capable of slightly more rapid twitches. Very rapid movements of insects, such as wing beat frequencies of 200 to 300 per second, are made possible by vibratory action of elastic portions of the cuticle, the muscles themselves contracting no more rapidly per stimulus than those of a bird. The tremendous power per body weight and size of many insects (such as the giant horned scarabs, Dynastes) is also an illusion. Strength results from the exertion of short fibers arranged along the entire length of leg joint surfaces so that the load is evenly and widely distributed. Power output and metabolic rates of insects, however, are much higher than in vertebrates, the result of a direct and continuous oxygen supply via the tracheal system.

Gross anatomy of the musculature is highly complex, and there may be hundreds of discrete muscles in even a small insect. An early anatomist described over 4,000 in the goat moth caterpillar, as compared to a mere 529 in humans. This richness of muscles combined with mechanically diverse articulations permits a diverse repertoire of intricate movements by these animals.

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