The magic elixir is extracted from over 600,000 “donors” every year, each of whom parts with 30 percent of its blood before being released within 48 hours. To ensure that a vaccine or injectable drug is safe, they introduce horseshoe crab amebocytes into a sample. Horseshoe crabs are an extremely ancient group and are often referred to as living fossils.Their fossil relatives are recognized as far back as the Ordovician Period (485.4 million to 443.8 million years ago), and forms similar to modern-day horseshoe crabs date back to the Jurassic Period (201.3 million to 145 million years ago). horseshoe crabs are incredibly old. Facts About Horseshoe Crabs and FAQ The American horseshoe crab is a common sight on Florida's beaches. By virtue of their relatively simple wiring, they’re easy to study and have taught us a great deal about how our own eyes function. Among its uses are assuming rudder duties and helping the arthropod right itself after getting stuck on its back. Before they get a chance to hatch, fish, sea turtles, and birds gorge themselves on the eggs. Even so, it’s estimated that only about 10 of those individual embryos will ever become adults. For instance, some prehistoric species had limbs that split out into two branches, but today's specimens have only one. Shorelines are downright squalid: a single gram of undersea sediment contains roughly 1 billion bacteria. They’ve transformed quite a bit over the past half-billion years. With so many animals utterly dependent on this fodder, nesting horseshoe crabs are vital to the ecology of Delaware Bay and countless other regions around the world. Unlike real crabs and their kin, horseshoe “crabs” lack antennae. Without these magnificent animals, thousands—perhaps even millions—of people might have died during the past four decades from unsanitary injections. Copper turns bluish-green when it oxidizes. Both larvae and fully grown horseshoes eat aquatic worms. The plodding sea creatures have weird blood, weirder swimming habits, and a secret weapon that’s probably saved your life. Discovered in 2008, the 25 millimeter-wide Lunataspis aurora crawled over Manitoba 445 million years ago. Though adults will also devour algae and carrion, they predominantly consume clams and mussels. During the night, a female will climb ashore with a male (or several) in hot pursuit. Migratory shore birds descend upon the bay in huge numbers, fattening themselves on the nutrient-rich eggs. Towards the front of the shell are two tiny median eyes and a single endoparietal eye. This makes it the world’s oldest-known horseshoe crab. Natural history. Stinging isn't one of them, despite what many falsely believe. In the 1970s, the FDA made this test mandatory for experimental drugs and surgical implants. Among these avians are scores of red knots, which use the crab fest as a final pit stop during their yearly migration from the Arctic to South America. Unlike us, the arthropods lack infection-fighting white blood cells. When it comes to reproduction, females also mature more slowly: While males are ready to mate by age 8 or 9, their counterparts don’t start breeding until age 10 or 11. Whereas our blood uses iron-based hemoglobin to transport oxygen throughout the body, horseshoe crabs rely on hemocyanin, which contains copper. Horseshoe crabs are much more closely related to arachnids like spiders and ticks than true crabs. Four species are with us today, all of which closely resemble their long-extinct ancestors. Supposedly frozen in time, horseshoe crabs are often hailed as “living fossils” by the media. Four species are with us today, all of which closely resemble their long-extinct ancestors. Researchers have been trying to develop synthetic amebocytes. Yet, appearances can be misleading. A mother can lay as many as 90,000 eggs per clutch. Walking around on the ocean floor is generally how horseshoe crabs get from point A to point B. They’re part of the Subphylum Chelicerata and are further classified into Class Merostomata, which includes horseshoe crab species as well as eurypterids (sea scorpions). Behind each one, there’s a small, primitive photoreceptor called a lateral eye. Come mating season, these bean-shaped units help amorous crabs locate a partner. Ever since Johns Hopkins University physician Frederick Bang discovered this characteristic in 1956, medical scientists have been capitalizing on it. -known horseshoe crab. If the cells start releasing their goo, it’s because they’ve encountered bacteria and, therefore, the product isn’t ready yet. Instead, special cells called amebocytes attack pathogens in the horseshoe crab's body by sealing them inside a gooey physical barrier, thus halting the malady’s spread. Discovered in 2008 , the 25 millimeter-wide Lunataspis aurora crawled over Manitoba 445 million years ago. Horseshoe crabs are “living fossils” meaning they have existed nearly unchanged for at least 445 million years, well before even dinosaurs existed. Members possess two main body segments and a pair of unique, pincer-like feeding appendages called chelicerae (hence the name).