How About Those Horseshoe Crabs!

Horseshoe crabs have survived for 450 million years and five mass extinctions - but current practices put them at risk. Mass Audubon's Mark Faherty shares efforts to protect these remarkable creatures during spawning season.

What are horseshoe crabs?

09.26.24 — WELLFLEET, MA — Horseshoe crabs have survived for 450 million years and five mass extinctions, making them true "living fossils." These "living fossils" have remained remarkably unchanged in appearance and behavior, making them a significant link to Earth's prehistoric past. In addition, these marine arthropods play a vital role in maintaining the health of coastal ecosystems.

What do horseshoe crabs need today?

Mass Audubon's Science Coordinator Mark Faherty says the organization has been working to protect these remarkable creatures during spawning season as well as helping create a better understanding of them and their vital place in our ecosystem.

"What would a horseshoe crab say if you asked it what it needed ? They would say 'we need to be able to spawn without being harvested and put in a freezer to be put in a whelk pot," he said, explaining that working to ban horseshoe harvest for bait is among the organization's efforts on behalf of the species.

What roles do horseshoe crabs play in the Cape Cod ecosystem?

 On Cape Cod, horseshoe crabs are most visible during their spawning season, which typically occurs in the spring. Faherty says horsehoe crab eggs are not only essential for the next generation of crabs but also serve as a critical food source for migratory shorebirds, as well as species like logerhead turtles. This interconnection highlights the importance of maintaining healthy populations of horseshoe crabs to sustain broader ecological relationships.

What role do horseshoe crabs play in human health?

Beyond their ecological role, horseshoe crabs have a direct impact on human health. Their blue blood contains a substance used in medical testing to ensure the safety of vaccines and medical devices by detecting bacterial contamination.

What puts pressure on horseshoe crabs?

Despite their ancient history, modern threats could end millions of years of survival.  Over-harvesting and habitat loss form two key pressure points on horseshoe crab populations. The dramatic impact of these threats and the drop in their numbers has prompted conservation efforts like those on Cape Cod.

Do conservation efforts work?

Faherty said conservation efforts can and have worked. For example In locations like as the Monomoy National Wildlife Refuge that ban harvesting and protect habitat, the populations of both horseshoe crabs and sea birds have rebounded. 



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