#18: Spiracles and Tracheae

Litinsects #18: Spiracles and Tracheae

Take a breath in... and out. Have you ever wondered how insects breathe? They don’t have lungs like we do. In fact they use a completely different respiratory system than vertebrates.

Insects breathe through SPIRACLES, which are small holes in the exoskeleton along the thorax and abdomen. A tiny “door” to the spiracle can be opened and closed to reduce water loss

Connected to the spiracles is a network of TRACHEAL TUBES that extend throughout the body. Gas exchange occurs by DIFFUSION across the walls of the smallest tubes.

In insects, the respiratory system is SEPARATE from the cardiovascular system. Their “blood” does not carry oxygen to cells (technically they don’t have blood but a future post will go into that more)

Some insects have collapsible internal sacs to store air for when their spiracles are closed. Aquatic insects use these air reserves while under water and can regulate buoyancy with the air sacs

The coolest thing is, although tracheae extend internally, they are actually invaginations of the exoskeleton so they are still covered by hardened cuticle. When the individual molts, these tubes are also shed. This photo shows these long thin tracheal tubes still connected to a shed exoskeleton (EXUVIA) of an assassin bug.

Photo: © Brandon Thorpe

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