Physiology of Finfish and Shellfish (2+1)

2.2.3. Peristaltic pumps or Chamber pumps

Peristaltic pumps or Chamber pumps have contractive walls or the reduction in volume is achieved by external pressure from other body parts. Peristaltic hearts are found mostly in invertebrates.

Vertibrate blood is carried in a system of elastic tubes or pipes (arteries, capillaries, veins). Blood returns to the heart without leaving this system of tubes and because the blood remains within this closed system, we refer to vertebrate circulation as closed circulation. In many invertebrates (e.g. insects, most crustaceans, many molluscs) blood is pumped from the heart into the blood vessels, but there terminate and blood flows more or less truly between the tissues before it eventually returns to the heart, such a system is called are open circulation.