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Most species which use blood (that I know of) use a heart or set of hearts to pump their blood around their body. However, in something like our digestive system, a series of muscles are used to force digested food through tubes instead of a central pump.

My question is, would using a similar ringed muscle series instead of hearts for a species work for pumping blood, or would it be too inefficient to consider?

(for clarification, efficiency is in terms of energy required in proportion to blood successfully moved, and how easily the system could be stopped/interrupted)

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    $\begingroup$ Do you mean like each blood vessel working like a linear peristaltic pump? (Full article on peristaltic pumps) $\endgroup$
    – user95279
    Commented Aug 10, 2022 at 19:30
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    $\begingroup$ We humans use peristalsis in (part of) the lympatic system. And anyway, the heart is actually made of "ring-shaped muscles". $\endgroup$
    – AlexP
    Commented Aug 10, 2022 at 19:32
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    $\begingroup$ I'm not clear what the OP wants. I know we need clarity for an answer to work. The basic difference between what the OP suggests about muscle contractions and already existing hearts is - valves (and two such systems back-to-back in the case of the human heart) and centralisation. So, what does the OP mean? What kind of creature are they designing? @Pelinore $\endgroup$
    – Escaped dental patient.
    Commented Aug 10, 2022 at 20:30
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    $\begingroup$ the heart IS a ring of muscle around a blood vessel. $\endgroup$
    – John
    Commented Aug 10, 2022 at 20:44
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    $\begingroup$ @Pelinore Let me make this absolutely crystal clear so there can be no misunderstanding, no mistaken apprehension about what I'm saying: I agree with you. - Basically I just want the OP to clarify what they've got in mind beyond the blood, i.e. context. A prod about valves might have made them think about that and clarify. Not happened yet obviously, but let's hope they come back before the internet gets old and senile. $\endgroup$
    – Escaped dental patient.
    Commented Aug 10, 2022 at 21:54

4 Answers 4

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Earthworms:

I think you are looking for a circulatory system like the humble earthworm. The very unique structure of the earthworm heart means it lacks a singular heart, but instead has a series of aortic arches that squeeze the body and force the blood through a closed circulatory system. The earthworm also controls this set of "hearts" directly via nervous system like we do, rather than by a secondary set of muscular signals.

earthworm

The question is, what kind of organism do you want to run with this setup? There isn't a lot of information to say how the arrangement works in a larger organism. Cockroaches have a slightly analogous system with 12-13 separate hearts (depending on your definitions) to allow much greater redundancy in a fairly sophisticated organism. The loss of function of part of the system still allows circulation to operate. The cockroach model is using an open circulatory system, so it doesn't match quite as well.

cockroach

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This is literally how the circulatory system of insects works: fruit fly video

Now the context is different from vertebrates: insects have an open, non-pressurised circulatory system, and the dorsal vessel (the peristaltic blood pump) is not even a closed tube, but partially open and sort of just helping the haemolymph slosh around more efficiently.

Whether this design would be sufficient in a closed circulatory system is perhaps debatable. But developmentally speaking, it’s pretty trivial: the heart is already basically a tube (well, a pair of tubes) knotted around itself

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Yes, there are organisms where blood is moved by muscular blood vessels that "contract in peristaltic waves" (source). This is the known alternative to the chambered heart and is seen in some annelids.

The largest and most conspicuous vessel in the earthworm traverses the full length of the animal. It collects blood from other vessels and drives it forwards through contractile peristaltic waves that originate at the posterior end of the animal and move forward.

Peristaltic pumps lack coordination between the blood that is entering the contractile region and the blood that is leaving it. Despite some improvements to the peristaltic design, such as the evolution of one-way valves and coordination in contractions, the loss of energy associated with backflow, distension of wall segments ahead of the stream, and pump reversals constrain body size and metabolic activity. This promotes evolution of the true hearts

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Rather than relying only on a single centralized heart pump to push blood around, humans also have skeletal-muscle pumps sometimes called a "second heart" in the muscles of the lower leg and foot.

When running, these muscles periodically squeeze and contract, not only moving the body, but also squeeze reservoir veins deep inside the muscle, periodically pushing blood out of the muscle and allowing it to flow back in. Valves in those veins allow that blood to flow only in the correct direction (against gravity during the run). Even when standing still, those same valves prevent blood from sinking under the influence of gravity, moving the wrong direction and pooling in the feet.

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