S. Schaefer

Climbing Catfish Discovered in Venezuela

January 24, 2009 07:59 AM
by Lindsey Chapman
In a surprising evolutionary development for fish, a catfish with the ability to climb has been discovered in Venezuela.

Fish Evolution

Venezuela’s climbing catfish was actually found nearly two decades ago, but because a sample collected for study was in poor condition, scientists weren’t able to learn more.

Now they have finally found the river that is home to the fish, a tributary of the Orinoco River, “and literally picked 84 specimens off of rocks,” National Geographic reported.

The previously unknown species, named Lithogenes wahari, has “two leg-like” pelvic fins that are flexible and help it move along rocks, and a strong mouth that it uses as a tool for grasping. These qualities are highly useful for the region, as the fish live in streams with strong flowing waters.

The new catfish has characteristics of two families of fish: armored catfishes and climbing catfishes. In addition to its grasping pelvic fins, the fish also has a bony armor that protects its head and tail.

“The combination of features suggests that common ancestors to both fish families lived in upland streams of the Amazon and Orinoco Rivers, which currently house most of the groups' members,” National Geographic explained.

“We see new fish species all the time, but when you also get new information about the biological history of a group, it's the most fun,” ichthyologist Scott Schaefer said in a LiveScience article.

Related Topic: Other fish discoveries

Walking fish

One fishing trip turned into an international event for a man who made a strange catch at a Crofton, Md. pond in 2002. He took some pictures of his puzzling fish before throwing it back, and later showed the photos to state fisheries biologists. According to “Smithsonian Zoogoer,” the biologists weren’t sure what they were looking at either, but ultimately identified the fish as a northern snakehead. The fish “didn’t belong in the wild in Crofton, or anywhere in the United States for that matter,” the publication reported. It was a non-native species from Asia. Not only is the northern snakehead highly predatory, it also has the ability to walk over land from one body of water to another.

Land-dwelling fish

In 2007, scientists studying a Western Atlantic fish in Belize and Florida observed a new behavior called “logpacking.” They discovered that the mangrove rivulus had the ability to survive dry weather by living out of water for up to 66 days. The rivulus inhabit swampy areas but when water dries up, they have been known to move under logs, in piles of wet leaves and even into discarded beer cans.

“One of us kicked at a log, which broke apart and out came the fish!” team leader Scott Taylor exclaimed.

Different fish, all the same

Researchers examining three fish who all seemed different based on appearance have learned that they’re really one species of fish that goes through incredible changes as it matures. Cetomimidae is a type of whalefish that lives in the deep sea. Scientists have known they existed since the 19th century. However, only females of the species had been found.

Meanwhile, scientists knew that two other species of fish, tapetails and bignose fish, were related to Cetomimidae based on skeletal similarities. Using DNA testing and anatomical studies, they learned that tapetails are Cetomimidae in the larvae stage, and that male tapetails who reach adulthood are bignose fish. Male tapetails gorge themselves with food and as adults, their jaws fuse together and they don’t eat at all. They also develop a large nose to detect smells in the deep water, giving the bignose fish a distinct look from the Cetomimidae.

G. David Johnson, an ichthyologist at the Smithsonian Institution’s National Museum of Natural History, told the Associated Press that the discovery of these fish “tells you how little we know about the deep sea.”

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