The horseshoe crab contains a substance called "hemocyanin", which is responsible for transporting oxygen. Unlike hemoglobin in mammals and birds, hemocyanin appears blue when it carries oxygen, giving horseshoe crab blood its unique blue color. Hemocyanin also has strong antioxidant capacity, which can help horseshoe crabs resist harmful substances in the environment and maintain their life and health.

Because hemocyanin has powerful antioxidant capabilities, scientists are studying how to convert it into Used in the medical field, such as developing new antioxidant drugs, treating cancer, etc. At the same time, horseshoe crab blood is also used as a biological indicator to detect environmental pollution and harmful substances.