Fish- The purpose of the cardiovascular system is to distribute the blood throughout the body. By doing so it removes metabolic waste and carbon dioxide from the tissues while simultaneously supplying the necessary nutrients and oxygen. To power this important and crutial system there must be a main power source. The heart is the main power supplier of the circulatory system which drives its functionality. Beyond the heart the circulatory system is comprised of the three major types of blood vessels: arteries, veins, and capillaries.
To say there are only two types of circulatory systems, open and closed, is a simplification of an in depth and comprehensive subject. The differences in cardiovascular systems from specie to specie is far
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Finding an array of systems with varying differences. They discovered that certain species hearts emplement placating blood vessels where others use the heart to drive the blood. Somewhere between six hundred and seven hundred million years ago lived the last common ancestor between protostomes and deuterosomes. Unfortunately because of limited and rare fossils the exact anatomy and specification are questionable. Some scientists believe that this was the time of major evolution. The reason was to push the blood to through the bulkheads of segmented species. It is speculated that the blood was pumped by peristaltic vessels, similar to those in moluscs. What makes the system different or deemed closed was the blood that would permeate through the spaces in the extracellular matrix. Throughout the rest of history the circulatory system has continued to go through considerable and momentous reformations. All vertebrates now possess an endothelium. During the divergence of urochordates and cephalochordates, was when researchers first found the endothelium to appear, which leads some scientists to believe cardiovascular evolution really began somewhere closer to five hundred million years ago.
Next scientists pondered why the endothelium was advantageous or beneficial to early vertebrates. Many have hypothesized