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Visitors to mid-Atlantic beaches this time of year may see odd creatures on the shore. They look like they belong in the dinosaur age, and they're horseshoe crabs. Scientists worry their numbers are declining, and as NPR's Jeff Brady reports, that's why volunteers fan out along the coast to count horseshoe crabs each year.
JEFF BRADY, BYLINE: On a beach and near Dover, Del., horseshoe crabs are lined up for miles. They've come ashore for their annual spawning season. The females are larger, as big as a dinner plate. The shell has a horseshoe shape. From a few steps back, they look like green army helmets.
FAITH HEWES: And you could tell when they're old.
BRADY: How can you tell when they're old?
FAITH: Because they have a lot of stuff on their backs and a lot of barnacles.
BRADY: Faith Hewes learned about horseshoe crabs from her dad. Jim Hewes is a seventh grade science teacher. He volunteers to lead counting teams. Just before 9 p.m., it's nearly dark. High tide is receding, and he gives instructions to a half-dozen volunteers. They hold big white squares made of plastic pipe.
JIM HEWES: When you put in your square, go right to the water's edge, OK? Drop it in. And again, remember, you're counting the crabs that are only within the square itself.
BRADY: Two teams do this 50 times each along a mile of this Delaware beach. Hewes says if a crab walks out of the square, count that one too.
HEWES: Alright, guys, let's have fun, and let's count some crabs.
BRADY: With rubber boots and headlamps, the volunteers dig through the many males to find the few females laying eggs in the sand.
TOM HUBER: You count the males. I'll check for females.
MELANIE HUBER: OK.
BRADY: Tom Huber and daughter Melanie bend down and dig in. Son Benson stands with a clipboard.
BENSON HUBER: They count them. I just write it down and anything - like if they have tags, I have to record those as well.
BRADY: Some crabs are tagged so researchers can track where they go.
HUBER: OK, so 13 males, 2 females.
BRADY: There are plenty of crabs tonight, but overall, there's still concern. The fishing industry uses horseshoe crabs for bait. Migratory birds eat their eggs, and biomedical companies use its blue blood to make a special clotting agent. Kirby Rootes-Murdy with the Atlantic States Marine Fisheries Commission says here in the Delaware Bay region, numbers are stable, and south of here, the population is increasing.
KIRBY ROOTES-MURDY: What we are seeing in terms of concerning evidence is a decrease in abundance for the New York and kind of New England regions.
BRADY: And Rootes-Murdy points out another important thing about horseshoe crabs. Turns out, they aren't really crabs.
ROOTES-MURDY: It's pretty nuts that they have the name horseshoe crab, but they're much more closely related to spiders and scorpions than they are to actual blue crabs that people are familiar with.
BRADY: Back at the shore, Maggie Pletta with the Delaware National Estuarine and Research Reserve says don't let that spider scorpion thing worry you.
MAGGIE PLETTA: They can't sting you. They're not venomous. They're not using their tale as a spear. You know, so if you see them on the beach and they're stuck upside down, flip them over. Return them the favor. Just flip them, and let them get back to doing their business.
BRADY: Volunteers will be out here on the beach at night through June 18 this year counting horseshoe crabs. At Kitts Hummock Beach near Dover, Del., Jeff Brady, NPR News.