Cardiovascular system of the horseshoe crab
Though many consider them crabs, horseshoe crabs belong to a completely different subphylum than normal crustaceans. The horseshoe crab has been around since before dinosaurs and has remained unchanged for millions of years.
Horseshoe crabs have a long, tubular heart that runs the length of their body. Blood enters the heart from the pericardial chamber through the double-valved, slit-like openings called ostia. From there blood is pumped through the heart until it reaches the three pairs of aortae, the pair of cerebral arteries, and the frontal artery.
Horseshoe crabs have a long, tubular heart that runs the length of their body. Blood enters the heart from the pericardial chamber through the double-valved, slit-like openings called ostia. From there blood is pumped through the heart until it reaches the three pairs of aortae, the pair of cerebral arteries, and the frontal artery.
Blood is pumped from the arterial trunks that stem from the aortae throughout the crab's body. Meanwhile, another pair of large, veinous trunks collect blood from throughout the crab's body and direct it towards the gills, where it is reoxygenated and then brought back to pericardial membrane where it can enter the heart.