What are the different circulation found in all vertebrates

The different circulation found in vertebrates are:

- In fishes the heart pumps out deoxygenated blood which is oxygenated by the gills and supplied to the body parts from where deoxygenated blood is returned those the heart and this is also termed as single circulation.

- In amphibians and reptiles, the left atrium receives oxygenated blood from the

gills/lungs/skin and the right atrium gets the deoxygenated blood from other body parts. However, they get mixed up in the single ventricle which pumps out mixed blood and also termed as incomplete double circulation.

- In birds and mammals, oxygenated and deoxygenated blood received by the left and right atria respectively passes on to the ventricles of the same sides. The ventricles pump it out without any mixing up, i.e., two separate circulatory pathways are present in these organisms, termed as double circulation.