Based on how the insects breathe under water, insects are split into
two general categories of respiration: Apneustic and Hydropneustic.
Aeropneustic (Aero = air, pneustic = breath) aquatic insects include the submerged or partially submerged species that breath atmospheric air. Surface breathers include insects that use breathing tubes that are extended above the water surface while the remainder of the insect stays submerged. Common examples of insects that use this method include water scorpions (Hemiptera) and rattailed maggots (a fly). Other insects trap air at the surface and then dive beneath the water surface, carrying an air supply with them. Like a scuba tank, when the stored air is depleted, the insect must return to the surface to resupply. Common examples of insects using this method include Diving Beetles (Coleoptera) and backswimmers (Hemiptera). A third type of Apneustic respiration: endophytic respiration is used by insects which tap into plants and breath atmospheric air through the stems. This unusual strategy is found in a few species of mosquitoes and aquatic leaf beetle larvae.
| The other major respiratory category, Hydropneustic (Hydro = water, pneustic = breath) respiration, is found in insects that obtain their oxygen needs from the water. Since most insects are small, the majority can obtain some oxygen directly across their exoskeleton. This is termed "cuticular respiration" and often insects and heir larvae have special areas of their exoskeleton that allow diffusion. But, as insects get larger or move more, diffusion is no longer able to supply enough oxygen. Many insects have special flaps of very thin membranes that extend from their bodies. These membranes are called gills and they increase the surface area and thus, the oxygen supply. The main insect orders (Odonata, Ephemeroptera, Trichoptera, and Plecoptera) that are exclusively aquatic all have gills as larvae. |
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A rattailed maggot
B diving beetle C mayfly larva D mosquito larva E water strider |
