Functional morphology as an aid in determining trophic behaviour

Abstract

The arthropod communities of phytotelmata (plant-held waters) are considered excellent subjects for studying and testing community theory. Food webs constructed for phytotelm communities, however, usually exclude mites or determine their placement based on little, if any, actual knowledge of their trophic behaviour. Although individually small, many acarine species attain high population levels and therefore may be important as prey for other inhabitants, as processing chain species in commensal relationships and as competitors of the larger tree hole inhabitants. An understanding of the trophic relationships of acarine inhabitants is therefore essential to an understanding of the dynamics of phytotelm communities. Studies emphasizing the functional morphology of mouth-parts of astigmatic species inhabiting water-filled tree holes in the eastern USA and in Queensland, Australia, reveal a diversity of trophic groups. Among these are ‘shredders’ who ingest leaf material and associated microbes by biting off chunks of leaves, ‘scrapers’ (= grazers) who crop fungal hyphae and/or other microbes and detritus from the substrate surface, and ‘collectors’ who filter microbes and fine particulate matter from the water. This information allows for the more exact placement of acarine inhabitants in food webs of water-filled tree holes.