Respiratory function of the plastron in the aquatic bug Aphelocheirus aestivalis (Hemiptera, Aphelocheiridae)
| dc.contributor.author | Seymour, R. | |
| dc.contributor.author | Jones, K. | |
| dc.contributor.author | Hetz, S. | |
| dc.date.issued | 2015 | |
| dc.description.abstract | The river bug Aphelocheirus aestivalis is a 40 mg aquatic insect that, as an adult, relies totally on an incompressible physical gill to exchange respiratory gases with the water. The gill (called a 'plastron') consists of a stationary layer of air held in place on the body surface by millions of tiny hairs that support a permanent air-water interface, so that the insect never has to renew the gas at the water's surface. The volume of air in the plastron is extremely small (0.14 mm³), under slightly negative pressure and connected to the gas-filled tracheal system through spiracles on the cuticle. Here, we measure Po₂ of the water and within the plastron gas with O₂-sensing fibre optics to understand the effectiveness and limitations of the gas exchanger. The difference in Po₂ is highest in stagnant water and decreases with increasing convection over the surface. Respiration of bugs in water-filled vials varies between 33 and 296 pmol O₂ s⁻¹, depending on swimming activity. The effective thickness of the boundary layer around the plastron was calculated from respiration rate, Po₂ difference and plastron surface area, according to the Fick diffusion equation and verified by direct measurements with the fibre-optic probes. In stagnant water, the boundary layer is approximately 500 μm thick, which nevertheless can satisfy the demands of resting bugs, even if the Po₂ of the free water decreases to half that of air saturation. Active bugs require thinner boundary layers (∼ 100 μm), which are achieved by living in moving water or by swimming. | |
| dc.description.statementofresponsibility | Roger S. Seymour, Karl K. Jones and Stefan K. Hetz | |
| dc.identifier.citation | Journal of Experimental Biology, 2015; 218(18):2840-2846 | |
| dc.identifier.doi | 10.1242/jeb.125328 | |
| dc.identifier.issn | 0022-0949 | |
| dc.identifier.issn | 1477-9145 | |
| dc.identifier.orcid | Seymour, R. [0000-0002-3395-0059] | |
| dc.identifier.uri | http://hdl.handle.net/2440/100704 | |
| dc.language.iso | en | |
| dc.publisher | Company of Biologists | |
| dc.relation.grant | ARC | |
| dc.rights | © 2015. Published by The Company of Biologists Ltd | |
| dc.source.uri | https://doi.org/10.1242/jeb.125328 | |
| dc.subject | Aquatic insect; metabolic rate; optode; oxygen; respiration; spiracle; tracheal system | |
| dc.title | Respiratory function of the plastron in the aquatic bug Aphelocheirus aestivalis (Hemiptera, Aphelocheiridae) | |
| dc.type | Journal article | |
| pubs.publication-status | Published |