Physical gills in diving insects and spiders: theory and experiment

Abstract

. However, some diving species take a tiny air-store bubble from the surface that acts as a primary O 2 source and also as a physical gill to obtain dissolved O 2 from the water. After a long history of modelling, recent work with O 2 -sensitive optodes has tested the models and extended our understanding of physical gill function. Models predict that compressible gas gills can extend dives up to more than eightfold, but this is never reached, because the animals surface long before the bubble is exhausted. Incompressible gas gills are theoretically permanent. However, neither compressible nor incompressible gas gills can support even resting metabolic rate unless the animal is very small, has a low metabolic rate or ventilates the bubbleʼs surface, because the volume of gas required to produce an adequate surface area is too large to permit diving. Diving-bell spiders appear to be the only large aquatic arthropods that can have gas gill surface areas large enough to supply resting metabolic demands in stagnant, oxygenated water, because they suspend a large bubble in a submerged web.

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…”

“…[59,60] The smaller the interface curvature, the smaller the diameter of spherical crown-shaped gas-bubble is captured. [44] Cu 3 P microsheets (lateral size: 6 µm, thickness: 510 nm) [46] Amorphous MoS 2 porous thin film constructed by nanosheets with the size of several micrometers [50] Pine-shaped Pt nanoarray [27] HzOR Vertically aligned Cu nanoplate array (average size: 500 nm, thickness: 50 nm) [31] Ultrathin Ni nanosheet arrays (2.2 nm) [44] Ni nanoflower electrodes [45] 3D porous Ni-Cu alloy film (400 nm flower-like nanostructure) [51] ClER RuO 2 @TiO 2 nanosheet array (irregular sheet-like units with lateral size 200 nm and thickness 20 nm) [47] OER Cu 3 P microsheets (lateral size 6 µm; thickness 510 nm) [46] NiFe-LDH nanoplates (500 nm) vertically grown on Ni foam [48] Zn x Co 3−x O 4 nanostructures constructed with secondary nanoneedles grown on primary rhombus-shaped pillar arrays (pillar length 15 µm) [52] Core-shell-structured Ni 2 Co 1 @Ni 2 Co 1 O x powder (nanoparticle diameters over 50 nm) [53] observations and scanning electron microscope (SEM) images of thicker, porous, skeleton structures on superaerophilic sponge. Numerous pores with sizes of up to hundreds of micrometers exist in the sponge.…”

“…However, the air-film persistence of such an interface is relatively low, probably because it can only withstand low water pressures. [27][28][29] When the floating water ferns Salvinia molesta are submerged in water, they are capable of holding an air layer for several weeks, presumably limited by their lifetime. The eggbeater-shaped structures very efficiently act as pillars supporting the air-water interface (tent-like), preventing it from further approaching the leaf surface.…”

It's Not a Bug, It's a Feature: Functional Materials in Insects

“…Insects are also often constrained to highly oxygenated aqueous environments. [194] It then follows that river bugs are likely one of the largest groups of plastron insects. [192] They are shaped to have a high surface-area-tovolume ratio, they have resting metabolic rates less than half of what is predicted for their size, and they are most commonly found in moving, well-aerated streams.…”

Preparations of the Artificial Plastron Device by Self-Organized Honeycomb-Patterned Films

“…However, air bubbles are supported by superhydrophobic hairs, so air bubbles can not become small and O 2 is supplied from water by a partial pressure. As result, insects can continuously stay in water by using plastrons as physical gills [5]. By mimicking the plastron, we can obtain new oxygen supply device instead of limited air cylinder for use in water [6].…”