Vertebrates are animals with a backbone. They have a closed circulatory system that transports blood throughout the body. Two types of circulation are found in vertebrates, single circulation, and double circulation.


Single circulation is found in fish and some amphibians. In single circulation, the heart has only one atrium and one ventricle. The atrium receives deoxygenated blood from the body, and the ventricle pumps it to the gills where it picks up oxygen. The oxygenated blood then passes to the rest of the body before returning to the heart. Single circulation is less efficient than double circulation as the blood pressure is lower.


Double circulation is found in reptiles, birds, and mammals. In double circulation, the heart has two atria and two ventricles. One side of the heart pumps deoxygenated blood to the lungs, where it picks up oxygen. The oxygenated blood then travels to the other side of the heart, which pumps it to the rest of the body. Double circulation is more efficient as it maintains a higher blood pressure, ensuring that oxygen is delivered to the tissues more efficiently.


Double circulation has several advantages over single circulation, including:

• Efficient delivery of oxygen to the tissues


• Higher blood pressure


• Allows for the separation of oxygenated and deoxygenated blood


• Enables the body to maintain a higher metabolic rate

In conclusion, single circulation is found in fish and some amphibians, while double circulation is found in reptiles, birds, and mammals. Double circulation is more efficient than single circulation, allowing for the delivery of oxygen to the tissues more effectively, maintaining a higher blood pressure, and enabling the body to maintain a higher metabolic rate.

The main difference between single circulatory systems and double circulatory systems is that in the case of single circulatory systems, blood passes through the heart only once on each circuit around the whole of theblood circulation system of theanimal.