Groton - Crouched in the sand on the bay side of Bushy Point Beach under dark, drizzly skies, Mary Ellen Mateleska gave a quick, hands-on lesson to Ken Beatrice on how to handle the wet, upside-down creature in front of him, flailing its legs and tail in a determined attempt to right itself.
"You have about 30 seconds to get his measurements before he flips," she said, demonstrating how to grasp the horseshoe crab, sometimes called a "living fossil" because of its 350 million years surviving on this planet, persisting through five mass extinctions relatively unchanged.
Quickly, Beatrice, who had come with his wife Bonnie from their home in East Haddam to spend this cold, rainy May night with one of nature's most unique creatures, snatched up a nearby ruler and began sizing up this specimen of limulus polyphemus.
"He's a male, 24 centimeters," Beatrice said. "He's a two."
The last number refers to a 1-to-3 rating system for the animal's overall condition, with a one given to the healthiest of these ancient arthropods, which are closely related to spiders and scorpions.
After the measuring and rating came the tagging. Mateleska, curator of conservation education at Mystic Aquarium, showed Beatrice how to use a special awl to bore a small hole into the crab's dun-colored shell and attach a numbered white tag.
"It might take a little bit of elbow the first time, but then it gets easier," said Mateleska, a veteran of five horseshoe crab-tagging seasons.
Beatrice and Mateleska were among nine volunteers who gathered at Bluff Point State Park Thursday evening, carrying raincoats, waders and rubber boots from the parking lot to Bushy Point Beach, about a mile down the park's main trail. The group was recruited as part of Project Limulus, a multi-state, multi-year effort to collect data on this important but still mysterious species.
The U.S. Fish & Wildlife Service heads the overall project, while Jennifer Mattei, biology professor at Sacred Heart University in Fairfield, directs the Connecticut component. It is also supported by Connecticut Sea Grant, based at the University of Connecticut's Avery Point campus in Groton.
Since starting about 15 years ago, Project Limulus has relied on citizen-scientists like the group at Bluff Point. Earlier this month, Mattei taught a training class at the aquarium for about 25 prospective volunteers who would be heading to local beaches, including Sandy Point and Lord's Point in Stonington as well as Bluff Point, to count, measure and tag the crabs.
The groups do their work on evenings when the full moon or new moon coincide with an early evening high tide. That's when the crabs come into shallow waters to mate and lay eggs in the sand. A single female lays up to 100,000 eggs each spring, many of which become an important food source for shore birds.
"Horseshoe crabs have survived through the big five extinctions, but can they survive us?" Mattei asked near the beginning of her talk.
The crabs, she explained, have endured because they are generalists, highly adaptable to different conditions of water temperature, oxygen level, salinity, food source and even pollution level. But while they are not considered an endangered or threatened species, their numbers have been declining and there is concern about their continued survival.
"The armoring of our shores (with seawalls and other development) destroys breeding areas for the horseshoe crabs," she said.
Mattei showed one photo of crabs piled high on a turn-of-the-century dock. She explained that the creatures once were harvested by the thousands and turned into fertilizer. Today, they are harvested as bait for whelk and eel fishing, with an estimated 40,000 to 60,000 crabs being taken annually from the Connecticut side of the Sound, she said.
Concern about the crabs extends beyond the environmental community into medicine. Blood extracted from horseshoe crabs that are captured then released is used to test the sterility of vaccines, medical devices and pharmaceuticals, and no synthetic substitute has been found. In addition, research into the eyes of horseshoe crabs - each crab has 10 - has contributed much to current understanding of how the human eye works.
"But there's still so much we don't know," said Rick Newton, who has coordinated the local Limulus volunteers for the past five years through the Denison Pequotsepos Nature Center. "How do they know when the full moon cycle and new moon cycle is?"
While the other volunteers sloshed into the water to bring crabs ashore, often cradling entwined pairs interrupted in their procreative pursuits, Newton held a clipboard and pencil, recording the measurements, ratings and tag numbers. Information from any crabs found with tags attached in previous years also was recorded.
The data he's helping to collect, he said, will feed into the larger research project that ultimately will give scientists a better understanding of the overall size, health and habits of the North American horseshoe crab population, which extends from Maine to Mexico.
"We've done about 200 tags so far this spring," Newton said. "We'll do the count through July, for four more moon cycles, depending on when we run out of tags."
In this region, he said, Sandy Point is the "hot spot" for horseshoe crabs, drawing many more in a single night than his small bands of volunteers can tag.
"One night, we tagged 300 there, but there were probably 400 or 450," he recalled.
On Thursday, the group tagged 43 crabs - 22 females and 21 males, mostly in pairs except for one female with two males attached. It also found and recorded data on eight previously tagged crabs.
Susan Andrle of Ledyard was among the volunteers, coming with her husband Bob as a way to fill the new commitment she's made to donate time to conservation projects since finishing the state Department of Energy and Environmental Protection's Master Wildlife Conservation Program.
"I used to work at Pfizer, and then I got laid off, so now," she said, wading into the water to scoop up a pair she'd just spotted, "I just do whatever's fun."
Sloshing through the water nearby was Vicky Rivera, a guest services specialist at the aquarium, wearing chest-high waders and a headlamp as she scanned the waters.
"Oh, I've got a pretty couple," she said, setting the pair on the sand. "For me, the exciting part is finding them."