What has twelve legs, ten eyes and one tail? It's not a creature from science fiction — it's the horseshoe crab, a so-called living fossil that some scientists say is now threatened with extinction.
That's at the center of a lawsuit alleging the federal government has so far failed to include them for protection under the Endangered Species Act.
In Maine, citizen scientists are monitoring the Atlantic horseshoe crab along the coast.
The salty ocean waters are warming along the shore in Great Salt Bay, and love is in the air.
"And there is a horseshoe crab — for lack of a better word — orgy that occurs every year at this time, where they're mating," says Sharon Morrill, a volunteer with the Coastal Rivers Conservation Trust in Damariscotta.
Morrill is part of a small group that monitors horseshoe crabs at two sites every day at high tide during their spawning season, from mid-April to mid-June.
Today, she's joined by her sister Lynn Bernier, who's also a volunteer. They're both dressed in waders, and the rounded toe of their boots is not unlike the shape of a horseshoe crab, which looks like an upside-down bowl with a tail.
When Morrill sees my polka dot rain boots, she issues a warning.
"You have very attractive boots on, so don't be surprised if they think you're female, and they're on your boots. This happens too," she says.
The pair make their way through tall grass to the shore, where they first measure water temperature and salinity. Horseshoe crabs — which, by the way, aren't crabs and are closer to spiders, ticks and scorpions — prefer warm, salty water for spawning. Next, Morrill and Bernier wade through knee deep water to begin counting.
"We've got one single, one double, and we're gonna walk this way," Morrill says to Bernier, who records the data.
Morrill is careful not to disturb mating doubles. But she sees a single crab that's dead, picks it up and turns it over.
"Now this is a male," she says. "They have like, boxing gloves."
It's a pair of small, bulbous legs that males use to clasp onto females so they can fertilize the thousands of tiny eggs she'll lay.
"Boxing gloves are so apropos. They are frisky, feisty, these males," Morrill says.
"We're guessing they're teenagers or something," Bernier says with a giggle.
Horseshoe crabs are often called living fossils. They've roamed the Earth since well before the dinosaurs. But some scientists say they're now threatened with extinction.
That's at the center of a recent lawsuit filed by the Center for Biological Diversity, a national organization that alleges the federal government should include the crabs for protection under the Endangered Species Act.
In Maine, Sarah Gladu oversees the horseshoe crab monitoring program for Coastal Rivers Conservation Trust.
"These horseshoe crabs have probably been coming to these sites as they exist for about the past 4,000 years," she says.
Gladu says 20 years of data collected by volunteers have revealed that this population appears to behave differently than horseshoe crabs found farther to the south.
"Their spawning seems to be triggered by temperature more so than by the full moon or the high tide stage and so forth that sometimes is seen in other places in the world," she says.
As to whether the population is decreasing, Gladu says their small, scrappy nonprofit hasn't been able to do a full analysis to know for sure. But Downeast, where the Friends of Taunton Bay have been monitoring horseshoe crabs for nearly three decades, the data show a clear trend.
"The decline was gentle for awhile, and then somewhat precipitous," says the group's Frank Dorsey.
He says they used to find more than 100 a day, but the number dropped by more than half with the arrival of invasive green crabs, which eat horseshoe crabs' eggs and can destroy eelgrass habitat. Dorsey says the numbers have somewhat rebounded, but he supports the lawsuit filed by the Center for Biological Diversity.
"The main thrust of it would be to stop the harvest of horseshoe crabs for their blood," Dorsey says.
Their blood has a unique clotting agent that's used for drug safety testing, despite synthetic alternatives.
Horseshoe crabs aren't harvested in Maine. But the Center argues in its lawsuit that the biomedical harvest in the U.S. has doubled over the past seven years, and the Atlantic horseshoe crab population is facing additional pressure due to development, pollution, erosion, and climate change.
The lawsuit specifically notes that the population in the Gulf of Maine may be in danger of extinction or will be in the foreseeable future.
Back in Damariscotta Mills, Morrill is in the middle of her count when she makes an exciting discovery.
"Oh I hear them over here! Oh, look! look!" she calls out.
A cluster of nearly a dozen horseshoe crabs clamber over each other to try to get to a female.
"Sometimes it's like a conga line," Morrill says. "Sometimes it's like a scrum in rugby."
Male horseshoe crabs do form lines behind a female — sometimes as many as seven, says Gladu. It's unclear why, she says, and that's another reason to keep monitoring them. Because even though they've roamed the Earth for hundreds of millions of years, there's still a lot we don't know about them.
