When you think of horseshoe crabs, you don’t usually think of medical breakthroughs. For many of us, horseshoe crabs are just those scary looking things on the beach that we try and stay away from. However, over the last several years, medical scientists have been purposely harvesting horseshoe crabs for their blood, and for a good reason, too.
The first thing you notice about horseshoe crab blood is that it’s a pale shade of blue. This color comes from the copper-based hemocyanin that the crabs use to transport oxygen through their blood. In contrast, mammals use iron-based hemoglobin for the same purpose.
What makes horseshoe crab blood so valuable is its unique anti-bacterial qualities. Horseshoe crabs have been around for 450 million years. In that time, they managed to nearly perfect the art of disease fighting. When a horseshoe crab becomes infected with bacteria, the amebocytes in their blood (sort of like our white blood cells) surround and eradicate the infection at record speed.
For example, white blood cells in mammals can take up to two days to fight a bacterial infection. In horseshoe crabs, thanks to their amebocytes, it can take just 45 minutes. This makes horseshoe crab blood very desirable for medical equipment testing and vaccine research in humans. However, the only way to get horseshoe crab blood is to capture the crabs and bleed them dry in the lab.
With a going rate of $15k for a liter of horseshoe crab blood, the local crab population in many areas has been devastated. To combat that, researchers are now only taking one-third of the crabs’ blood, then releasing them back into the wild. While this has slowed the rate of decline, roughly 10 to 30 percent of crabs used don’t survive.
Never in a million years would I have guessed that horseshoe crabs could actually be used for medical research. It does seem pretty morbid to be catching all those crabs and then draining their blood, but for $15k a liter, I suppose it makes some sense.