# Evolution versus "Intelligent Design"

Fish can hold breath for months

If you thought you were the champion of holding your breath under water as a kid, think again. Crucian carp, a fish closely related to the goldfish, can live months without oxygen, scientists have discovered.


“Anoxia related diseases are the major causes of death in the industrialized world,” said Goran Nilsson, a professor at University of Oslo. “Evolution has solved the problem of anoxic survival millions of years ago, something that medical science has struggled with for decades with limited success.”

While ‘Intelligent Design” failed to resolve onf of the major causes of death, evolution has been far ‘smarter’.

A9.13 The crucian carp – plain looking but truly extraordinary G.E. Nilsson (University of Oslo)

(Carassius carassius), a close relative to the goldfish (Carassius auratus), looks very much like any other temperate freshwater cyprinid. However, it has arguably one of the most extraordinary set of adaptations displayed by any vertebrate. It is exceptionally anoxia tolerant, surviving without any oxygen for days to months depending on temperature, and it is the only vertebrate able to survive anoxia while maintaining physical activity and full cardiac out put. For this animal, metabolic depression or “channel arrest” are not prerequisites for anoxic survival, effectively demolishing attempts to claim that there are general principles for how animals tolerate anoxia. The adaptations it displays to survive anoxia include the exotic ability to produce ethanol through a metabolic pathway that is supported by the largest glycogen store of any vertebrate. Moreover, to avoid being anoxic in the first place, it can remodel its gills to boost oxygen uptake and it is in the possession of hemoglobins with higher oxygen affinity than any other vertebrate hemoglobin. In addition to these extraordinary respiratory adaptations, the crucian carp is the only vertebrate known to be able to change its body morphology to avoid being predated – a mechanism induced by alarm substances sent out by fellow crucian carp when they are in the process of being eaten. So, next time you go out to search for extraordinary life forms, do not go by their looks.

Earlier research was published in Science Maintained Cardiac Pumping in Anoxic Crucian Carp by Jonathan A. W. Stecyk, KÃ¥re-Olav StenslÃ¸kken, Anthony P. Farrell, GÃ¶ran E. Nilsson, Science October 2004: Vol. 306. no. 5693, p. 77

and in Hypoxia induces adaptive and reversible gross morphological changes in crucian carp gills JÃ¸rund Sollid, Paula De Angelis, Kristian Gundersen and GÃ¶ran E. Nilsson, The Journal of Experimental Biology 206, 3667-3673 (2003)

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