Cornell Cooperative Extension Horseshoe Crab Monitoring

The DMEA participates in the NYS DEC/Cornell University Cooperative Extension Horseshoe Crab Monitoring Program in Little Neck Bay. A group of hearty local environmentalists count horseshoe crabs at Douglas Road and Bayview Avenue, at the Manor Dock and at Parson’s Beach, on the new and full moons in May and June every year. Braving winds, phragmites, slippery shorelines, high tides and raccoons, the Monitoring Team measures, tags and records horseshoe crabs. Individual data about size, sex, location and condition helps to inform our understanding of horseshoe crab growth, spawning and migration patterns up and down Eastern coastal waters of the US.

In 2020, the team counted more than 230 horseshoe crabs! They were able to tag 25 Males and 2 Females for a total of 27 tags. The team found two horseshoe crabs that had previously been tagged. These tag numbers were recorded and sent to the Horseshoe Crab Monitoring Program for study. All of these ancient arthropods were left undisturbed to spawn another day.

Horseshoe Crabs are not true crabs, even though they use their 5 pairs of legs to creep along the sandy or muddy sea floor. Limulus Polyphemus, as they are known, are more closely related to spiders! They have a hard exoskeleton and blue blood. There is evidence that Horseshoe Crabs are millions of years old – even older than dinosaurs! Individuals may live 40 years or more.

Horseshoe Crabs face a number of challenges to their survival. Horseshoe crab hatchlings, which look like tiny versions of adults, are a delicacy for migrating birds who time their migration around horseshoe crab spawning. Although people don’t eat horseshoe crabs, the arthropods have been used as bait in commercial fishing. Shoreline changes, watershed development, storm run-off, trash and natural adaptation to the environment all impact horseshoe crab survival. The Horseshoe Crab Monitoring Team was astounded at the amount of discarded plastic at the collection sites. At times, the floating bags and other debris completely obstructed visibility.

Horseshoe crabs are extremely important to the biomedical industry. Their unique copper-based blue blood contains a substance called "Limulus Amebocyte Lysate" or "LAL". It is used to test for sterility of medical equipment and virtually all injectable drugs since the LAL compound coagulates when small amounts of bacterial toxins are present. Anyone who has had an injection, vaccination, or surgery has benefited from horseshoe crabs! To collect the blood, horseshoe crabs are gathered and brought to a biomedical facility where blood is drawn and sent to processing for extraction of LAL. Horseshoe crabs are not harmed during this process. They are returned to their habitats. In addition, research on the complex, compound eyes of horseshoe crabs has led to a better understanding of human vision.

The Horseshoe Crab Monitoring Program provides data collected throughout the horseshoe crab habitat that is crucial to track changes to migration and spawning patterns and to the survival of this amazing species. If, like the DMEA, you have fallen in love with horseshoe crabs, consider the purchase of a DMEA Horseshoe Crab mug via the Support Us page!