A ritual dating back millions of years takes place again this spring on Florida beaches. Spring marks horseshoe crabs’ mating season, and biologists with the Florida Fish and Wildlife Conservation Commission want the public’s help identifying spawning sites.
Beachgoers will likely have the best luck spotting mating horseshoe crabs around high tide, just before, during or after a new or full moon. The conditions around the full moon this Sunday, March 16, and the new moon on March 30 will create ideal opportunities to view the spawning behavior of horseshoe crabs.
Mating crabs “pair up,” with the smaller male on top of the larger female. Other male crabs may also be present around the couple. Beachgoers lucky enough to spot horseshoe crabs are asked to note how many they see and whether the horseshoe crabs are mating. If possible, the observer should also count how many horseshoe crabs are mating adults and how many are juveniles (4 inches wide or smaller).
In addition, biologists ask observers to provide the date, time, location, habitat type and environmental conditions – such as tides and moon phase – when a sighting occurs.
The FWC asks the public to report sightings through one of several options. Go to the FWC website, click on "Horseshoe Crab Nesting Activity” for the “Submit a Horseshoe Crab Survey” link, then select “Florida Horseshoe Crab Spawning Beach Survey.” You can also report findings via email at horseshoe@MyFWC.com or by phone, 866-252-9326.
The survey program began in April 2002. Through 2013, the FWC received 2,831 reports from across Florida.
Horseshoe crabs, often called “living fossils,” are an important part of the marine ecosystem. Their eggs are a food source for animals. Birds, such as red knots, rely on horseshoe crab eggs to fuel their long migrations to nesting grounds.
Horseshoe crabs have also proved valuable to human medicine. Pharmaceutical companies use horseshoe crab blood to ensure intravenous drugs and vaccine injections are bacteria-free and sterile. Scientists are also using horseshoe crabs in cancer research.