HORSESHOE CRAB SHELLS ARE WASHING UP ON LOCAL BEACHES. HERE’S WHY:

VIRGINIA BEACH — With pointy-edged shells and spiky tails, horseshoe crabs have existed since before the dinosaurs and look more intimidating than most sea creatures that wash ashore in Virginia Beach.

Never fear — they’re harmless, and the ones strewn along the North End’s shoreline this week are a sign of life, not of death. They’re the remnants of horseshoe crabs that have molted.

Dozens of greenish-brown shells, each about the size of a large hand, sat motionless in the wet sand Friday morning, north of 60th Street. Some of them languished upside down, with pairs of legs and gills still attached and facing skyward.

Horseshoe crabs are an ancient species that are more closely related to spiders and scorpions than crabs. They grow larger by shedding their old shell.

Juveniles molt several times during the first few years of life. Adult horseshoe crabs shed their shells annually, until they reach sexual maturity, according to Maryland Department of Natural Resources.

Atlantic horseshoe crabs, also known as limulus polyphemus, are bottom-dwelling arthropods that are found from Maine to the Gulf of Mexico, but are most abundant from New Jersey to Virginia. They live up to 20 years.

Adult horseshoe crabs spawn in the spring at high tide under full or new moons. Birds and fish feed on their eggs. In the fall, they move to deep bay waters or migrate to the Atlantic continental shelf, according to Virginia Institute of Marine Science.

Autumn storms churn up the bottom of the Chesapeake Bay and the ocean, and their empty shells wash ashore. On Monday morning, the helmet-like exoskeletons speckled the sand at the

North End.

More of them could wash up over the next several weeks, depending on the winds and tides.

Horseshoe crabs have made headlines recently related to the coronavirus pandemic. Their blood is bright blue and contains a chemical that protects it from bacteria.

It’s used to test the safety of medicines, vaccines and medical devices and will likely be used in testing vaccines for COVID-19, according to reports.