Untamed Lowcountry

Thousands of dead jellyfish wash up on a Hilton Head beach. Here’s what you need to know

Hilton Head islanders are used to seeing a few dead jellyfish cluttering the shoreline, but the scene on South Beach Tuesday appeared to be a jellyfish catastrophe when thousands of small cannonball jellyfish washed up on the shore stretching more than a mile.

Looking in both directions from Tower Beach in Sea Pines, dead jellyfish littered the tide line.

We’ve written about these “jellyfish graveyard” incidents before on Hilton Head, particularly in the spring and summer months.

It can be a disturbing and kind of disgusting sight. And the smell leaves a lot to be desired, too.

What exactly is going on in the ocean that wipes out masses of jellyfish at one time?

We reached out to a couple of experts to find out.

What causes this?

For more than a mile, cannonball jellyfish cluttered the shore in Sea Pines on Hilton Head Island.

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, previously told The Island Packet. “Sometimes, it’s the current, and some of them are just killed by annual population cycles.”

Also, it’s “jellyfish bloom time in the North Atlantic,” the Marine Biology Association of the UK explained to us on Twitter. “If you’ve had onshore winds in the last few days, swarms of jellies can wash up.”

Jellyfish are mostly made of water, so they die quickly after washing up on shore. They’re cold-blooded animals and can lose mobility when water temperatures are below normal.

This happens a lot.

Carlos Chacon, manager of natural history at the Coastal Discovery Museum, previously told The Island Packet that Hilton Head’s coast normally sees large numbers of jellyfish washing ashore during the spring and early summer.

However, weather-related incidents can happen at other times of the year that cause several hundred jellyfish to appear on shore at one time.

It also isn’t unique to Hilton Head. Hundreds of jellyfish washed up on Sullivan’s Island near Charleston a few weeks ago, WSOC reported.

Cannonball jellyfish are not harmful to humans, according to experts. Mandy Matney photo The Island Packet

The good news is that the most popular jellyfish in South Carolina waters is the cannonball jelly (seen above), which Chacon said is not harmful to humans, dead or alive.

In Asia, it’s common to see these types of jellyfish commercially harvested for human consumption. Cannonball jellyfish are high in protein and packed with nutrition.

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

Some jellyfish can sting after they die.

Portuguese Man of War JellyFish. NOAA photo National Ocean and Atmospheric Administration Submitted

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 (above), which is blue or purple in color and looks like a blown-up plastic bag.

The sea nettle jellyfish are responsible for the most stings on Hilton Head. Shore Beach Service lifeguards on the island have seen up to 600 jellyfish stings a day, mostly from sea nettles.

Don’t touch a dead jellyfish if you don’t know what kind it is.

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.

Cannonball jellyfish are also a favorite food of the endangered leatherback sea turtles.

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Mandy Matney is an award-winning journalist and self-proclaimed shark enthusiast from Kansas. She worked for newspapers in Missouri and Illinois before she realized Midwestern winters are horrible, then moved to Hilton Head in 2016. She is the breaking news editor at the Island Packet.