Trade-off between digestion and respiration in two airbreathing callichthyid catfishes Holposternum littorale (Hancock) and Corydoras aeneus (Gill)
- 115 Downloads
In callichthyid catfishes, the posterior intestine is modified to function as an air breathing organ by being air-filled, thin-walled and highly vascularized. These modifications make it unsuitable for digestive functions and digesta has to be transported quickly through this region to minimize disruption of vital respiratory functions. However, the weak muscles of the wall of the respiratory intestine make this problematic. It is hypothesized that the unidirectional ventilatory air current within the respiratory intestine is responsible for the quick transport of digesta through the respiratory intestine. To verify this, movement of digesta through the alimentary tract was examined in Hoplosternum littorale and Corydoras aeneus that were either allowed to breathe air or prevented from air breathing. When air breathing was prevented, digesta was not transported to the rectum in H. littorale and there was a 94% reduction in the amount of digesta in the rectum of C. aeneus. This study suggests that the anterior digestive intestine facilitates the passage of air although it is filled with digesta. The anterior digestive intestine packages digesta into a string of slightly compressed boluses, creating an air channel in the digestive intestine thus allowing air to pass unimpeded.
KeywordsHoplosternum littorale Corydoras aeneus Respiration Digestion Air breathing
Unable to display preview. Download preview PDF.
- Jobert M (1877) Recherces pour servir a lȁ9histoire de la respiration chez les poissons. Ann Sci Nat Zool Paleontol 5(6):1–4Google Scholar
- Lupu H (1914) Recherhes histo-physiologiques du lȁ9intestine du Cobitis fossilis. Ann Sci Univ Fassy 8:52–116Google Scholar
- Lupu H (1925) Nouvelles contributions a lȁ9etude du sang de Cobitis fossilis. Ann Sci Univ Fassy 14: 60–114Google Scholar
- McMahon BR, Burggren WW (1987) Respiratory physiology of intestinal airbreathing in the teleost fish. Misgurnus anguillicaudatus. J Exp Biol 133:371–393Google Scholar
- Persaud DI (2000) The functional morphology of the gut of the Callichthyid catfishes Hoplosternum littorale (Hancock, 1828), Callichthys callichthys (Linnaeus, 1758) and Corydoras aeneus (Gill,1858) Ph.D. Thesis. University of the West IndiesGoogle Scholar