Beach nesting bonanza! Help us by reporting tagged horseshoe crabs

Florida Horseshoe Crab Watch is a citizen science program focused on collecting important data on nesting horseshoe crabs. Tagging and releasing horseshoe crabs is an important duty of the citizen scientists, as is reporting later sightings of tagged crabs. The program, coordinated jointly by the Florida Fish and Wildlife Conservation Commission (FWC) and the University of Florida IFAS Extension, needs help from the public to increase reports of tagged horseshoe crabs on Florida’s beaches. Read on for more on how you can help!

Volunteers taking measurements on horseshoe crabs Why study the crabs?

Horseshoe crabs are ecologically important, especially for shorebirds. Many marine species eat horseshoe crabs and their eggs. Shorebirds such as red knots depend on the eggs for energy during migration. Horseshoe crabs are used as bait (conch and eel fisheries) and are captured live for display in aquaria and for research. Importantly, the special blue blood of horseshoe crabs is vital for medical testing. The FDA requires that all injectable medicines, devices used for injection, and internal prosthetics (e.g., heart valves) undergo testing with an extract only found in horseshoe crab blood (Limulus Amebocyte Lysate). If you have ever received a vaccine, horseshoe crabs have helped you!

Their importance in different industries means that there is a demand for wild-caught horseshoe crabs. A moderate fishery for these animals exists in Florida. The FWC is required to collect data on fisheries within the state, but limited resources prevent detailed surveys from being completed by state biologists. Therefore, citizen scientists are providing an important service by helping the state keep track of population numbers and better manage these important marine animals, to ensure that the ecological function of horseshoe crabs is not impacted negatively by harvest.

tagged horseshoe crabsWhat can you do?

Keep your eye out for tagged horseshoe crabs the next time you are walking the beach or near the water. You are especially likely to spot nesting horseshoe crabs during the fall and spring during extra high tides. These higher tides, called “spring tides” occur around when the moon is either full or new.

If you see a tagged horseshoe crab, alive or dead, you can really help our data collection efforts by reporting the tagged animal. To report a tag, follow the instructions below. You can download the picture to your phone so you will always have the information. Snap a picture of the tag or record the number on the tag. Try to limit disturbance to the crab. Try not to pick it up and if you must pick it up, NEVER pick it up by the tail. Please DO NOT remove the tag unless the crab is dead. Make a note of the date and time you saw the crab and the location.

How to report a tagged horseshoe crab

You can report this data using the online form at ( or by calling 1-888-546-8587 (1-888-LIMULUS). This data goes into a national database maintained by the US Fish and Wildlife Service and contributes to knowledge about horseshoe crab movements and population numbers.

If you would like information about how you can be involved in the citizen science surveys, please contact me!



Posted: March 4, 2019


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