Beachgoers can help biologists learn about spawning horseshoe crabs

May 3, 2011

Horseshoe crabs gather at Phillippe Park, Safety Harbor. (FWC photo)

Be a part of science and report spawning horseshoe crabs

This spring, mating horseshoe crabs will gather at sandy beaches throughout the state. Biologists with the Florida Fish and Wildlife Conservation Commission’s (FWC) Fish and Wildlife Research Institute need help from the public to identify horseshoe crab spawning areas.

The best time to find spawning horseshoe crabs is around high tide, just before, during or after a full or new moon. The new moon conditions around May 3 and the full moon conditions around May 17 will create good opportunities for viewing the spawning behavior of horseshoe crabs.

The FWC asks beachgoers to report the number of horseshoe crabs they see and whether the horseshoe crabs are mating. Mating crabs “pair up,” with the smaller male on top of the larger female. Other male crabs may be present around the couple. Biologists also want to know the date, time, location, habitat type and environmental conditions, such as tides and moon phase. If possible, specify roughly how many are mating adults and how many are juveniles (4 inches wide or smaller).

FWC asks people to report sightings through one of several convenient options. Go to and follow the link to fill out an online survey; email findings to; or call the FWC at 866-252-9326.

Horseshoe crabs have been around for approximately 450 million years and are an important part of a marine ecosystem. Their eggs are a vital food source for animals and birds, such as the red knot.

Horseshoe crabs are important to humans as well. For instance, in the biomedical industry, horseshoe crab blood helps save human lives. Pharmaceutical companies use horseshoe crab blood to make sure that intravenous drugs and vaccine injections are bacteria-free. Also, research into horseshoe crab eyes has given scientists a greater knowledge of the functioning of human eyes.