The diving bell and the spider: the physical gill of Argyroneta aquatica

Abstract

SUMMARYArgyroneta aquatica is a unique air-breathing spider that lives virtually its entire life under freshwater. It creates a dome-shaped web between aquatic plants and fills the diving bell with air carried from the surface. The bell can take up dissolved O 2 from the water, acting as a 'physical gill'. By measuring bell volume and O 2 partial pressure (P O2 ) with tiny O 2 -sensitive optodes, this study showed that the spiders produce physical gills capable of satisfying at least their resting requirements for O 2 under the most extreme conditions of warm stagnant water. Larger spiders produced larger bells of higher O 2 conductance (G O2 ). G O2 depended on surface area only; effective boundary layer thickness was constant. Bells, with and without spiders, were used as respirometers by measuring G O2 and the rate of change in P O2 . Metabolic rates were also measured with flow-through respirometry. The water-air P O2 difference was generally less than 10kPa, and spiders voluntarily tolerated low internal P O2 approximately 1-4kPa before renewal with air from the surface. The low P O2 in the bell enhanced N 2 loss from the bell, but spiders could remain inside for more than a day without renewal. Spiders appeared to enlarge the bells in response to higher O 2 demands and lower aquatic P O2 .

Superwettability of Gas Bubbles and Its Application: From Bioinspiration to Advanced Materials

“…[24] In fact, several insects hiding or hunting underwater exploit the property of superaerophilicity. [25][26][27][28][29] Water spiders…”

“…Reproduced with permission. [25,26] Copyright 2011 and 2013, The Company of Biologists Ltd and Springer-Verlag. c) The silvery shine of an air plastron trapped in numerous micro-sized hairs on the body surface of a water boatman.…”

“…Attributed to the spiders' wax-coated feather-like hairs, air bubbles are anchored firmly and superaerophilicity is exhibited. [25,26] When the water boatman (Notonecta glauca) is resting directly beneath the water/air interface, the silvery shine of an air film on the elytra is clearly visible. A large volume of air is trapped in their numerous curving micro-sized hairs (Figure 1c).…”

Physical gills prevent drowning of many wetland insects, spiders and plants

“…Similarly, although restricting roaming range, dive bells also enable prolonged periods underwater. A recent study applying modern O 2 -sensing techniques has improved understanding of dive bell functioning (Seymour and Hetz, 2011). The Eurasian dive bell spider (Argyroneta aquatica) builds a silk dome underwater attached to submerged vegetation, which it fills with air via repeated trips to the surface.…”

Explosions at the water surface

“…The critical velocity at which a cavity appears depends on both the shape and wetting properties of the solid . The underlying applications include the impact of bullets (May 1952), torpedoes (May 1975), but also water walking lizards (Glasheen & McMahon 1996) and spiders: the diving Argyroneta aquatica entrains air with its body to build an underwater bell and survive (Seymour & Hetz 2011). The different types of cavities are classified in the phase diagram presented in figure 1, where the velocity is rescaled by η/ρR on the horizontal axis, and the size by the capillary length a = √ γ /ρg on the vertical one.…”