Horseshoe crabs are older than the dinosaurs. They've been around for 450 million years, which means they watched the rise and fall of millions of other species, and survived ice ages.
As well as being incredible 'living fossils', they have also helped to keep most of us alive. If you have ever had a vaccine, chances are that it was tested for safety using horseshoe crab blood. And they're about to save even more lives, because they're playing their part in the creation of a Covid-19 injection.
What is horseshoe crab blood used for?
Horseshoe crab blood is bright blue. It contains important immune cells that are exceptionally sensitive to toxic bacteria. When those cells meet invading bacteria, they clot around it and protect the rest of the horseshoe crab's body from toxins.
Scientists used these clever blood cells to develop a test called Limulus Amebocyte Lysate, or LAL, which checks new vaccines for contamination. This technique has been used all over the world since the 1970s to stop medical professionals giving out jabs full of bad bacteria that could make humans very sick.
It's great for humans, because vaccines save us from all sorts of unwanted diseases, including measles and mumps. It's not so great for the horseshoe crabs: thousands of them are rounded up and bled every year.
Horseshoe crabs and Covid:-
The world is rushing to find a safe vaccine to fight Covid-19, the viral lung disease which has swept the planet.
More than 100 different vaccines are being tested in the hope that one will work. The successful jabs will have to be carefully checked before they are rolled out.
In many parts of the world, researchers will be relying on horseshoe crab blood in those important tests. And since we'll want to vaccinate millions of people in a short space of time, horseshoe crabs could play a big part.
Threat To Horseshoe Crab Population
According to Buglife, hundreds of thousands of the marine arthropods are caught and transferred to laboratories to drain their blood from a vein near their heart. While the US releases the crabs with around 15% (50,000) of them dying, in China, 100% of the bled crabs die as they are sold for food and chitin – a derivative of glucose – production.
Other pressures that endanger the crabs include bait catching, habitat loss as seawalls stand where they lay their eggs, and pollution.
“The main threat is the use of the crabs for bait, in the US the species could be added to the Endangered Species Act and taking and killing for bait out lawed,” Shardlow said. “In China the species could also be protected from use in bait and animals that have been bled could be required to be returned to the sea alive.”
Thank you.