1. Sharks have 3-compartment hearts. Sharks are more closely related to humans in their heart structure than many fishes. The atrioventricular valves have a role similar to the mitral and tricuspid valves in humanos, and the two great vessels carry oxygenated and deoxygenated blood.

2. Sharks have low arterial blood pressures. Sharks have average arterial blood pressures around 45 mm Hg, which is a stark contrast to humans who average closer to 120 mm Hg. This is because sharks lack arterioles, which control the diameter of the blood vessels.

3. Sharks may have regenerative hearts. There is some evidence that sharks are capable of regenerating damaged heart tissue. However, this is still an area of active study, and more research is needed to fully understand the extent of this ability.