How Does Life Adapt to a Gravitational Environment? The Outline of the Terrestrial Gastropod Shell
| Autor: | Ryoko Okajima, Satoshi Chiba |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Physics
Ecology Gastropoda Nuclear Theory Shell (structure) Spire (mollusc) Geometry Astrophysics::Cosmology and Extragalactic Astrophysics Conical surface Environment Adaptation Physiological Biological Evolution Models Biological Gastropod shell Gravitation Animal Shells Physics::Atomic and Molecular Clusters Animals Shell balance Locomotion Astrophysics::Galaxy Astrophysics Ecology Evolution Behavior and Systematics |
| Zdroj: | The American Naturalist. 178:801-809 |
| ISSN: | 1537-5323 0003-0147 |
| DOI: | 10.1086/662674 |
| Popis: | How do several characteristics adapt to gravity while mutually influencing each other? Our study addresses this issue by focusing on the terrestrial gastropod shell. The geometric relationship between the spire index (shell height/diameter) and outline (cylindricality) is theoretically estimated. When the shell grows isometrically, a high-spired shell becomes conical in shape and a low-spired shell becomes cylindrical in shape. A physical model shows that the lowest- and highest-spired shells are the most balanced. In addition, a cone shape is the most balanced for a low-spired shell, and a column shape is the most balanced for a high-spired shell. Spire index and cylindricality measured for freshwater gastropods follow the relationship estimated by the model, whereas those for terrestrial gastropods deviate from this relationship. This translates to a high shell being more cylindrical than a flat shell, except in the case of extremely high or low shells. This suggests that the shape of the most balanced shells (lowest and highest shell heights) is constrained by coiling geometry but that relatively unbalanced shells (intermediate shell heights) do not follow a coiling geometry, as a result of adaptation to enable the snail to carry its shell more effectively. |
| Databáze: | OpenAIRE |
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