Its blood is blue and comes from a creature more ancient and resilient than dinosaurs – and even medicine itself has claimed this animal to be “a new life-saving tool”. Not only serving great purposes towards its natural habitat, but now saving countless human lives is the remarkable and bizarre horseshoe crab.
Fuelling the journeys of shorebirds along the Eastern Seaboard and feeding endangered species of turtles and sharks, the horseshoe crabs niche is embedded deeply into the food web of life. This primitive creature has not only evolved to play key roles in nature, but now fulfils a place in the vast growing industry of human medical research. Extracts of the horseshoe crabs blood has been ensuring that pharmaceutical and medical products are free from bacterial contamination – and nothing has worked so dependably like the horseshoe crab.
Why should we worry about bacterial contamination of our pharmaceutical products?
Bacteria are one of the worlds most diverse and abundant living organisms across earth, they really do get everywhere! From the soil to rivers, laying dormant in wood and even lining our mouths and intestinal tract, they will exist in almost every habitat possible. Sounds scary huh? But this isn’t exactly the case. Often enough bacteria are helpful little buddies, stripping waste from the world, aiding in digestion and recycling nutrients.
However, sometimes there are some daring types of bacteria that aren’t so nice and prefer to cause disease. The most popular known are often found in food sources such as Salmonella, and spread by animals such as Tetanus. These that cause damage and disease are known as pathogens and usually require a host for transmission, thriving in the environment for large periods of time. Other members of bacteria considered non-pathogenic can cause disease just by entering parts of our body that are usually bacteria free.
This is why it is important that pharmaceutical products are tested and are sterile-free of living microorganisms before being administrated into the body. The last thing we all need is bacteria finding its way into our bloodstream.
Why the Blood of a Horseshoe Crab?
Sea water is a nicely pre-packed bowl of bacteria soup, containing over one billion Gram-negative bacteria per millilitre of seawater. So as it figures, the horseshoe crab is constantly threatened with the chance of infection. Unlike most mammals (both land and aquatic) the horseshoe crab lacks an immune system and cannot generate antibodies that fight off infection.
Nevertheless the crab is not left defenceless, but contains a number of compounds that will bind to bacteria, viruses and fungi causing all of them to deactivate. These compounds are known as LAL and not only do they bind and deactivate bacterial endotoxins, but the clot formed as a result of the activation of endotoxin provides wound control. The clot both prevents bleeding and forms a physical barrier against additional bacteria.
Today the LAL has become the worldwide standard screening test for bacterial contamination. Every drug and surgical implant certified by the FDA must be tested using LAL.
Are the Horseshoe Crabs Harmed?
Across shallow waters, horseshoe crabs are collected by hand from a small boat using a clam rake, causing no injuries in the process. When coming to deeper waters a dredge is used and unfortunately some crabs do become injured. These are released immediately and most do survive. In total about 500,000 horseshoe crabs are collected annually along the U.S East Coast under interstate regulations.
Once caught, the crabs are transported to the laboratory. This is where the blood is drawn from the crab’s primitive equivalent of a heart. About 20% of the crab’s blood is drawn before being returned the water, where blood volume levels regenerate taking around a week. For the crabs blood cell counts to return to average levels, this takes up to three months.
Should we offer protection?
LAL manufactures have measured mortality rates of less than 3%, yet two recent studies show this is much higher between 10% and 15% of crabs do not survive the bleeding procedure. It may not sound a lot percentage wise, but this accounts for the death of 20,000 to 37,500 horseshoe crabs in one year alone.
The horseshoe crab is becoming heavily harvested, not only has it supported the fishing industry for over 100 years but has also been heavily imposed on for medical research – and the two linked together are causing consequences. Populations of the horseshoe crab are declining. Now whether you see it important to protect these creatures for selfish reasons of pathogen protection, we must also push ourselves to seeing the bigger picture.
We must marvel at these ancient creatures we have present in today’s climate and the essential purposes they perform. If it wasn’t for horseshoe crabs our favourite shorebirds would not be as abundant, filling beaches and cliff sights with diverse calls and feathers. endangered species of turtle may have already become extinct. The excitement of seeing one of these bizarre and primitive creatures scuttling across sands would be lost. It’s not everyday we get to see some of the first species that inhabited earth.
If these could survive what the dinosaurs didn’t, is it fair to wipe them out because we are not as evolved immune-wise, so depend on there help? Is it fair to force them to depart with their blue blood which has taken millions of years to evolve, simply because we are too impatient to see what we will evolve into ourselves? Is it okay to keep skipping our own stages and replacing it by taking from others? We only have time to find out. But in the meantime we need to keep nature in contact, as the most important rule in evolution is to evolve together. Without nature, we will strip our competition, instincts, natural products, fertilisers and food that ensures our survival.