SEA GIRT, N.J. (CBSNewYork) — Some surprise visitors showing up on the Jersey Shore are giving beachgoers a scare.

The “cownose” rays are swimming way too close for comfort during these hot summer days. So what are they, and what are they doing here?

Swimmers in Sea Girt and elsewhere along the shore are reporting seeing large schools of the rays in the surf and in the sand. The creatures known for their characteristic square snouts can grow up to four-feet wide from tip to tip, and can come right up to the shore line.

The rays are known to be skittish around people and have a barb on their tail for defense, but experts say they’re essentially harmless.

“These guys are going to make a yearly migration from our southern states up to New Jersey in the warmer months,” said Jennifer Lengares-Meyer from Jenkinson’s Aquarium in Point Pleasant. “We think they’re doing this to follow food sources.”

Lengares-Meyer says this year, there are more sightings because more of the rays are coming closer to the shore. Lifeguards say swimmers have shown concern, mistaking their wings breaching the water’s surface for shark fins.