‘We’re Wiping Out One of the World’s Oldest and Toughest Creatures’: Green Groups Urge Endangered Protections for Horseshoe Crabs

Horseshoe crabs have been on Earth for more than 450 million years — since before the dinosaurs. They are more closely related to spiders and scorpions than crustaceans and can live as long as 25 years.

Despite having lived through ice ages, the breaking apart of the continents and many other geological and atmospheric changes to our planet, the survival of these resilient creatures has been put in jeopardy by recent human activities.

On Monday, a petition was filed by the Center for Biological Diversity, American Bird Conservancy, the Humane Society of the United States and 20 other environmental organizations requesting that the National Oceanographic and Atmospheric Administration (NOAA) and the U.S. Secretary of Commerce —through NOAA Fisheries — list the American horseshoe crab as threatened or endangered. Populations of the ancient arthropod have been decimated in recent decades due to habitat loss and overharvesting.

The petition also asks that critical habitat be designated for the species.

“We’re wiping out one of the world’s oldest and toughest creatures,” said Will Harlan, a Center for Biological Diversity senior scientist, in a press release from the Center for Biological Diversity. “These living fossils urgently need Endangered Species Act protection. Horseshoe crabs have saved countless human lives, and now we should return the favor.”

Harmless to humans, horseshoe crabs are equipped with full body armor and have 10 eyes. They lay their eggs along the Gulf and Atlantic coasts in spawning events each spring.

The largest population of horseshoe crabs can be found in the Delaware Bay, where the species has declined by two-thirds over the past 30 years.

Commercial eel and whelk fisheries harvest horseshoe crabs for use as bait, and though their populations have been driven to historic lows, harvest quotas have still been increased by regulators.

Horseshoe crabs are also harvested by biomedical companies that drain them of their blue blood for use in detecting drug toxins and in medical devices. Since 2017, the harvesting of horseshoe crabs for their blood has nearly doubled; in 2022, almost one million were harvested for this purpose. Europe uses synthetic alternatives, but U.S. companies have dragged behind in adopting them.

“The continued reliance on horseshoe crab blood by pharmaceutical manufacturers has led to a rapid decrease in the population of this important species,” said Kathleen Conlee, the Humane Society’s vice president of animal research issues, in the press release. “Fortunately, there are non-animal alternatives that can replace the use of horseshoe crab blood and help protect these amazing animals from further overharvest.”

Another big driver of species decline for horseshoe crabs is habitat loss. Development, sea level rise and shoreline hardening are destroying spawning beaches throughout their range.

As population numbers of these incredible animals have fallen, so have those of species like endangered sea turtles, birds and fish. One particular shorebird species — the rufa red knot, a type of sandpiper — feeds on the eggs of horseshoe crabs along its 19,000-mile migration route from the Arctic to South America. In 2015, the red knot was listed under the Endangered Species Act as threatened. A contributing factor to the decline of the red knot cited in the listing decision was the harvesting of horseshoe crabs.

“Horseshoe crab eggs are incredibly nutrient dense, sustaining the federally threatened red knot on their long migratory journey,” said American Bird Conservancy Vice President Steve Holmer. “Greater protection of the horseshoe crab is needed to fully recover the red knot, as well as conserve other shorebird species, such as the ruddy turnstone and semipalmated sandpiper.”

Asia’s tri-spine horseshoe crab — an American horseshoe crab sister species — is almost extinct due to similar threats.

“It is clear from the available science that the current fisheries management policies are failing to protect and sustain these ancient mariners,” said Tim Dillingham, American Littoral Society’s executive director, in the press release. “We must do more to keep them and the red knots and other life that depend on them from disappearing from this Earth.”