Spiracle (arthropods)
A spiracle or stigma is the opening in the
Most myriapods have paired lateral spiracles similar to those of insects. Scutigeromorph centipedes are an exception, having unpaired, non-closable spiracles at the posterior edges of tergites.[2]
Velvet worms have tiny spiracles scattered over the surface of the body and linked to unbranched tracheae. There can be as many as 75 spiracles on a body segment. They are most abundant on the dorsal surface. They cannot be closed, which means velvet worms easily lose water and thus are restricted to living in humid habitats.[3]
Although all insects have spiracles, only some arachnids have them. Some spiders such as orb weavers and wolf spiders have spiracles. Ancestrally, spiders have book lungs, not trachea. However, some spiders evolved a tracheal system independently of the tracheal system in insects, which includes independent evolution of the spiracles as well. These spiders retained their book lungs, however, so they have both.[6][7] Harvestmen, camel spiders, ricinuleids, mites, and pseudoscorpions all breathe through a tracheal system and lack book lungs.
Literature
- Chapman, R.F. (1998): The Insects, Cambridge University Press
References
- ^ Solomon, Eldra, Linda Berg, Diana Martin (2002): Biology. Brooks/Cole
- ^ S2CID 227191511.
- ^ a b "Untitled 1". lanwebs.lander.edu. Retrieved 2023-02-06.
- ISBN 0-412-61390-5.
- ISBN 9781405107242.)
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: CS1 maint: multiple names: authors list (link - ^ "How Do Spiders Breathe?". Sciencing. Retrieved 2021-06-06.
- S2CID 16863495.