What are the similarities and differences in the circulatory system of a pike and a pigeon?

Birds and fish are at different stages of evolution, and therefore almost all of their organ systems are different.

With regard to the circulatory system, when compared, the following differences can be distinguished:

– birds have a four-chambered heart (2 ventricles and 2 atria), while fish are characterized by a two-chambered heart (1 ventricle and 1 atrium);

– the circulatory system of birds is represented by 2 circles of blood circulation, while in fish it is only 1;

– for birds, the distinction between venous and arterial blood is characteristic, in fish it is “mixed”.

As the similarity of their circulatory systems, it is worth mentioning the closedness of the circulatory systems, the presence of a heart and blood vessels and blood.