The horseshoe crab, known as the “living fossil,” an animal species identified by its scientific name, Limulidae, is widely known for its life-saving blue blood. These horseshoe crabs are unlike any other crab in the world; in fact, they are not even considered related to other crab species. Horseshoecrab.org states that "they are most closely related to spiders, scorpions and trilobites that existed over 500 million years ago due to their appearance and structure" (Horseshoecrab.org, 2014). According to the American Museum of Natural History, “trilobites are a non-existent class of arthropods that appeared in the early Cambrian period and lived and died before the presence of dinosaurs” (American Museum of Natural History, 2014). The horseshoe crab can be found throughout the world in warm, shallow waters off the coasts of Indonesia, Japan, India, the eastern United States, and the Gulf of Mexico. The external formation of this species has changed very little over time and is composed of a hard exoskeleton, ten eyes, ten legs and a long, thin tail that they use to steer when they are moving. These crabs are naturally nocturnal animals that come out in the shadows of the night to forage for food. They are also said to be omnivores and will consume just about anything, but their main prey is worms, molluscs and crustaceans. Their main predators are sharks, turtles, coastal birds and humans. The dimensions of these crabs range from approximately 8 to 24 inches in length and weigh between 2 and 10 pounds. The average lifespan of horseshoe crabs is around 15 to 30 years, but it all depends on the habitat, life cycle, and additional risk factors that the crabs are prone to. They tend to come back to shore when it's time to mate and...... middle of paper...... the aviator of these crabs has changed significantly. They became slower, moved less, had different movement patterns, and became more stressed and confused. Scientists consider the main concern with these changes to be due to the crabs being captured and bled just before their mating cycle. That said, once the crabs change their behavior, they are washed ashore or into the water without any desire to do anything usual, like reproduce, which contributes to the decline of this species. “One solution to the decline of these crabs would be to wait until the end of the breeding season to capture and bleed the crabs” explains Chabot (BBAHCB, 2014). Researchers are looking for methods to better help these crabs live longer and continue to reproduce without any of these effects, hoping that one day this amazing species will truly be able to live freely..