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Crab discovery at Bald Point could aid vaccines

Chester Butler Special to the Times
The Apalach Times

Volunteer citizen scientists conducting a routine spawning survey of horseshoe crabs at Bald Point State Park made a surprising discovery in October 2019. They found a living coral attached to a horseshoe crab’s shell or carapace. This is the first report of a coral using a horseshoe crab as a host.

In scientific circles this is a big deal. It is not unusual to find barnacles, muscles, algae, limpets and even oysters growing on the shells of horseshoe crabs. All these animals can stand variations in temperature and salinity; corals are much more sensitive and usually do not survive in a changing environment.

Horseshoe crabs are mobile and are known to travel 55 miles or more. And the ride on a horseshoe crabs’ back is not first-class accommodations for a coral. As the crabs travel, they root the Gulf bottom for food and are buffered by strong currents. They endure changes in water temperature, move in and out of salinity zones and leave the water to spawn on beaches. A coral must have stable conditions to survive and grow. A coral larva that attaches to a horseshoe crab is not in for a dream vacation tour.

So, scientists wonder, how did this coral survive? Is this coral different from others of its species? Did the host crab stay in one area allowing the coral to grow? Do some crabs travel and some do not? If so, why?

Two released tagged horseshoe crabs

You may be wondering why this discovery is important? Good question! It could be that your life may depend on the answers to these questions about horseshoe crabs and coral. Frankly, your life may have already been saved by a horseshoe crab! Here’s a short explanation.

The crab’s bright blue blood is used to test vaccines for endotoxins, which can make you sick and cause death from septic shock. Testing a vaccine batch to make sure no endotoxin potential exists is a way to assure a vaccine is safe. The horseshoe crab is getting a lot of press lately due to the rush to find a COVID-19 vaccine. No horseshoe crab, no safe vaccine. It is that simple. (Cue applause for the horseshoe crab’s donation to human health!)

There is no biomedical collection program in Florida. The data collected by Florida Horseshoe Crab Watch is used to make sure the horseshoe crab population is stable and stays that way. So, the more we know about these crabs, the more likely we are to be able to stop what appears to be a worldwide decline in their population.

The volunteer citizen scientists who made this new discovery are from Franklin, Wakulla, and Leon counties. You’ll find them walking the beaches at Bald Point in the spring and fall when horseshoe crab mating is at its peak. They weigh, measure, age, record the sex and tag the crabs. They also record any injury and note any hitchhiking animals attached to the crab’s shell. All this information is reported to scientists at the Florida Fish and Wildlife Conservation Commission, the University of Florida and many others working on understanding the horseshoe crab. This research is important because for now. there is no other safe way to test vaccines for the deadly endotoxins.

Chester Butler is a Franklin County Green Guide and a University of Florida Master Naturalist. He is also a four-year veteran of the FWC Horseshoe Crab citizen scientist program in Franklin County. He can be contacted at You can find out more about the horseshoe crab FWC project and how to be a volunteer citizen scientist by contacting Berlynna Heres at .