What were those dang sea lice? Ocean City now says it was crab larvae — but marine expert disagrees

Jellyfish larvae, also called sea lice, and sand fleas might be found at the beach. Which showed up in Ocean City this summer, though, is unclear.
Jellyfish larvae, also called sea lice, and sand fleas might be found at the beach. Which showed up in Ocean City this summer, though, is unclear.

Since we reported on an outbreak of sea lice in Ocean City last week, The Baltimore Sun has received emails from readers that the critters seen this summer were actually baby crabs — not jellyfish or anemone larvae.

That’s the explanation Captain Butch Arbin of the Ocean City Beach Patrol stands by. Arbin said that although the critters don’t look like anything you’d get on your table at Phillips, they’re still crabs. “There’s all kinds of different crabs. There’s little crabs you see on the beach. These could be the larval forms of those.”


Some readers, too, suggested they were crabs. “I believe the larvae are crab larvae also known as crab megalops,” wrote reader Geoff Gursky, who attached a picture of larvae that came out of his swimsuit.

“You will clearly see eyes, legs and if you look closely enough, pinchers. We also found half a dead crab today in OC that had a few of these larvae in the shell.”

But one marine expert The Sun spoke to said that’s not likely.

Ian Bricknell teaches marine science at the University of Maine, and recently gave a talk on sea lice here in Maryland.

“I’m happy to talk about parasites and the yucky side of marine life with anybody,” Bricknell said.

Bricknell chiefly studies sea lice that affect fish — like those that recently cost the salmon industry around $1 billion in losses. But those sea lice are different from those that caused problems in Ocean City.

Sea lice that affect humans are not lice at all, but can include comb jellies — which have caused sea lice outbreaks in Florida. Others can be sand flea larvae, amphipods, which Bricknell believes might be responsible for the outbreak in Ocean City.

They become stuck in people’s swimsuits, then sting or pinch while trying to get out.

Crab larvae lack the ability to bite or sting, and thus wouldn’t be an irritant, Bricknell said. “I’m not aware of crab larvae ever being associated with sea lice.”

But sand flea larvae, or amphipods, look a little bit like crabs — and cause the type of irritation swimmers reported in Ocean City.

In one highly publicized case last year, an Australian teenager’s legs began bleeding profusely after he’d been bitten by a type of sea lice Down Under. Experts said amphipods were likely the culprit.

Arbin, who also teaches at the James E. Richmond Science Center, disagrees with that assessment, telling The Sun in an email, “I still believe they are crab.”

Whether the recent sea lice outbreak were caused by crab larvae, sand flea larvae, or something else, one thing is for sure: They itch.

To prevent confusion, some use the term “sea bather’s eruption” to refer to the rash that people sometimes get from types of ocean larvae.


Arbin, who has worked with the beach patrol for 46 years, knows this from personal experience. He got sea lice eruption himself once, back in the 1970s. After coming home from a day at the beach, he changed clothes and left for his job at a boardwalk pizzeria, and felt the itch.

“Unfortunately they get into places where it’s kind of embarrassing to itch,” he said.

Though swimmers might attempt to avoid problems by wearing T-shirts and rash guards, “that’s the exact opposite of what you want to do,” Arbin said. Extra clothing actually creates more of a problem as it offers crabs a place to become stuck.

However uncomfortable, Arbin said, the condition rarely if ever poses a serious medical problem. It’s an itchy nuisance. Swimmers can rinse off with fresh water.

There’s good news for Labor Day beachgoers: The outbreak in Maryland lasted only about a week, Arbin says.

“Right now it’s pretty much gone,” Arbin said.