Chapter 10 - Locomotor Systems

Abstract

The efficient movement of insects on land, in the air, and in water is a major factor in their domination of terrestrial ecosystems. In addition to their maneuverability, insects can lift many times their own weight and jump many times their body lengths. The small size of insects and their apparent strength might at first suggest that their muscles are somehow different from those of vertebrates. However, there is a surprising similarity between the muscles of the two groups; the organization and the basic structure of the muscle fibers in insects are not appreciably different from that of vertebrates, except that in insects the muscles and muscle fibers are smaller and there are fewer muscle fibers in each muscle. Given the functional versatility of insect muscle, there is considerable variation in their structure, oxygen supply, and neural and mechanical coupling. All insect muscles are striated, owing to the regular arrangement of their components; these components produce repeating patterns of light and dark bands under the light microscope, similar to that of vertebrate skeletal muscles. There are two major types of insect muscles: visceral muscles and skeletal muscles. Skeletal muscles are further divided into synchronous and asynchronous muscles, based on their regulation by the nervous system. The contraction of muscles requires energy and an adequate supply of oxygen. The flight muscles of insects have the highest known rates of oxygen consumption for any animal locomotor tissues. This chapter describes the structure of insect muscles and the physiological processes involved in insect locomotion.