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First published online February 4, 2005
Journal of Experimental Biology 208, 661-670 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01427
The early life history of tissue oxygenation in crustaceans: the strategy of the myodocopid ostracod Cylindroleberis mariae
Laboratoire d'Ecophysiologie et Ecotoxicologie des Systèmes Aquatiques, UMR 5805 Université Bordeaux 1, France and CNRS, Place du Dr B. Peyneau, 33120 Arcachon, France
* Author for correspondence (e-mail: jc.massabuau{at}epoc.u-bordeaux1.fr)
Accepted 1 December 2004
We studied basic principles of respiratory physiology in Cylindroleberididae, Cylindroleberis mariae Baird 1850, which are millimetre-sized crustaceans (myodocop ostracod) having a fossil record dating back to about 425 millions years ago. Facing experimental changes of O2 partial pressures in the range 2-40 kPa (normoxia is 21 kPa), C. mariae lack any regulatory mechanism to adapt their ventilatory and circulatory activity. Thus, the oxygenation status of their internal milieu must follow, as a dependant variable, the ambient oxygenation. Freely behaving C. mariae exhibit a marked diurnal activity rhythm. They are actively swimming in the water column during night, where they inspire in normoxic-normocapnic water. They are resting in self-made nests during daytime, where they are rebreathing in a confined and hypoxic environment. By analogy to extensive previous literature data, we suggest that these changes of respiratory gas content, and the associated tissue gas status, participate to the shaping of their metabolic activity and behaviour. To conclude, as Cylindroleberididae are early crustaceans exhibiting a remarkable stasis since the Palaeozoic, present data illustrates how principles of tissue oxygenation strategy can cover an impressive time scale.
Key words: respiration, evolution, crustacea, control of breathing, oxygen regulation, hypoxia, hyperoxia, circadian rhythm
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