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Physostomes (from Greek physa 'bladder' and stoma 'mouth') is the name of a group of bony fish .

In these, the swim bladder is connected to the intestine, i.e. the embryonic connection between the intestine and the swim bladder ( ductus pneumaticus ) is still present in the fully grown (adult) state (in contrast to the physocists ). It can be opened and closed by muscles, thereby regulating the degree of filling. The swim bladder is filled by swallowing air; in addition, gas is secreted via a gas gland or absorbed via capillaries, as is the case with the physocists. The physostomes include, for example, the pike , salmon fish , coregons and carp species . They are predominantly freshwater species.

In various physostomes, for example tarpon ( megalops ), butterfly fish ( pantodon ), African bonesfish ( heterotis ), dogfish ( umber ), the swim bladder can contain respiratory epithelium and can be used not only hydrostatically as a swimming organ, but also for gas exchange. It is then also referred to as the lung.

See also

  • Noble fish (Physostomi) - obsolete taxon (Müller, 1844)


  • Wilfried Westheide, Gerhard Rieger (editor): Special zoology. Part 2: vertebrates or skulls. 2nd edition, 2010. Spectrum Academic Publishing House (Springer), Heidelberg. ISBN 978-3-8274-2039-8 , on page 279.
  • Milton Hildebrand, Georg E. Goslow: Comparative and functional anatomy of the vertebrates. Translated from the American by Claudia Distler. Springer Verlag, Berlin and Heidelberg 2004. ISBN 978-3-642-62375-2 , on page 257.

Individual evidence

  1. Physostomes. In spectrum Academic publisher: Lexicon of Biology (1999, online on