Adaptations to Life Under Water: Tiger Beetles and Millipedes

An adaptation is an attribute of an organism that enhances survival and reproduction in the biotope which it inhabits (cf. Schaefer 1992). In Amazonian floodplains, many terrestrial invertebrates show adaptations which enable them to live in a periodically flooded ecosystem. Two animal groups have been selected to exemplify different survival strategies, the tiger beetles and the millipedes. The tiger beetle Megacephala (Tetracha) sobrina punctata Laporte from varzea floodplains is amphibious and its adaptations are of an ecoethological, ecophysiological, and morphological nature. Many terricolous millipedes of Central Amazonian floodplain forests, including Polydesmida, migrate from the soil into the trunk/canopy where they pass the aquatic phase of 5–7-months duration (Adis 1992a; Adis et al. 1996a). Some polydesmidan species, however, show a “flooding ability” which ranges from a few hours or days (submersion tolerance) up to several weeks or months (submersion resistance); this is possible due to plastron respiration (Messner 1988) under water.