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7 - Skeletons and Life

from Part II - Life Here, Implications for Elsewhere

Published online by Cambridge University Press:  24 September 2020

Wallace Arthur
Affiliation:
National University of Ireland, Galway
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Summary

Here, I deal with the issue of how organisms support themselves against the downward pull of gravity. First, I look at the microscopic skeletons of cells, which help both to maintain the shape of a static cell and to alter that of a mobile one. Then I consider the higher-level skeletons that are needed by large multicellular creatures, whether animals or plants. In the animal kingdom, I focus on the solutions to this issue that we find in the three largest phyla. Vertebrates and arthropods have solved the problem of support in what might be called opposite ways – skeletons on the inside and outside respectively (endo- and exo-skeletons). Molluscs are harder to generalize about. An external shell is the commonest hard structure, but in some groups the shell is reduced and internal. Shells are different from endo- and exo-skeletons in that they have to be carried, so are a mixed blessing from a gravitational perspective. Outside the three main animal groups, other skeletal solutions are found. These range from the hydrostatic skeleton of worms to the woody skeleton of trees. Wood has allowed the evolution of the tallest organisms on the planet – coastal redwoods.

Type
Chapter
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The Biological Universe
Life in the Milky Way and Beyond
, pp. 101 - 117
Publisher: Cambridge University Press
Print publication year: 2020

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  • Skeletons and Life
  • Wallace Arthur, National University of Ireland, Galway
  • Book: The Biological Universe
  • Online publication: 24 September 2020
  • Chapter DOI: https://doi.org/10.1017/9781108873154.010
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  • Skeletons and Life
  • Wallace Arthur, National University of Ireland, Galway
  • Book: The Biological Universe
  • Online publication: 24 September 2020
  • Chapter DOI: https://doi.org/10.1017/9781108873154.010
Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Skeletons and Life
  • Wallace Arthur, National University of Ireland, Galway
  • Book: The Biological Universe
  • Online publication: 24 September 2020
  • Chapter DOI: https://doi.org/10.1017/9781108873154.010
Available formats
×