阅读理解
A tropical fish that lives in mangrove swamps(湿地)across the Americas can survive out of water for months at a time, similar to how animals adapted to land millions of years ago, a new study shows.
The Mangrove Rivulus, a type of small tropical killerfish, seeks refuge in shallow pools of water in crab caves, nut shells or even old beer cans in the tropical mangrove swamps of Belize, the United States and Brazil.
When their living place dries up, they group together on the land in hollowed logs(圆木)and breathe air through their skin instead of their gills(腮)until they can find water again.The fish, whose scientific name is Rivulus Marmoratus, can grow as large as three inches.
The scientific breakthrough came after a trip to Belize.
“We kicked over a log and the fish just came dropping out,”Taylor told Reuters in neighboring Guatemala by telephone.He said he will publish his study on the fish in The American Naturalist journal early next year.
In lab tests, Taylor said he found the fish can survive for up to 66 days out of water without eating, and their metabolism(新陈代谢)keeps functioning.
Some other fish can survive briefly out of water.The walking catfish found in Southeast Asia can move about over land for hours at a time, while lungfish found in Australia, Africa and South America can survive out of water, but only in a sleeping state.
No other known fish can be out of water as long as the Mangrove Rivulus and remain active, according to Patricia Wright, a biologist at Canada's University of Guelph.
“These animals live in an environment that is similar to conditions that existed millions of years ago, when animals began making the evolution from water onto land,”she said.
|