Printed in Great Britain ASPECTS OF THE PHYSIOLOGY OF TERRESTRIAL LIFE IN AMPHIBIOUS FISHES
Bony fishes which could spend periods of time out of water, but which lacked special anatomical modifications for survival out of water, were probably involved in the early stages of the evolution of terrestrial life in the vertebrates. The rhipidistian crossopterygians were apparently the group anc...
Main Authors: | , , , , , |
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Other Authors: | |
Format: | Text |
Language: | English |
Published: |
1968
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Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.517.4244 http://jeb.biologists.org/content/50/1/141.full.pdf |
Summary: | Bony fishes which could spend periods of time out of water, but which lacked special anatomical modifications for survival out of water, were probably involved in the early stages of the evolution of terrestrial life in the vertebrates. The rhipidistian crossopterygians were apparently the group ancestral to all higher vertebrates (Romer, 1966; Schmalhausen, 1968), but they are unavailable for study of possible physio-logical adaptations to life on the land. One way we may obtain some idea of the possible range of physiological adaptations which might have been possessed by these ancestral forms is to make comparative studies of pertinent aspects of the physiology of living amphibious fishes. We define amphibious fishes as those which spend periods of time out of water, on or above the ground surface, as normal parts of their life-histories. The most relevant forms are those lacking specialized accessory respiratory organs. Present-day amphibious fishes are all products of long periods of evolution. It is probably impossible to find any living form which completely lacks any structural modifications for terrestrial life. However, there are many forms, belonging to a wide range of systematic categories, which are only minimally modified when compared with their closest purely aquatic relations. Limited information relating to survival and physiological mechanisms of adaptation to life out of water are available for a few of these: the European eel, Anguilla anguilla (Berg & Steen, 1965, 1966); two species of |
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