What is the purpose of a circulatorycardiovascular system in

What is the purpose of a circulatory/cardiovascular system in an animal? What animals have them? How are they different in animals that do have them?

Solution

During the process of evolution the complexity of the organism increase continuously to facilitate different functions. One of them is cardio vascular system, which helps to circulation of the blood to different organs and brought the deoxygenated blood to heart for purification and purified blood pumped to different organs. This also maintains the blood volume, any abnormality leads to increased or decreased blood volume leads to death of the animal. Fishes, amphibians, reptiles, aves and mammales have the heart. In fishes the circulation is single systemic circulation through the grills. In amphibians, reptiles aves and mammales two types of circulation in one is pulmonary and other is systemic circulation, pulmonary circulation from Lungs to heart and systemic circulation from heart to different organs.