Wednesday, January 20, 2010

Stingrays Determined to be Tool Users

Photo courtesy: ellenm1/Flickr

Once again, we have underestimated the intelligence of another species. Just recently, I did a blog on octopod intelligence that showed them to be more intelligent than originally thought.

Fish have always been thought of as “simple reflex animals” not capable of creativity or even memory for that matter. As an example, the latest wisdom says goldfish have a memory span of three seconds. I find that hard to believe as I (and millions of fish enthusiasts worldwide) have trained goldfish to respond to a tap on the glass at feeding time. Just before I put the food in, I would tap twice on the glass. I always put the food in the same corner; and, my goldfish soon realized that the tapping meant food. They were fed once a day, with 24 hours not 3 seconds separating feedings. It took less than a week; but, as soon as they heard those taps, they all swarmed to the feeding corner with mouths gaping open. So, it comes as no surprise to me (or a million others) that scientists are now finding out that marine animals are more intelligent and more creative than previously thought.

Researchers are now realizing that the reasoning abilities of the stingray can rival that of birds, reptiles and mammals. Part of the reason these marine animals have been considered cognitively simple is because they have been so difficult to study say scientists.

However, scientists at the Hebrew University of Jerusalem in Israel managed to design some clever, creative tasks that would help to determine the intelligence of stingrays.

Photo courtesy: EarthNews

Stingrays are known to use jets of water to dislodge food from plants; and, scientists wondered about their problem-solving abilities.

In one test, some food is hidden in a small plastic tube with only one opening. The stingray demonstrated some keen problem-solving abilities by lying on top of the tube and directing jets of water into the opening forcing the food out. The video of this and another problem-solving stingray can be watched at EarthNews.

Dr. Michael Kuba, the scientist in charge of the research, explains that the jet of water the stingray is using meets the basic definition of a tool. A study conducted by Dr. Benjamin Beck in 1980 caused researchers to define tool use as “using an agent to achieve a goal”.

Tool use is known to occur among fish. At least one other species, the Archer fish manipulates water into jets in much the same way the stingray does. The Archer fish is an amazing shot considering they are below the water line trying to hit an insect on a leaf above the water surface. The average success rate is an astonishing 86%; while, the best of them achieved a mind-boggling 91%.

Stingrays have long been included in the shark category due to the similar skeleton composition of cartilage instead of bone. It was thought that stingrays were similar sharks and were “reflex machines having very acute senses; but, limited cognitive capacities”.

Dr. Kuba says the research may lead to a better understanding of the "vertebrate thought process" and the evolution of vertebrate cognition. The scientists from Israel, Austria and the USA published their study in the journal Animal Cognition.

Via EarthNews and Treehugger

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