I am now studying the structure, innervation and NEC distribution in the respiratory swim bladdet of the Amazon breathing fish Arapaima,Did this fish have more counterpart to some fossil forms(actinistians ) ?
Giacomo
I enclose the TOC list of my special issue on Air Breathing in Fish, I am editing.
None is primitive ! They all share a long evolutionary story, different but not primitive! No group is primitive, some character-states are.
Osteoglossomorphs are among the basal teleostean fishes. For some features, carangoids, for instance, will appear as more primitive than osteoglossids!
Dear Bruno,
So it is more appropriate to use ancient terminology.In fact by studying the molecular, morphological and physiological characteristics of ancient fishes we ought to analyse relevant episodes of our own evolutionary story
Dear Giacomo, I fully agree with Bruno. Osteoglossomorphs are basal teleosts, and their divergence with actinistians dates at least from 430 million years ago. However, it is possible that the common ancestor to all osteichthyans (i.e. actinopterygians and sarcopterygians) already had some ability to breathe air, as also suggested by the lungs of polypteriformes, which are the basalmost actinopterygians. Actinistians (i.e. coelacanths) had large lungs covered with large bony plates since at least 300 Myrs ago, but these became reduced (though still present but rudimentary) when actinistians began to colonize deeper waters about 65 Myrs ago (see Cupello et al. Nature comm. 2017). The rise of air breathing in fishes is indeed a most interesting question in evolution. It not only involves anatomical innovations, but also many physiological ones.
Best wishes
Philippe Janvier
Dear Philippe, Thank you for your discussion. I know Camila Cupello with whom I am collaborating in a paper on the gills of Latimeria.I enclose my last paper in Zoology on the NECs in gill and sckin of P. schlosseri ans a TEM study of Polypterus senegalus and Erpetoichthys lungs.
Best,
Giacomo
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