WE ARE ALL LINKED WITH LIMULUS
WE ARE ALL LINKED WITH LIMULUS!
Horseshoe crabs (Limulus polyphemus) are a common sight on sandy beaches and other nearshore habitats in Florida. Horseshoe crabs are important for several reasons. Many marine species eat horseshoe crab eggs, the crabs serve as bait (conch and eel fisheries) and they are captured live for display in aquaria and research. In addition, the blood of horseshoe crabs is vital for biomedical testing – the FDA requires that all injectable medicines, devices used for injection, and internal prosthetics undergo testing with an extract only found in horseshoe crab blood (Limulus Amebocyte Lysate).
If you have ever received a vaccine or had a surgery, horseshoe crabs have helped you!
Horseshoe crabs are different from most other invertebrates in that they take a long time to reach maturity – about 10 years on average. Their longer lifespan and complex life history puts them at potential risk for over-exploitation. Therefore, the small fishery for horseshoe crabs in Florida must be managed to ensure the ecological functions of the horseshoe crab are sustained. Smart fisheries management requires reliable data on population numbers.
FUN FACT: Horseshoe crabs are ancient organisms – they have been in existence for hundreds of millions of years! This is much longer than the average lifespan for a species on Earth and, therefore, horseshoe crabs are considered living fossils.
Horseshoe crabs mate along beaches, especially during full and new moons of the spring (Mar-Apr) and fall (Sept-Oct) months. This behavior makes study of population numbers convenient but no consistent scientific studies have been conducted here in Florida because the Fish and Wildlife Conservation Commission (FWC) lacks the staff to collect enough data to monitor populations across the state.
“I enjoyed participating in the survey and feel that it is very worthwhile. I felt it helped to educate the public about horseshoe crabs… Its scientific worth is also very valuable.”
Volunteer, Florida Horseshoe Crab Watch, Cedar Key
Enter: Citizen Scientists
The Florida Fish and Wildlife Conservation Commission is required to collect data on fisheries within the state, but limited resources prevent stare biologists from conducting detailed, statewide surveys. Therefore, citizen scientists are providing an important service by helping the state keep track of population numbers and better manage these important marine animals, ensuring the ecological functions of horseshoe crabs remain intact.
Volunteers walk a known section of beach at predetermined times and count the number of horseshoe crab mating groups observed. A subset of the crabs are collected, tagged with a small, numbered disc, and released back to the wild. Reports of tagged horseshoe crabs help track crab movements, reappearances on beaches, and population numbers.