Dead jellyfish on Hilton Head’s beaches explained

The other day I was enjoying a soothing beach walk at sunset when I stumbled on what only could be described as a jellyfish graveyard on Hilton Head Island’s South Beach.

It was a disturbing and kind of disgusting sight — hundreds of lifeless jelly figures and detached gooey limbs cluttered the shore, making it almost impossible not to step on one.

As a fairly new Islander who moved to the area almost a year ago, I didn’t know what to make of this. To me, it looked like a poison of some sort killed these jelly fellows. I’ve seen the occasional few dead jellyfish along the beach, but nothing that looked like a mass murder.

So I did some research and asked a couple experts. Here’s what I’ve found out:

This happens a lot.

Carlos Chacon, manager of natural history at the Coastal Discovery Museum, said the Hilton Head coast normally sees large numbers of jellyfish washing ashore during the spring and early summer. However, incidents can happen at other times of the year that cause several hundred jellyfish to appear on shore at one time.

What causes large numbers of jellyfish to wash up on shore at a time?

Jellyfish tend to travel in groups, called blooms, and sometimes rough winds, swells and currents send them to shore at once. Cooler water temperatures also contribute to mass jellyfish deaths.

“Jellyfish are organisms that swim with the current. They often get pushed to shore as a group,” Blaine Griffen, a marine biologist at the University of South Carolina, said. “Sometimes, it’s the current, and some of them are just killed by annual population cycles.”

Jellyfish are mostly made of water, so they die quickly after washing up on shore.

Jellyfish can sting you after they are dead.

The good news is that the most popular jellyfish in South Carolina waters is the cannonball jelly, which Chacon said is not harmful to humans, dead or alive. Some people even pick them up and play with them.

“They can be fun to play with,” he said.

Cannonball jellyfish look like mushrooms, and loose their color soon after they wash up on shore.

The bad news is that other dead jellyfish known to swim off the Carolinas can sting you when they’re dead, like the Portuguese man-of-war, which is blue or purple in color and looks like a blown-up plastic bag.

So in general, don’t touch a dead jellyfish if you don’t know what kind it is.

How can you tell if a jellyfish is dead?

In general, if the jellyfish has lost its typical round shape and is sort of flat, it is dead, Chacon said. However, if it is still round and freshly washed ashore, it might be alive.

Nature takes care of these dead jellies.

Don’t worry, no one has to clean up dead jelly bodies on the beach.

“They will get eaten by seagulls, crabs and other scavengers, and whatever is left of it will eventually decompose on the beach.” Chacon said.

This story was originally published January 26, 2017 at 10:58 PM with the headline "Dead jellyfish on Hilton Head’s beaches explained."