Horseshoe crabs are living fossils. They have changed very little since their first existence on Earth more than 400 million years ago. However, they are not true crabs. They are more closely related to spiders and ticks. Their closest relative is the sea spider, which is not really a spider.
Horseshoe crabs rely on healthy beaches and estuaries to reproduce, and changes in their population can signal environmental problems.
They are also important to humans. Their blood contains a special enzyme called limulus amebocyte lysate, or LAL. LAL is used to test medicines, vaccines, implants, and other medical devices for bacterial endotoxins, ensuring medical equipment is safe for people.
For information about Dauphin Island Sea Lab programs and the Aquarium, visit disl.edu/
This Learning Minute segment is brought to you by Dauphin Island Sea Lab, Alabama’s Marine Education and Research Center, and The Alabama Aquarium.