How many hearts does a shark have?

A shark has one heart, which is a two-chambered heart.
1. Structure of the Shark’s Heart:
o The heart of a shark is composed of two chambers:
 One atrium (auricle): This chamber receives deoxygenated blood from the body.
 One ventricle: This chamber pumps the blood to the gills for oxygenation.
2. Circulatory System in Sharks:
o Sharks have a single circulation system. This means that blood passes through the heart only once during each complete circuit of the body.
o The heart pumps deoxygenated blood to the gills, where it gets oxygenated. The oxygenated blood is then distributed to the rest of the body directly from the gills, without returning to the heart.
3. Comparison to Mammals and Other Animals:
o Unlike mammals (which have a four-chambered heart) and some amphibians or reptiles (which may have three chambers), sharks have a simpler heart structure suited to their aquatic environment and metabolic needs.
A shark has one two-chambered heart that effectively supports its circulatory system, ensuring oxygen delivery throughout its body.