Diving Bell Spider

Argyroneta aquatica is the only known spider species that spends its entire adult life submerged in fresh water. Found across Eurasia in still and slow-moving water with abundant aquatic vegetation, the diving bell spider constructs a dome-shaped web of silk anchored to underwater plants. The spider then makes repeated trips to the surface, trapping a film of air against the dense hairs on its abdomen and legs (a 'plastron'), and bringing the air down to deposit inside the silk dome. The accumulated air inflates the dome into a glittering silver bell — the species' common name comes from this gleaming structure. Inside the bell, the spider rests, hunts ambush-style, mates, lays eggs, molts, and overwinters. A 2011 study published in the *Journal of Experimental Biology* demonstrated that the silk wall functions as a literal physical gill: oxygen diffuses inward from the surrounding water and carbon dioxide diffuses outward. A spider can remain inside the bell for over 24 hours without surfacing. Females are larger than males in this species (a reversal of the typical spider pattern), and males build smaller bells adjacent to females during mating season.