Question

Name on animals having single circulation of blood and another having double circulation.

Answer 1

Hint: The single circulation is when a blood flows only once through the heart. It leads to the mixing of the oxygenated and the deoxygenated blood. The double circulation is usually known as when the blood flows twice through the heart. It does not allow the intermixing of the blood.

Complete step-by-step answer:
The circulatory patterns are of two types, the open or the closed. In the open circulatory system the blood pumped by the heart travels and transverse through the large vessels into the open spaces or body cavities called as the sinuses. This is the type of system that can be seen in the arthropods and the molluscs.
In the closed circulatory system, the blood pumped by the heart is always circulated through a closed network of the blood vessels. This system or pattern is considered to be more advantageous as the flow of fluid can be more precisely regulated. The closed circulatory system is present in the annelids and chordates. In all vertebrates in those the organisms in which the notochord is replaced by the vertebral column the heart consists of one or two atria and one or two ventricles. The heart of the lower vertebrates possesses an additional chamber, namely, sinus venosus and the conus arteriosus or the truncus arteriosus.
All the vertebrates have a muscular heart. The fishes have a two-chambered heart with an atrium and a ventricle, while the lungfishes have three chambered hearts. The amphibians and the reptiles possess a three-chambered heart with two atria and a single ventricle, whereas the crocodiles, birds and mammals possess a four-chambered heart with two atria and two ventricles.
In fishes, the heart pumps out the deoxygenated blood which undergoes oxygenation in the gills. The oxygenated blood is then passed to the body parts from where the deoxygenated blood the blood that does not contain oxygen is returned to the heart. This is called the single circulation.
In birds and mammals, the left and the right atria receive oxygenated and deoxygenated blood, respectively which is passed onto the ventricles of the same sides. In this system there is no intermixing of the oxygenated and the deoxygenated blood. This means that the ventricles pump blood out without any mixing, i.e., the two separate circulatory pathways are present in these organisms; therefore, these animals have double circulation. Hence, the fishes possess single circulation and the mammals possess double circulation.

Note: In the amphibians and reptiles, the left atrium gets oxygenated blood from the gills/lungs/skin and the right atrium receives the deoxygenated blood from other body parts. However, both oxygenated and deoxygenated blood gets mixed up in the single ventricle. The heart thus pumps out mixed blood. This is called the incomplete double circulation.