of the research being led by University of North Carolina Wilmington marine biology professor Dr. Richard Satterlie. A neurobiologist, Satterlie, has studied the nervous systems of box jellyfish for decades, focusing on the primitive muscular system that allows them to swim, unlike their free-floating cousins that are more frequently found washed ashore.

“We’re looking at how these jellyfish move, and how they steer,” Satterlie said. “They can turn 90 degrees in just two or three contractions, they avoid obstacles and they can move toward prey. They also have image-forming eyes ... [that] can tell light from dark and form crude images.”

The implications of this new research could be significant, Tillery said.

“In terms of evolution, they’ve been around for a long time,” she said. “It’s very basic physiology in terms of how things evolve and develop. … We know that in studying ecology, it helps us to know how the food chain works and how everything is related to one another.”

Navigating the Center for Marine Science laboratory complex, Satterlie entered a dimly-lit room filled with aquariums and stacks of marine lab equipment including a series of tanks devoted to propagating jellyfish.

“These little whitish things are the polyps of two species of box jellyfish,” Satterlie said, pointing to a 20-gallon saltwater tank, empty except for the pebble-sized polyps. 

“We’ve been playing around with ways to get those to metamorphose into adult jellyfish,” he said.

Jellyfish belong to a phylum in the animal kingdom known as Cnidaria, comprising more than 9,000 distinct species, including corals and sea anemones. One key characteristic of jellyfish is the presence of the polyp stage in the reproductive cycle. Bound to the ocean floor, the polyps bud from the fledgling jellyfish.

Like all jellyfish, box jellies are 99 percent water. Given the right ocean conditions, they can grow rapidly, quickly reaching reproductive age, Satterlie said. Coupled with their ability to tolerate oxygen-starved -environments that repel many natural predators, box jellyfish blooms can be enormous. Their pesky stings aside, Satterlie said that could have grave implications for one of the North Carolina coast’s oldest industries.

“They are predators, and the box jelly in particular is going to eat small fish and small shrimp, animals that are commercially valuable,” he said. “So if you have a big enough bloom of these guys, they can potentially wipe out the shrimp population in a localized area and the fishermen will have to go somewhere else.”

Satterlie said many shrimpers have confirmed this potential with reports of significant -jellyfish findings in their shrimp catches.

Dr. Satterlie and his research team have made significant findings, but he stressed much work remains to be done. For one, the number of box jellyfish in the area and the ideal conditions required for their blooms are not well understood, making it all but impossible to predict with precision when and where blooms will occur. 

Tillery said that during her second summer, the sampling trawls would bring in more than 100 jellyfish per trip. The next year, however, she said they had only found five after multiple trips leading up to the usual reproductive peak, from late summer to early fall.

“I do suspect there may be local populations of polyps, because they overwinter. The polyps need the cold and then they need the warming up to metamorphose into adults,” Satterlie said.

But locating the tiny, sand-colored dots on the sandy ocean floor is not an easy task.

“We’re trying to find a needle in a haystack,” he said.

email sam@luminanews.com

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