This 450 million-year-old wonder has survived mass extinctions and the latest Ice Age. It’s longevity earned it the nickname “living fossil,” and its tail is just that, a tail (not a stinger). Today, enjoy a few facts about a family of arthropods more closely related to spiders and scorpions than they are to crabs: horseshoe crabs (Limulidae).
- One of the coolest things about horseshoe crabs (and there are many!) is their blood, which is colored blue rather than red. That’s because it has a copper base, not iron, according to Jennifer Mattei, co-director of Project Limulus, a program out of Sacred Heart University studying horseshoes.
- Horseshoe blood may even have a direct impact on your health. It’s used to test vaccine purity because it coagulates when encountering bacteria. If you got a flu shot last year, federal regulations required it be tested with horseshoe blood.
- The animals have 10 eyes and are able to detect both visible and ultraviolet light.
- Several other creatures call a horseshoe crab’s shell home, including barnacles, seal lettuce, flat worms, and blue mussels.
- While breeding, horseshoe crabs will migrate to shallow coastal waters (see above). The male will cling to the larger female’s shell and she’ll lay over 60,000 eggs over the course of several days. Males will then fertilize those eggs externally, “possibly through a cloud of sperm.”
(Image Credit: U.S. Fish and Wildlife Service / Source: WNPR: Mating Season in Long Island Sound Is Prime Time for Horseshoe Crab Researchers, Wikimedia Commons, Sacred Heart University, Project Limulus)
Check out this story by @jeffbradynpr‘s for more information and photos of these “living fossils” -Emily






