Title: The Vital Role of Horseshoe Crabs in Modern Medicine
Subtitle: Horseshoe crabs provide a unique lifeline for medical advancements through their incredible blue blood
By Helen Sullivan
Every day, in laboratories around the world, horseshoe crabs undergo a fascinating and indispensable process that makes them a significant player in modern medicine. Strapped into specially designed harnesses, these prehistoric creatures are drained of a third of their blood, which plays a critical role in ensuring the safety of medicines. Once the procedure is complete, these enigmatic creatures are returned to their natural habitats to continue their aquatic livelihoods.
Horseshoe crabs, known scientifically as Limulus polyphemus, resemble a fossilized Roomba that has devoured a stingray. With a size of around 20 cm and twice that length including their tails, these ancient creatures seem better suited for museum dioramas rather than the clinical rooms where they undergo their life-saving procedure. Their rightful places are dusty papier-mache replicas of rocks or captured forever in solid resin water, rather than being meticulously arranged in rows within steel-filled rooms.
However, when their shells are wet, revealing their true form up close, it becomes apparent that these creatures remain very much alive. Their crackled shells exhibit a mesmerizing dark olive hue, akin to an old painting. But it is their blood that holds the true marvel. Exhibiting a striking milky blue color, horseshoe crab blood has the remarkable ability to rapidly and accurately detect toxins that may contaminate medicinal products. Consequently, approximately half a million horseshoe crabs are annually caught and bled in laboratories.
The procedure involves injecting a needle through a hinge in the crab’s shell, reaching a membrane running along its caterpillar-shaped heart. Deborah Cramer, an author who has extensively researched horseshoe crabs, explains that anyone who receives a flu shot, a COVID-19 vaccine, childhood immunization, heart stent, or hip replacement is ultimately protected by a test that utilizes the blue blood of these remarkable creatures.
Beyond their role in medicine, horseshoe crabs also capture our fascination during their extraordinary annual spawning event. Spanning thousands of kilometers, millions of crabs gather at beaches during full moon and high tide, with females scaling the shore while the attached males trail behind. This remarkable ritual has been ongoing since prehistoric times, long before dinosaurs roamed the Earth. The sight of these creatures huddled together appears like hundreds of discarded army helmets on the sandy coastline. However, beneath the surface, when a wave flips one over, the mesmerizing sight of legs rhythmically flailing in the moonlight emerges.
Examining the eggs laid during this magnificent spawning event, magnification reveals transparent orbs dotted with tiny green creatures. These small beings, gently cocooned within their convex shells, joyfully somersault against the concave walls of their temporary home. Oblivious to the epoch they were born into, these remarkable creatures face encounters with modern-day challenges, including vampires, and yet, remarkably, most of them survive.
As we marvel at the crucial role horseshoe crabs play in modern medicine and their enduring presence throughout the ages, it is essential to recognize the symbiotic relationship between these captivating creatures and the many lives they ultimately touch. They remind us of the delicate balance between nature and technological advancements, enabling us to appreciate the profound impact of these ancient beings on our modern world.
Helen Sullivan is a Guardian journalist. Her first book, a memoir titled “Freak of Nature,” will be published in 2024.
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