Washington, Nov 7 : Scientists have discovered a completely new trait in a small Western Atlantic fish known as Mangrove rivulus. This fish, also known as the mangrove killifish, is native to the Americas and is about two inches (five centimeters) long.

According to a team of scientists on an excursion trip to Belize and Florida, the fish lives in logs and breathes air for months at a time.  The team has named this particular aspect of the fish as 'logpacking'.

The team found out this unusual behaviour when they were trying to find out how the Mangrove rivulus survived the frequent dry spells that strike its swampy forest habitat. "One of us kicked at a log, which broke apart and out came the fish," said Scott Taylor of Brevard County, Florida's Environmentally Endangered Lands Program.

The team speculates that the logs might serve an additional purpose, that of acting as cheap transport when storms send the wood drifting. But proving this will require additional research.

Scientists had earlier found out that when small pools of water dried up, the rivulus settled into crab burrows, which disappeared during extreme dry spells.

"Sometimes the pools have very heavy rivulus populations, and they have to go somewhere when they dry," said Taylor.

Thought he researchers had seen the fish under logs, damp leaves, inside coconuts and even beer cans, they were extremely surprised to find it jammed together in tree remains, which quickly get hollowed out by termites or burrowing beetles in mangrove forests.

"It now appears that another option for emersion (the behavior of leaving the water) is to enter logs," Taylor said. "We now suspect that logs may be foci for these emersed pool populations," he added.

The fish has long been studied for its many unique features.

For example, it's the only vertebrate known to naturally self-fertilize. In some populations, it can become a hermaphrodite, developing both male and female parts simultaneously, to produce clones of itself.

"The animal can also live out of water for up to 66 days and is one of very few fish species that spend their entire lives in mangrove swamps," said Taylor.

Lab experiments have also helped to explain the strange inner workings of the fish.

According to Patricia Wright, a biologist who has done the experiments, "In addition to its long stints in air, the fish shrugs off large variations in water temperature, pH, salinity, oxygen level, and even the level of pollutants."

"It's an exceptional animal as it is able to survive in air for a long period of time without going into an altered metabolic state such as a lungfish might," said Wright.

Scientists also found surprising changes in how the fish deals with waste. Normally, fish excrete waste products such as nitrogen through their gills, but experiments show that the rivulus uses its skin for this as well. (ANI)