Horseshoe crabs, vital “living fossils” for vaccine safety

The group walks to shore laying a measuring frame on the sand to count the horseshoe crabs, straightening those tipped over by the tide.

With their helmet-like shells, spike-like tails, and five pairs of legs connected at the mouth, these horseshoe crabs aren’t immediately endearing.

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

Besides being harmless to humans, they are really easy to like, once you understand themexplains to AFP Laurel Sullivan, who works for the State of Delaware to inform the public about these invertebrates.

For 450 million years, these creatures from another age have roamed the oceans of the planet, seeing the dinosaurs appear and then die out and the first fish transform into land animals and then into humans.

Today, however, these living fossils are listed as a vulnerable species in America and endangered in Asia, due to habitat reduction, overexploitation for food or bait, and use by the pharmaceutical industry, a major growth sector , especially since the COVID-19 pandemic.

The term crab is not entirely appropriate to designate these animals, which are more like spiders and scorpions, and are composed of four subspecies: one lives on the Atlantic coast of North America and in the Gulf 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 bringing it to their mouth.

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

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

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

Nivette Perez-Perez, a scientist with the Delaware Inland Bays Center, points to a large egg strip that stretches across most of the beach at the James Farm Ecological Reserve, upon which black-headed gulls with bright orange beaks swoop down. rush to feast.

Like others in the region, Ms. Perez-Perez succumbed to the charm of horseshoe crabs. you are so cuteshe says to a female she picks up to show her anatomical features.

Mating is a dangerous activity for horseshoe crabs, because it is on the beach that they are most vulnerable: with the tide, some end up on their backs, and although their long hard tails help them to stand up, not everyone is so lucky. About 10% of the population dies each year, their bellies baked by the sun.

In 1998, Glenn Gauvry, founder of the Group on Ecological Research and Development, participated in a campaign called Just turn them overencouraging the public to help the crabs that are still alive.

What matters most is winning heartshe told AFP on the beach in Pickering, Delaware Bay, a cap bearing his slogan and adorned with badges of horseshoe crabs on his head.

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

Each year, approximately 500,000 horseshoe crabs are harvested 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 like hip replacements.

This process kills about 15% of horseshoe crabs, with survivors released back 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 those two things are mutually exclusivesays Allen Burgenson, of the Swiss biotech company Lonza, which manufactures the new test.