The horseshoe crab was weird long before it had a name, a survivor whose 10 eyes have seen dinosaurs, mass extinctions and mankind’s march up the food chain.

For humans, these living fossils have proved profitable. First, it was discovered that horseshoe crabs made good bait for catching conch and eel, and later a lucrative use was found for their lifesaving blood.

Now the South Jersey shores of the Delaware Bay have become a battleground for a fight over the ancient creature, involving fishermen, environmentalists, politicians, scientists and bird lovers.

Last month, New Jersey state Sen. Jeff Van Drew, a Democrat who represents parts of Cape May and Cumberland counties, introduced legislation that would lift a ban on harvesting horseshoe crabs that’s been in place since 2008.

Van Drew’s bill would face strong opposition from environmental groups. It is in committee in both houses of the Legislature, and no vote has been scheduled.

“The moratorium might be sexy and cool,” Van Drew said recently, “but it just doesn’t make sense. ”

The ban’s sexiness, Van Drew said, is attributable not to its protection of the horseshoe crab, but to its protection of an impressive and imperiled little bird called the Atlantic red knot, recently added to the endangered-wildlife list, at the expense of a few dozen local fishermen who had been harvesting horseshoe crabs for years.

“A lot of these people who supported the ban never even saw a horseshoe crab in their life,” he said. “It was just so cool to say, ‘Oh, boy, we’re saving the environment. ‘ ”

A survivor through time

The subject of all this attention is not really a crab at all, but an underwater arthropod that resembles a scorpion with milky blue blood and a drab, helmetlike shell. It scuttled along the sea floor in its coat of armor for hundreds of millions of years, eating and breeding, untouched by predators and evolution as Earth’s slate was wiped clean.

“It’s a creature that’s outlived 99 percent of every species on Earth, and I think it will be here long after humans have passed on,” said Anthony D. Fredericks, author of Horseshoe Crab: Biography of a Survivor.

“I would say it’s the most fascinating animal in the world, though I’m a little biased. ”

And without horseshoe crabs, environmentalists say, there would be no Atlantic red knots.

Each spring, the red knots fly 9,300 miles from their winter home in Argentina’s Tierra del Fuego to their breeding ground in the Arctic and, like most tourists passing through Jersey, they find a major rest stop here to refuel. Scientists estimate that 90 percent of the world’s Atlantic red knots stop in the Delaware Bay, exhausted from their journey and ready to fill up on the fatty horseshoe-crab eggs before they shove off for the Arctic.

“These birds have to triple their weight here, and there has to be a certain amount of eggs on the beach,” said Jeff Tittel, director of the New Jersey Sierra Club. “We shouldn’t jeopardize a whole ecosystem for bait. ”

The relationship between the migratory bird and its famous prey is depicted in “Sex and Gluttony,”a bay diorama at the Wetlands Institute in this Cape May County township. The annual migration brings in millions of dollars, Tittel said, as bird-watchers and environmental groups converge upon the county to watch it.

“This ecological link is globally recognized and, unfortunately, humans have played a dramatic role in the reduction of both populations,” said Dan McLaughlin, a research coordinator at the institute. “People come from all over the world to see it. ”

Lawrence Niles, a wildlife biologist with the Conserve Wildlife Foundation, conducted research that helped prompt the moratorium in hopes that red-knot numbers would rise as the horseshoe-crab population increased. He believes that Superstorm Sandy could have damaged horseshoe-crab breeding grounds last year, as well, and thinks the ban must stay in effect.

“There’s just too much riding on this,” Niles said.

The ban affects about 36 licensed fishermen who formerly harvested horseshoe crabs by hand and used them as bait for conch and eel, or sold them to biomedical labs that drained their blood for its ability to detect bacterial contaminants in intravenous drugs and vaccines. The Atlantic States Marine Fisheries Commission, formed in 1942 to manage fisheries in 15 states, still allows New Jersey an annual harvest quota of 160,000, but the state forbids the harvesting, and heavy fines are levied on anyone in possession of a horseshoe crab.

Van Drew said that his bill would permit New Jersey fishermen to fill the commission’s quota without marking a return to the 1990s, when millions of crabs were harvested yearly. Both Van Drew and license-holders fear that the commission will allow more crabs to be harvested in Delaware, Maryland and Virginia if New Jersey doesn’t use its quota.

‘It’s liquid gold’

“We’re trying to save the world all by ourselves here in New Jersey, and we’re messing it up,” said Walter Chew, a retired fisherman, as he gazed out upon Bidwell’s Creek, in Cape May County, last week.

In the 1960s, scientists discovered that an enzyme in the horseshoe crab’s blood could help detect potentially fatal bacteria in vaccines. Today, horseshoe-crab blood is used throughout the world for this reason, and there’s a good chance that it kept you safe when you’ve had an injection.

“It’s liquid gold,” Chew said.

Limuli Labs, in Cape May County, has New Jersey’s only scientific permit to harvest horseshoe crabs for their blood. The Daily News was unable to contact anyone at Limuli labs for comment, and other laboratories that bleed horseshoe crabs in the United States declined to comment. The industry often claims that as little as 10 percent of the harvested crabs die from the bleeding, but Niles said that little is known about the medical harvest, and he believes that the mortality rate is higher.

“The bleeders are killing more crabs than they say, more than 10 to 15 percent, and nobody knows what they’re doing, because they don’t have to share their data with scientists,” Niles said.

“They’re making huge amounts of money. ”

Both Van Drew and Niles said that they’ve been mischaracterized by those who disagree with them. Environmental groups have questioned Van Drew’s motivations, and fishermen have questioned Niles’ science.

“There’s this pretense that I don’t care and the environmentalists don’t care about fishermen, but the seafood industry in Cape May is making money hand over fist,” said Niles. “The corporations, not the people. ”

For his part, Van Drew said he’s got nothing to gain politically by advocating for three dozen fishermen who want to harvest horseshoe crabs again.

“I obviously want to save the birds and obviously treasure the horseshoe crabs,” he said. “I’m not some madman that wants a species to go extinct. “