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Comment
. 2014 Mar 18;111(11):3907-8.
doi: 10.1073/pnas.1401745111. Epub 2014 Mar 10.

Oxygen and animals in Earth history

Andrew H Knoll  1 , Erik A Sperling
Affiliations
Comment

Oxygen and animals in Earth history

Andrew H Knoll et al. Proc Natl Acad Sci U S A. .
No abstract available

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
(A) The marine demosponge Halichondria panicea investigated by Mills et al. (5); note centimeter scale in the foreground. (B) Transmission electron microscopy through the body of the calcareous sponge Sycon coactum. The ability of sponges to tolerate low oxygen is probably related to their basic body design, with only two cell layers, the external pinacoderm (p) and the internal choanoderm (c), separated by a largely inert mesohyl (m). Both cell layers are in direct contact with seawater (sw), and diffusion distances for oxygen to any cell are short. (Scale bar, 5 μm.) Thus, sponges and other small thin animals may have been able to tolerate low Proterozoic oxygen levels; however, larger, metabolically active animals, particularly carnivores, would have been excluded. Images courtesy of D. B. Mills (A) and S. Leys (B).
See this image and copyright information in PMC

Comment on

  • Oxygen requirements of the earliest animals.
    Mills DB, Ward LM, Jones C, Sweeten B, Forth M, Treusch AH, Canfield DE. Mills DB, et al. Proc Natl Acad Sci U S A. 2014 Mar 18;111(11):4168-72. doi: 10.1073/pnas.1400547111. Epub 2014 Feb 18. Proc Natl Acad Sci U S A. 2014. PMID: 24550467 Free PMC article.

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