Spawn of the Horseshoe Crabs!
by Evelyn Maguire
From mid-May to mid-June, some of the oldest (and strangest) Delaware Bay residents overtake the beaches in fantastic numbers. No, I’m not talking about New York tourists, but rather the enigmatic horseshoe crabs — mysterious invertebrates that visit Cape May and surrounding areas each year to spawn. The march of the horseshoe crabs onto the shore is an ancient spectacle, and one that plays an ever-important role in maintaining the ecological balance of the Delaware Bay.
Though called crabs, the horseshoe crab is more closely related to a scorpion or the now-extinct trilobite, and has not changed much in 300 million years, making the species older than dinosaurs. Ten legs, a long spiny tail (called a telson), and a hard shell can make the horseshoe crab look intimidating (or like a Pokémon), but in fact, the horseshoe crab does not sting, pinch, bite, or otherwise cause trouble to people. The spiny tail is used to help the horseshoe crab flip right-side-up if the tide turns it on its back, though a helping hand from a passerby is more than welcome. And much like many Cape May visitors, the horseshoe crab has a particular fondness for fresh clams.
During this time of the year, tens of thousands of horseshoe crabs rendezvous to mate and lay millions of eggs under the moonlight. According to Lisa Ferguson, the Director of Research and Conversation at the Wetlands Institute, horseshoe crab eggs are a vital food source for fish, reptiles, and birds alike, and are a significant reason as to why Cape May is a resting spot for so many migratory birds. Shorebirds such as the red knot, ruddy turnstone, and sandpiper rely almost exclusively on a diet of horseshoe crab eggs — as their early summer arrival means there are not yet enough insects to sustain their population.
As such, it is incredibly important to both track the horseshoe crabs’ population as well as to lend a helping hand to those crabs who find themselves upside-down. Spawning surveys, such as the Delaware Bay Horseshoe Survey, are in need of volunteers to aid in the tracking and counting of the horseshoe crab population. For a more hands-on volunteering experience, visitors and locals can check out Return the Favor, a multi-partner program working to help stranded or overturned horseshoe crabs. “We love making those opportunities available for those who are visiting,” says Ferguson. “Volunteers are really the soul and foundation of the program. This is Return the Favor’s 10th year — we’re hoping to reach our goal of one million crabs helped this year.” The program currently has helped over 800,000 horseshoe crabs!
To learn more about Cape May’s diverse ecology, join Cape May MAC for a Natural Histories trolley tour! On Wednesday mornings from June 1 to October 5, Cape May Bird Observatory naturalists will introduce visitors to Cape May’s world-famous birdwatching, monarch migration, natural history, and more.
To learn more about horseshoe crab volunteering opportunities, visit https://www.delawarebayhscsurvey.org/ and https://returnthefavornj.org/. And a special thank you to local, horseshoe-crab-fanatic Katie O’Neil for providing the photos you see here!