In which of the following vertebrate group/groups, heart does not pump oxygenated blood to different parts of the body?
(a) Pisces and amphibians
(b) Amphibians and reptiles
(c) Amphibians only
(d) Pisces only
Fishes have a single closed circulatory system. In this, blood is contained inside blood vessels and circulates in a single direction. Blood flows from the heart around the systemic circulatory route, then returns to the heart again.
Fishes have two-chambered heart that has only one atrium and one ventricle. The atrium gathers blood that has gotten back from the body and the ventricle pumps the blood to the gills where gas exchange takes place and the blood is re-oxygenated; this is called gill circulation or gill flow.
The blood at that point proceeds through the remainder of the body prior to showing up back at the atrium; this is called systemic circulation. This unidirectional progression of blood delivers a slope of oxygenated to deoxygenated blood around the fish's fundamental circuit. The outcome is a breaking point on the measure of oxygen that can arrive at some of the organs and tissues of the body, reducing the overall metabolic capacity of fish.
So the answer is option (d), Pisces only.