An external respiratory opening, especially each of a number of pores on the body of an insect, or each of a pair of vestigial gill slits behind the eye of a cartilaginous fish.
- Catsharks have moderately large spiracles, or respiratory openings, and five pairs of gill slits.
- Insects ‘breathe’ through a tracheal system, with external openings called spiracles and increasingly finely branched tubules that carry gases right to the metabolizing tissues.
- Its spiracles located behind the eyes allow the guitarfish to remain under the sand for long periods of time and breathe easily by flushing clean water over the gills.
- Example sentences
- The lantern nerves, which appear to be modified spiracular nerves, do not synapse directly on the photocytes, but rather in the tracheal system, which in insects delivers air directly to the tissues.
- Two of these tissues, which can be readily dissected, are the anterior spiracular glands of third instar larvae and the male ejaculatory bulb.
- In many cases, the transitional bones and the cheek are separated by a deep extension of the old spiracular slit, referred to in tetrapods as the ‘otic notch.’
Late 18th century: from Latin spiraculum, from spirare 'breathe'.
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