regurgitated blood

Richard DawkinsのThe God Delusionを読んでいます。
In humans, IOUs and money are devices that permit delays in the transactions. The parties to the trade don't hand over the goods simultaneously but can hold a debt over to the future, or even trade the debt on to others. As far as I know, no non-human animals in the wild have any direct equivalent of money. But memory of individual identity plays the same role more informally.
Vampire bats learn which other individuals of their social group can be relied upon to pay their debts (in regurgitated blood) and which individuals cheat. Natural selection favours genes that predispose individuals, in relationships of asymmetric need and opportunity, to give when they can, and to solicit giving when they can't.
吸血コウモリが本当に存在するとは知りませんでした。すると "regurgitated blood" の "regurgitate" は血を吸う事と関係があるようですが、辞書で意味を調べます。
・Oxford English Dictionary: Bring (swallowed food) up again to the mouth.: gulls regurgitate food for the chicks
・Collins Dictionary: If a person or animal regurgitates food, they bring it back up from their stomach before it has been digested.:[formal] Sometimes he regurgitates the food we give him because he cannot swallow.
"regurgitate" は吸うのではなく戻すのですね。 Vampire batsは二日間血を吸えないと死んでしまうので、その様な場合には仲間に血をねだり、血を分け与えてもらう習性があるとWikipediaに説明がありました。一旦食べた物を戻すとなると、牛などの反芻動物の "ruminate" を直ぐに連想しますが、意味に違いがあるのでしょうか？　 "ruminate" の意味も辞書で確認します。
Collins Dictionary: When animals ruminate, they bring food back from their stomach into their mouth and chew it again.
"regurgitate" は単に戻すだけの意味の様ですが、"ruminate" は反芻するために戻すのですね。また "ruminate" には次の意味もあり、
If you ruminate on something, you think about it very carefully.
面白いことに "regurgitate" には次の意味があります。
regurgitate: If you say that someone is regurgitating ideas or facts, you mean that they are repeating them without understanding them properly.