Horseshoe crabs are one of Earth’s oldest creatures and are often referred to as “living fossils,” predating the dinosaurs by more than 200 million years. They have a hard shell or exoskeleton for protection and a long tail that acts as a rudder to help them move through the water or flip themselves when overturned on the shore. Horseshoe crabs have a unique, copper-based blue blood that contains a substance called "Limulus Amebocyte Lysate," or "LAL."

Fun Fact: Horseshoe crabs aren’t actually crabs and are more closely related to spiders or scorpions.

According to the National Oceanic and Atmospheric Administration (NOAA), the Delaware Bay has the largest population of horseshoe crabs in the world, and scientists from NOAA’s National Estuarine Research Reserves System help conduct annual horseshoe crab spawning surveys, which is a Delaware Bay-wide effort. Adventure Aquarium participates in these surveys every season, helping to continue local conservation efforts.