These tiny soil-dwellers are the only arthropods that breathe through their heads

Nature · Published 3 October 2026 Swipe more like this →

In short: Known as garden centipedes, symphylans are elusive, eyeless creatures that thrive beneath your feet. While they resemble centipedes, these soft-bodied arthropods are biologically distinct, possessing unique respiratory systems and complex silk-spinning behaviors that have helped them survive since the Cretaceous period. They are far more than mere garden pests.

Symphylans are small, cryptic myriapods, typically measuring between 2 and 10 millimetres in length. Despite their common name, they are not true centipedes. They lack eyes and pigment, dwelling in moist soil environments up to 50 centimetres deep. Their anatomy is highly specialized, featuring a trunk divided into 14 segments. While most adults possess 12 pairs of walking legs, their development is marked by hemianamorphosis, a process where immature individuals hatch with fewer legs and add pairs during successive moults throughout their four-year lifespan.

One of the most striking features of the class Symphyla is their respiratory system. They are the only known arthropods with spiracles located on the head, which connect to a tracheal network branching only through the head and the first three body segments. Their sensory capabilities are equally refined, utilizing long, segmented antennae and Tömösváry organs to detect vibrations in the dark, subterranean spaces they inhabit. Some species, such as the garden symphylan Scutigerella immaculata, are notorious agricultural pests, capable of damaging seeds and roots, though others primarily feed on decaying vegetation.

Their reproductive strategy is remarkably indirect and involves silk. Males deposit hundreds of spermatophores on silk stalks, which females collect with their mouths. The females then store this sperm in specialized pouches and use it to fertilize eggs, which they carefully attach to crevices or moss using their own silk secretions. This silk is also used for defense and suspension. Fossil evidence, including specimens found in Burmese amber, confirms that these behaviors and the lineage itself date back at least 99 million years to the middle Cretaceous, placing their divergence well before the end of the Mesozoic Era.

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