SOUTH PORTLAND – The discovery of a crab in South Portland appears to be the first evidence that a potentially harmful species from Asia has reached Maine’s shores.

A boy attending a day camp found on Wednesday what appears to be an Asian shore crab, also called a Japanese shore crab. It was identified Friday by a marine educator who saved it and by an aquaculture technician at Southern Maine Technical College.

Asian shore crabs have overtaken tide pools along the Atlantic coast, but until last week had been found only as far north as New Hampshire.

It’s feared that the crab’s aggressive nature and large appetite could harm other intertidal residents such as clams and baby lobsters.

The crab matches descriptions posted on Internet alerts about the invader. The brownish-green crab is about the size of a half dollar, with three spines on each side of its shell and bands on its legs.

Ten-year-old Casey Gillespie found the crab while exploring a small cobble and rock beach next to a dock at the college.

The beach is home to Fish Camp, a summer day camp run by marine educators Jeff and Deb Sandler. The campers had been on the lookout for an Asian shore crab.

Deb Sandler – known to campers as Mrs. Fish – had explained that the species appeared in New Jersey in 1988, apparently arriving from Asia in the hull of a ship. She explained that the last foreign crab to arrive in Maine, the green crab, took over tide pools and started eating up soft-shell clams.

“The kids were out exploring and this one little guy, Casey Gillespie, came running up to me and said, ‘Mrs. Fish, Mrs. Fish! I found the Asian crab!”‘ she said.

Casey is from Connecticut, where large numbers of Asian shore crabs have taken over tide pools.

“It would be very nice if it was never found,” said Tom Long, the technician in the marine biology department who helped identify Casey’s discovery as an Asian shore crab.

Sandler said the campers wanted to kill it to protect Maine’s tide pools, but cooler heads prevailed. The crab is safe in the camp’s tank and will serve as the subject of a lesson for campers next week.

“I’ll definitely hold onto it,” Sandler said.