By Patricia Houser
For Nature’s Sake
Patricia Houser
Anyone who’s had a vaccine in the last 30 years or needed a catheter, insulin shot or surgical implant might offer a nod of thanks, on their next beach walk, to the nearest horseshoe crab (Limulus polyphemus). News reporting has called the species “heroes of modern medicine,” and even as doctors were scrambling to offer a COVID vaccine, it was a mysterious element from horseshoe crab blood that drew attention for making those vaccines safer; a natural history museum called it the “miracle vaccine ingredient.”
The discovery goes back to the 1960s when scientists found an ingredient in the blue, copper-based blood of horseshoe crabs that has since helped doctors ensure the safety of medical devices and injectable liquids by detecting even minute amounts of contamination. It turns out that the curious helmet-like creatures that will be crawling onto local beaches for spawning season through the end of June have something in their blood that saves lives.
The medical product of horseshoe crab blood, called limulus amebocyte lysate, has been the gold standard for detecting bacterial toxins for decades – but not without a toll on the number of crabs. The Center for Biological Diversity estimates that 1.1 million horseshoe crabs along the Atlantic coast are harvested by the biomedical industry each year, sending them to labs where as much as 30 percent of each animal’s blood is drained, while still alive, before returning them to the wild. A worrying recent study suggests that as many as 30 percent of horseshoe crabs do not ultimately survive the process.
At the same time, more than 700,000 horseshoe crabs are also being harvested along the Atlantic coast each year as bait for eel, conch and whelk fisheries. Research in 2022 out of Connecticut’s Sacred Heart University, an anchor institution for Project Limulus in our area, noted that a combination of overharvesting, pollution, climate change and habitat loss have all led to the depletion of the species in the Long Island Sound and decreased the role of the species in the region’s ecosystem to the point where they are “functionally extinct.”
There is hope in the supportive role that state and local policies are establishing for horseshoe crab survival, and even restoration, in Connecticut. It may be that during this spawning season, though, the most directly helpful measures can be offered by those beachfront communities that can serve as hosts to this remarkable species.
For some starter trivia on the Limulus polyphemus, consider the following:
1. The horseshoe crab species is not technically a crab. According to scientists it is more closely related to:
a) spiders
b) armadillos
c) turtles
2. True/False: Horseshoe crabs have existed on the Earth since before the first dinosaurs.
3. Choose the correct word: While helping an upended, still living, horseshoe crab back into the water, a person should (always/never) pick the animal up by its tail.
4. True/False: Horseshoe crabs outgrow their shells an average of 16 times before they reach maturity.
5. Which two of the following states have established a year-round ban on the capture of Horseshoe crabs for bait?
a) Connecticut
b) New York
c) New Jersey
6. True/False: In its permits to beach organizations, Connecticut prohibits the mechanical raking of sand, deeper than two inches, between May 10 and July 15.
7. True/False: The biomedical companies that run labs for extracting horseshoe crab blood are strictly regulated to ensure humane practices.
8. True/False: The only substance that drug companies find acceptable for detecting bacterial endotoxins today is LAL (derived from horseshoe crab blood).
Answers:
1. a. The horseshoe crab is most closely related to the arachnid family, which includes spiders, ticks and scorpions.
2. True. Horseshoe crabs have been on the planet, with very little variation in appearance, more than 450 million years.
3. Never. Wildlife experts say a horseshoe crab can be injured if someone tries to pick it up by the tail. If the animal has been flipped over by a wave experts suggest gripping it at the widest part of the shell and gently carrying it to water or replacing it on the ground that way.
4. True. Beach walkers may fret over the strangely empty shells that can litter the shoreline, but horseshoe crabs, who live to an average of 20 years, grow out of their shells several times before reaching full growth at around 10. The process of shedding the old and growing new shells, in this case, is called molting.
5. a. and c. Connecticut banned all harvesting of horseshoe crabs for bait fishing as of October 2023, and New Jersey enacted a similar ban in 2008. New York restricts the capture of horseshoe crabs for bait only during certain spawning periods.
6. True. The goal of restricting machine raking of sand during this period, says the state Department of Energy and Environmental Protection, is to protect spawning horseshoe crabs.
7. False. According to Larry Niles, biologist and co-creator of the Horseshoe Crab Recovery Coalition, the bleeding industry is completely unregulated. Reformers urger closer attention to the animal’s welfare as part of more sustainable approaches to utilizing the “miracle vaccine ingredient.”
8. False. Happily for the future of horseshoe crabs, a few synthetic (lab-made) alternatives to LAL, including one made from cloning the element from crab blood, are gaining acceptance among pharmaceutical groups.