Spiders- A Layman’s View
Some time ago, I heard a lecture by one of my Zoology Professors about spiders. He was explaining the part their tactile sense played in helping spider’s to catch their prey. He said that even though their power of vision is weak, spiders are able to descend swiftly & accurately to the prey ensnared in their webs. This amazing fact was not clearly explained until W Mitchell Masters & Hubert Market proved that this was done with the help of the spiders highly developed tactile sense. A prey on falling on the web sends out vibrations. These vibrations do not fan out equally on all sides but in clearly defined directions. Due to this a spider is able to locate the exact location where its prey is ensnared. It is now apparent that the webs strands are excellent conductors of rapid oscillations. The spider’s tactile sense is in turn highly sensitive to these vibrations. After hearing this lecture, I carried out a simple experiment. I dropped a small leaf on to a web. The spider sitting in the middle of the web rapidly & accurately descended on it. But on sensing that it was not food, it went back to its original position. I then dropped another leaf on a different part of the same web. But this time the spider did not even care to move. Even though I tried dropping leaves several times, the spider did not seem to move at all. My zoology professor did not find a satisfactory explanation for the spider’s behavior. It may be true that spiders reach their prey by sensing the oscillations of their webs. But how do they differentiate the prey from other materials?
Article By: Stephen Francis, St.Albert's College
Some time ago, I heard a lecture by one of my Zoology Professors about spiders. He was explaining the part their tactile sense played in helping spider’s to catch their prey. He said that even though their power of vision is weak, spiders are able to descend swiftly & accurately to the prey ensnared in their webs. This amazing fact was not clearly explained until W Mitchell Masters & Hubert Market proved that this was done with the help of the spiders highly developed tactile sense. A prey on falling on the web sends out vibrations. These vibrations do not fan out equally on all sides but in clearly defined directions. Due to this a spider is able to locate the exact location where its prey is ensnared. It is now apparent that the webs strands are excellent conductors of rapid oscillations. The spider’s tactile sense is in turn highly sensitive to these vibrations. After hearing this lecture, I carried out a simple experiment. I dropped a small leaf on to a web. The spider sitting in the middle of the web rapidly & accurately descended on it. But on sensing that it was not food, it went back to its original position. I then dropped another leaf on a different part of the same web. But this time the spider did not even care to move. Even though I tried dropping leaves several times, the spider did not seem to move at all. My zoology professor did not find a satisfactory explanation for the spider’s behavior. It may be true that spiders reach their prey by sensing the oscillations of their webs. But how do they differentiate the prey from other materials?
Article By: Stephen Francis, St.Albert's College
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