Long Island Mammal Survey
About Horseshoe Crabs
Horseshoe crabs (Limulus Polyphemus) have been around practically unchanged for over 450 million years, categorizing it as a “living fossil”. These fascinating creatures aren’t actually crabs at all, as they don’t fall under the subphylum “crustacea,” which includes blue crab, spider crabs and other true crabs. They can be found in tidal and subtidal communities all over Long Island inhabiting both brackish and marine waters. They are easy to distinguish by their long slender tail and uniquely shaped large brown shell. Horseshoe crabs prefer muddy bottoms that they can push through, feeding on marine invertebrates.
During the months of May and June, adult horseshoe crabs travel up towards the shoreline to spawn. This is typically in conjunction with the spring tide, the highest tide of the month. Various shorebirds, turtles, and fish feed off of horseshoe crab eggs. Horseshoe crabs themselves are used for bait by commercial fishers and in the past have been over-harvested leading to a plunge in populations. This alongside habitat destruction have been major factors in their decline.
Each summer Seatuck conducts the NYSDEC survey at Captree State Park to monitor our local populations of horseshoe crabs. The information collected is crucial in protecting these populations. To learn more about how you can join the effort, visit our horseshoe crab citizen science page