The horseshoe crab is a paradoxical creature: Its spiky tail and helmet-shaped body make it one of the most medieval-looking animals, while its milky blue blood is essential to ensure the safety of cutting-edge biomedical devices and drugs.
For decades, biotechnology companies have harvested horseshoe crabs and bled them to extract a substance used to create a sensitive test for toxic components of bacteria in intravenous drugs and devices.
Studies have found that the vast majority of horseshoe crabs survive the procedure, but researchers at Plymouth State University and the University of New Hampshire began to wonder whether the bleeding might have other, less severe effects that could play a role in a recent population decline.
In a study recently published in the journal Biological Bulletin, researchers collected 56 female horseshoe crabs from Adams Point in Durham, N.H.
For half the crabs, researchers emulated the biomedical harvest, including the time they would typically spend out of the water in the sun or on a truck. Around 30 percent of their milky blue blood was removed, as is done in the biomedical industry, and then they were returned to tanks.
Nearly a fifth of the horseshoe crabs died after bleeding, which was expected. But they also found that the animals seemed to become very lethargic. The internal clock that they used to synchronize their behavior with the tides seemed to go out of whack. The bloodletting also seemed to decrease the quality of the blood, which could have had possible effects on their ability to fight off infections. The changes lasted more than a week.
“We reasoned if you take a fair amount of blood out of animals and transport them for two to three days and it occurs during the peak of the breeding season, these animals may be out of commission, behaviorally, for a while,” said Christopher Chabot, a professor of neurobiology, physiology, and behavior at Plymouth State. “Breeding season is only four weeks long — if they’re captured and brought back, perhaps they don’t breed.”
That is the next question for Chabot. He hopes to be able to detect what effect the biomedical harvesting has on reproduction.Carolyn Y. Johnson can be reached at email@example.com. Follow her on Twitter @carolynyjohnson.
Clarification: A story that ran in Science in Mind incorrectly described how a substance in horseshoe crab blood is used by the drug and medical device industries. The test detects toxic components of bacteria.