Which animal has a three-chambered heart?

Three-chambered hearts have two large groups of vertebrates – Amphibians and Reptiles, although the latter sometimes violate this rule (crocodiles have a four-chambered heart, which is associated with their secondary aquatic lifestyle – for effective breath holding, it is necessary to saturate the tissues well with pure arterial blood). Animals with a three-chambered heart have devices for limiting the mixing of blood: in amphibians, these are special pockets in the ventricle, where arterial blood flows, and in reptiles, a horizontal septum through which blood is poured and mixed only partially.