I'm currently reading Treatise on Invertebrate Paleontology (A) and don't understand the following fragment:

The affinity for oxygen in lower animals is many times that in higher ones, whereas conditions are the reverse with regard to carbon dioxide.

What does it mean by "affinity"? Affinity of hemoglobins (in blood)? Affinity of oxygen-transporting molecules, whatever they are? Something else? The book doesn't provide a source of its claim here.

EDIT: @Will - I'm more interested in what kind of affinity they are speaking about in regards to carbon dioxide (I can't comment due to not having enough reputation yet.)

  • 1
    $\begingroup$ Can you include more of the surrounding text to help with context? $\endgroup$
    – Alan Boyd
    Aug 8 '17 at 15:59
  • $\begingroup$ @AlanBoyd "Their [i.e. aerobic organisms'] needs vary according to degree of activity and environmental conditions. In any given case, oxygen requirements can be extremely different, and such variations are usually determined by the affinity of special hemoglobins for oxygen. [The quote above is here.] Humans require an oxygen to carbon dioxide ratio of 250 to 1. In contrast, Arenicola marina needs only a ratio of 50 or 70 to 1. Many lower organisms, especially polychaetes, can tolerate considerable decreases in the amount of oxygen that they take in without the slightest organic damage." $\endgroup$
    – mjmjvmm
    Aug 8 '17 at 16:26
  • $\begingroup$ In your comment it says "affinity of special hemoglobins for oxygen". That is not the same block text as your question. I think they are speaking to the ability of worms and the like to scrounge O2 out of environments that would be much too hypoxic for vertebrate life. They can do that because their hemoglobins have greater affinities for O2. You can read up on bloodworms for an excellent example. $\endgroup$
    – Willk
    Aug 9 '17 at 19:32
  • $\begingroup$ In English "A has an affinity for B". We know what B is (oxygen) but you are expecting us to be able to guess what A is. I'm afraid that you are not supplying enough information for anyone to be expected to help you. $\endgroup$
    – David
    Aug 10 '17 at 12:23
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    $\begingroup$ The phrase "lower animals" is so vague as to be completely useless. $\endgroup$
    – kmm
    Aug 10 '17 at 20:23

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