Horseshoe crabs (Limulus polyphemus)
The heart of the Horseshoe crab (Limulus polyphemus) extends almost over the entire length of the crab. The heart of the crab beats at about 32 beats per minute. The horseshoe crab has an open circulatory system. This system serves many purposes. The heart has eight pairs of openings or ostia, which blood (hemolymph) pours in and out of. Blood is transported through the crab's body through arteries. As the blood is flowing, it is collecting oxygen for the crab's gills. The crab also uses this system to excrete waste products. The horseshoe crab evolved during the Cambrian period.
An interesting fact about the blood of this horseshoe crab is that it contains the protein Limulus amebocyte lystate (LAL). This protein detects any bacterial toxins. Scientists can actually use this protein to ensure that vaccines and medications are not contaminated with bacteria!
An interesting fact about the blood of this horseshoe crab is that it contains the protein Limulus amebocyte lystate (LAL). This protein detects any bacterial toxins. Scientists can actually use this protein to ensure that vaccines and medications are not contaminated with bacteria!