One of the shoreline ecosystem’s most critical species has been on a steady and concerning decline for decades. Don’t call it a crustacean, the rather weird, alien-looking arachnid is not only a critical food source for numerous marine and bird species but it is crucial to a wide variety of biomedical research and uses, including those that help save lives.

According to volunteer for Project Limulus and their Guilford Beach Captain, Deanna Broderick, it’s important to take steps now to halt the decline of the species and to reestablish its habitat. She says recent studies indicate its population is continuing to decline. These “living fossils” are among the planet’s oldest organisms, having outlasted dinosaurs and surviving through numerous extinction events.

“The hand harvest of the breeding population is a major cause of population decline in the Sound. Even though only 12 permits exist to harvest horseshoe crabs and the reported catch is low, thousands of additional crabs are harvested every spawning season illegally, (that’s from) personal observation and observations reported by citizen scientists of Project Limulus,” said Broderick. “Other stressors include loss of habitat both marsh, which are the nurseries for young crabs, and sandy areas; pollution, bycatch in ghost nets and abandoned lobster traps as well as entrapment in intake pipes of powerplants.”

The species is not only important to the ecosystem, they are actually a living ecosystem themselves, according to Broderick.

“Horseshoe crabs are ‘living fossils,’ they have existed nearly unchanged for at least 445 million years, well before even dinosaurs existed. Despite existing for hundreds of millions of years, horseshoe crabs are nearly identical to their ancient relatives,” said Broderick. “Horseshoe crabs are themselves environments. Scuds, ghost anemones, asteriids, snail furs, blue mussels, barnacles, sea strawberries, seal lettuce, red beard sponges, eastern oyster, northern rock barnacles, skeleton shrimps, sand builder worms, bushy bugulas, hard tube worms, flat worms, oyster drill eggs, and Agardh’s red seaweed all make the carapace of the horseshoe crab their home.”

Broderick volunteers with Project Limulus helping gather data on horseshoe crabs, which included tagging programs, that monitor the species. The data appears to indicate the problem only appears to be getting worse.

It takes nine to 11 years before horseshoe crabs are fully-grown and sexually mature, they will molt 16 to 17 times. They are very vulnerable when they first molt and need a “safe” place to wait for their new shell to harden, said Broderick.

According to Broderick, in late spring and early summer horseshoe crabs arrive on area beaches en masse to lay their eggs. The peak spawning period on the Atlantic Coast is May through June, which is why Guilford is among a growing number of towns that do not use beach cleaning devices below the tide line in order to protect the area of the beach where these crabs lay their eggs.

These creatures were once a critical part of the ecosystem and their declining numbers have affected numerous species, Broderick said.

“Horseshoe crabs are part of the food web, migratory shorebirds rely on the eggs of horseshoe crabs for food. Unfortunately, in Connecticut the population density does not allow for the Horseshoe crab to function within the food web as they have in the past. They are no longer a source for shorebirds and fish in Long Island Sound due to their low numbers,” said Broderick.

According to Broderick, all of us benefit from the horseshoe crab, whether we know it or not. Their blood is utilized by the biomedical industry to produce a widely used test for the presence of endo toxin in vaccines, including the COVID vaccine. Their benefit to humans doesn’t end there.

“Extensive research has been conducted on horseshoe crabs with respect to their eyes and vision. This research has resulted in important findings pertaining to the manufacture of surgical sutures and development of dressings for burn patients,” said Broderick.

So, what can residents do to help?

Broderick said that the best thing to do to protect the species is to leave the crabs alone. Unless they look like they are in obvious distress, or are struggling on their backs, just letting them develop and breed is an effective way to be part of the solution.

“When you see a horseshoe crab that is stranded upside down on the beach, just flip them over. It is important not to flip them by their tail, however. Even though it looks scary, the tail is very delicate and can be easily damaged. The best way to turn them over is by the edge of their shell, the horseshoe crab doesn’t bite or sting the claws are very gentle and won’t hurt you. If you suspect illegal harvesting of horseshoe crabs report it to the environmental conservation tip line, 860-424-3333,” Broderick said. “Support legislation that will prohibit the harvesting of Horseshoe crabs for bait. Encourage your community to not rake or groom the beach below the high tide line during Horseshoe Crab spawning time, mid-May, June and early July. Grooming or raking the sand will dislodge the Horseshoe Crab eggs.”

A Few Fast Facts About Horseshoe Crabs

*Horseshoe crabs do not have teeth and don’t bite

*Their tail does not sting, it is designed to allow them to re-right themselves when flipped on their back, but it can scratch so be careful

*Don’t pick up horseshoe crabs by their tails. Their tails are actually quite fragile and if damaged that individual is probably doomed

*This species does not reach sexual maturity until they are approximately 11 years old, so protection is vital to their survival

*If you find a crab with a tag, follow any instructions on it and report your find immediately

*Habitat destruction is a main factor in their decline, but their use as bait for commercial fisherman also has an adverse effect on the species.

*Anyone wishing to legally take horseshoe crabs for fishing needs to review the new laws concerning the dates and the limits imposed on the species. Contact the state Department of Energy & Environmental Conservation site for all of the relevant info

*A fully adult female will lay 60,000 to 100,000 eggs, but only one of those will reach the age to reproduce again

*These crabs are among several species that are affected by light pollution, so turn down or turn off lights, especially anything that shines directly at or on the water. Light negatively impacts numerous species as it can confuse animals, especially juveniles.