Spiracle (arthropods)

Common card · No. 419565

A spiracle or stigma is the opening in the exoskeletons of insects, myriapods, velvet worms and many arachnids to allow air to enter the trachea. Insect respiratory system differs from vertebrates'. The circulatory system plays a relatively minor role in circulating oxygen and removing carbon dioxide; instead, trachea and air sacs in the insect body allow direct gas exchange, and these tracheal tubes eventually connect to the external environment via spiracles. In most species, the spiracles are controlled by motor neurons in the central nervous system. It can be opened and closed in an efficient manner to admit air while minimizing associated physiological costs, such as water loss during respiration. Many sensory stimuli can affect the control of spiracles in insects, e.g. chemosensory (carbon dioxide, oxygen, etc.) or mechanosensory (sound, touch, etc.). It has been shown that during metabolically intensive behaviors, such as flight, insects can dynamically modulate the spiracle opening...

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