Fish survives by hiding in trees

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Biologists studying a killifish found in estuaries on the western Atlantic have found that the fish can spend months living within hollow logs when their pools partially dry up.

The Mangrove killifish, Kryptolebias marmoratus, lives in brackish water mangrove areas and can become stranded in tiny pools of water when the water recedes.

According to the results of a study, which is due to be published in a forthcoming issue of The American Naturalist, the species survives life in the near dried-up pools by wriggling inside rotting logs in the water, says New Scientist.

The authors of the paper found hundreds of Mangrove killifish living inside tracks in hollow logs that had been carved out by insects. The fish were lined up nose-to-tail "like peas in a pod", says the report.

The species has adapted for life in these conditions and has special gills that can be remodelled to allow them to excrete wastes effectively in air as well as underwater.

Selfing hermaphroditeThe study demonstrating hermaphoroditism in Kryptolebias marmoratus was published in the journal Molecular Ecology earlier this year.

The species has also been shown to be a hermaphrodite and is believed to be the only vertebrates that is self-fertilising.

"The rotting logs may help explain how the killifish occupy such a large range, stretching from southern Brazil to central Florida.

"Self-fertilisation makes it easy for individuals to colonise new places, and dead logs are good rafts for getting around," evolutionary biologist John Avise, told New Scientist.

For more information see the following papers: Tatarenkov A, Gao H, Mackiewicz M, Taylor DS, Turner BJ, Avise JC (2007) - Strong population structure despite evidence of recent migration in a selfing hermaphroditic vertebrate, the mangrove killifish (Kryptolebias marmoratus). Mol Ecol. 2007 Jul ; 16(13): 2701-11 .

Nilsson GE (2007) - Gill remodeling in fish--a new fashion or an ancient secret? J Exp Biol. 2007 Jul ; 210(Pt 14): 2403-9.