All member of class Hexapoda are insects, with three pairs
of legs, three body sections, generally one or two wing pairs,
and one pair of antennae. Insects are the only terrestrial animals
living, besides birds and bats in own phylum Craniata, that
evolved flight capability (Figure H), for which the earliest evidence
comes from winged insects preserved as fossils. Flight by
insects is possible because the combination of small body size
and highly specialized striated muscles for rapid, strong contraction
enabled the predator avoidance afforded by flight (insect
flight evolved before the evolution of insect-hunting bats and
humans wielding butterfly nets). Water loss increases during
flight because of increased movement of air past the insect body;
dehydration is slowed by the waxy cuticle, by closeable spiracles,
and by excretion of solid waste as almost dry uric acid by the
Malpighian tubules—the excretory organs located in the insect
hemocoel. The vast array of muscle and exoskeletal designs in
many species of flying insects coupled with a well-developed
respiratory system and adequate storage of energy supply meet
flight requirements of as many as 1000 wing beats per second.
Finally, well-tuned visual and nervous controls for flight navigation
make insect migration, mating on the wing, hovering, and
food getting possible.
All member of class Hexapoda are insects, with three pairsof legs, three body sections, generally one or two wing pairs,and one pair of antennae. Insects are the only terrestrial animalsliving, besides birds and bats in own phylum Craniata, thatevolved flight capability (Figure H), for which the earliest evidencecomes from winged insects preserved as fossils. Flight byinsects is possible because the combination of small body sizeand highly specialized striated muscles for rapid, strong contractionenabled the predator avoidance afforded by flight (insectflight evolved before the evolution of insect-hunting bats andhumans wielding butterfly nets). Water loss increases duringflight because of increased movement of air past the insect body;dehydration is slowed by the waxy cuticle, by closeable spiracles,and by excretion of solid waste as almost dry uric acid by theMalpighian tubules—the excretory organs located in the insecthemocoel. The vast array of muscle and exoskeletal designs inmany species of flying insects coupled with a well-developedrespiratory system and adequate storage of energy supply meetflight requirements of as many as 1000 wing beats per second.Finally, well-tuned visual and nervous controls for flight navigationmake insect migration, mating on the wing, hovering, andfood getting possible.
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