Remarkable “Marine Spider”
While not universally famous like Spider-Man, there’s another sort of superhero on planet earth today, saving lives around the world. And this creature can sometimes be seen at the beach, right here on Amelia Island. So valuable to mankind, its blue blood is reportedly worth a whopping $60,000 a gallon.
A type of “marine spider,” this remarkable creature is odd-looking, but often ignored by beach goers. Most know this seashore superhero as the horseshoe crab. But, they’re not true crabs. They’re arthropods, more closely related to spiders, scorpions and ticks.
Why is horseshoe crab blood worth so much? Because there’s something extraordinary about it (besides its blue hue), utilized in the biomedical industry. Mankind around the globe relies on it. These crabs, instrumental in saving lives around the world, however, are in growing need to be saved themselves. Here in Florida, the state needs much more data on horseshoe crabs. Read more further below about efforts to collect data, including a tagging program locally at Fort Clinch State Park.
It’s probably safe to say hundreds of millions of people have been benefactors (many unwittingly), of horseshoe crab blood. Many of whom have never even seen a horseshoe crab, have been protected by a wondrous substance in its blood, LAL (limulus amebocyte lysate).
Horseshoe crab blood is used to test potential contamination during the manufacture of what goes in our bodies. LAL clots when certain bacterial toxins are present. If you’ve had injections of medicine and/or vaccines (and/or IV drips), the process was made safer thanks to horseshoe crabs. And those with implanted devices have also benefited (such as knee replacements, artificial hips, or a pin holding a broken bone, for example).
Take a look at this video by Charles River Laboratories that explains more about the biomedical industry process of harvesting horseshoe crabs temporarily, extracting blood, then returning them to the water.
Birds Depend On Them
The crabs are not just important to people. Shorebirds depend on the species for sustenance. The eggs of horseshoe crabs are a main source of food for migratory birds, particularly Red Knots. The eggs are “tiny, pearly, green or pink,” according to NOAA Fisheries. Read related article, “Horseshoe Crabs: Managing A Resource For Birds, Bait and Blood.”
Often, it’s horseshoe crab shells (the hard exoskeleton) that local beachcombers see washed up along the shoreline. To grow, the crab molts its shell. However, if you see Florida horseshoe crabs spawning (or a tagged horseshoe crab), please report the sighting. The state of Florida needs the data.
How To Report Sightings
How do you know if they’re spawning? If you observe two or more connected together, report it! Pictured below are spawning crabs seen at Fort Clinch. According to FWC, “When mating, the smaller male crab attaches himself to the top of the larger female’s shell.”
When Do They Spawn?
According to the Florida Fish and Wildlife Conservation Commission, “Horseshoe crabs can nest year-round in Florida, with peak spawning occurring in the spring and fall. When mating, the smaller male crab attaches himself to the top of the larger female’s shell by using his specialized front claws, and together they crawl to the beach… Most of this nesting activity takes place during high tides around the time of a new or full moon.”
To report sightings of spawning crabs, go to the “Florida Horseshoe Crab Spawning Beach Survey” link. The FWC Reporter app is free to download on Apple or Android smartphones or tablets from the App Store and Google Play. You can also report findings via email to: [email protected] or by phone at 866-252-9326.
Crabs Tagged At Fort Clinch
On Amelia Island, a new horseshoe crab monitoring program was initiated in 2018 with volunteers observing, tagging and recording data at Fort Clinch State Park. The Fort Clinch project is part of a much bigger effort statewide to collect data about the species. Horseshoe crabs are reportedly declining in number in their ranges. Florida needs much more data on horseshoe crabs. (To be clear, crabs are monitored, not “harvested,” locally.)
Report Tagged Crabs
Citizen Science Project
The FWRI and the University of Florida began a citizen science program a few years ago to train volunteers to assist in monitoring horseshoe crab population in the state of Florida. Watch this video below to learn more about what’s entailed in the monitoring program, especially if you may be interested in participating as a volunteer.
There are areas in the USA with heavy concentrations of the crabs. The Delaware Bay region has the highest population of horseshoe crabs in the world, and this is a key harvest area.
The “Atlantic States Marine Fisheries Commission Horseshoe Crab Fisheries Management Plan” went into effect about 18 years ago. Management practices led to decreased harvesting of the crabs over time. While back in the late 1990s, over 2 million horseshoe crabs were harvested annually, the harvest has been reduced in more recent years. About half a million were harvested in the year 2018.
Concern For Species
Unfortunately, there’s a cost to the horseshoe crab species during the harvesting and lab process. While estimates vary, somewhere between 15% to perhaps 30% of the crabs don’t survive long-term after the blood extraction process. The loss of crabs after the process raises concern for the species. According to the FWC, “horseshoe crabs are declining in number throughout their range due to a variety of factors.” Already developed is a synthetic alternative to crab blood for endotoxin detection. Future demand for horseshoe crab blood in the biomedical industry may be reduced if alternative methods are adopted on a larger scale.
To learn much more about the amazing horseshoe crab, also visit the Florida Fish and Wildlife page with more facts about this species.