Horseshoe crabs, “living fossils” vital to vaccine safety


On a moonlit night, scientists and volunteers wander a protected beach in Delaware Bay to observe horseshoe crabs, or “horseshoe crabs,” which spawn by the millions along the east coast of the United States. late spring and early summer.

The group heads towards the shore, placing a meter on the sand to count the horseshoe crabs, straightening those overturned by the tide.

With their helmet-shaped shells, pointed tails, and five pairs of legs attached to their mouths, these horseshoe crabs aren’t immediately eye-catching.

But these strange marine animals are vital to vaccine safety: their bright blue blood, which coagulates in the presence of harmful bacterial compounds called endotoxins, has been essential for testing the safety of biomedical products since the 1970s, when they were introduced. rabbit tests. abandoned.

In addition to being harmless to humans, “they’re really easy to love once you understand them,” says Laurel Sullivan, who works for the state of Delaware at AFP, telling the public about these invertebrates.

For 450 million years, these creatures from another era have roamed the planet’s oceans, seeing dinosaurs appear and then go extinct and the first fish transform into land animals and then humans.

Today, however, these “living fossils” are listed as vulnerable species in America and endangered in Asia, due to reduced habitat, over-exploitation for food or bait and their use by the pharmaceutical industry. , a rapidly growing sector, especially since the covid19 pandemic.

– Vital role-

The term “crab” is not entirely appropriate for these animals, which are more like spiders and scorpions, and are made up of four subspecies: one lives on the Atlantic coast of North South America and in the Gulf of Mexico, and the other three in Southeast Asia.

Horseshoe crabs, also called Moluccan crabs, have 10 eyes and feed by crushing their food, worms and clams, between their legs, before taking it to their mouth.

Males are significantly smaller than females, which during breeding gather in groups of up to 15 individuals.

To reproduce, males spray their sperm on clusters of 5,000 golf ball-sized eggs, which they lay on the sand.

These eggs, tiny green balls, are also a vital food source for migratory birds, including the Near Threatened Red Knot.

Nivette Perez-Perez, a scientist at the Delaware Inland Bays Center, points to a large strip of eggs that stretches across much of the beach at the James Farm Ecological Reserve, swooping over by black-headed gulls with bright orange beaks. .

Like others in the region, Ms. Perez-Perez has succumbed to the allure of horseshoe crabs. “You’re so pretty,” she tells a woman who she picks up to show her anatomical features.

– Return them –

Mating is a dangerous activity for horseshoe crabs, as it is on the beach that they are most vulnerable.

With the tide, some wind up on their backs, and although their long, hard tails help them stand up, not everyone is so lucky. About 10% of the population dies each year, with their bellies roasted by the sun.

In 1998, Glenn Gauvry, founder of the Group on Ecological Research and Development, took part in a campaign called “Just Turn Them Over”, encouraging the public to help live crabs.

“Winning hearts is what matters most,” he told AFP on Pickering Beach in Delaware Bay, a cap bearing his slogan and adorned with horseshoe crab badges on his head.

“If we can’t get people to care for these animals and feel close to them, they’re less likely to want legislation to protect them,” he explains.

Approximately 500,000 horseshoe crabs are harvested annually for the pharmaceutical industry. Their blood serves in a chemical called Limulus Amebocyte Lysate, which identifies a type of bacteria that can contaminate drugs, needles, and devices such as hip replacements.

This process results in the death of approximately 15% of horseshoe crabs, with the survivors being released into the sea.

A new synthetic process, called recombinant factor C, shows promise but has yet to be regulated.

Horseshoe crabs are a “limited source with potentially infinite demand and these two things are mutually exclusive,” says Allen Burgenson of Swiss biotech company Lonza, which carries out the new test.



Leave a Comment