Living things are grouped taxonomically into vertebrate and invertebrates. Vertebrates are the class of living things that have the backbone which is absent in invertebrates. Examples of vertebrates include fish, amphibians, reptiles, and mammals (Diogo, Kelly, Christiaen, Levine, Ziermann, Molnar & Tzahor, 2015). Vertebrates have various circulatory systems based upon a common plan. The requirements of the vertebrates depending on where they live whether on land or in water contributes to the many circulatory system variations.  This paper explains the various heart chambers found in vertebrates and their examples.

The Variations in Four-chambered Heart in Vertebrates and their Examples

Most of the vertebrates have four chamber heart despites of variations in the circulatory system across the vertebrates. The variations in heart modification are due to the environmental habitation of the vertebrate. For instance, the fish’s heart is two-chambered whereby it entails a single ventricle and an atrium. The two-chambered heart of fish takes after the other vertebrate’s embryo. The heart is further complemented with sinus venosus which assists the circulatory system in passing blood to the atrium with the aid of a thinly walled space in the posterior end of the heart (Diogo, Kelly, Christiaen, Levine, Ziermann, Molnar & Tzahor, 2015).

On the other side, there is a three-chambered heart which is found in frog and other amphibians. Atrium segment is what divides the heart whereby the right atrium is supplied with blood by the systematic circulation. The lungs supply blood to the left atrium. Then, both the oxygenated and deoxygenated blood from the right atrium is allowed to mix in one of the ventricles partially. There exists a spiral valve which aids in the passing of blood from the right side of the ventricle to the pulmonary arteries (Diogo, Kelly, Christiaen, Levine, Ziermann, Molnar & Tzahor, 2015).

There is a three and a half chambered heart in reptiles. The ventricles in the three and a half chambered heart are partially divided. As it is the case in fish, the dorsal aorta helps supply blood from left fourth arch to the fourth right arch.




Diogo, R., Kelly, R. G., Christiaen, L., Levine, M., Ziermann, J. M., Molnar, J. L., … & Tzahor, E. (2015). A new heart for a new head in vertebrate cardiopharyngeal evolution. Nature, 520(7548), 466.