Macroarthropods

Larger insects, spiders, myriapods, and others are considered together under the appellation "macroarthropods." Typical body lengths range from about 10 mm to as much as 15 cm for centipedes (Shelley, 2002). The group includes a mixture of various arthropod classes, orders, and families. Like the microarthropods, the macroarthropods are defined more by the methods used to sample them rather than by measurements of body size. Large soil cores (10-cm diameter or greater) may be appropriate for euedaphic (dwelling within the soil) species. Arthropods can be recovered from them using flotation techniques (Edwards, 1991). Hand sorting of soils and litter is more time consuming, but yields better estimates of population size. In rare instances, capture-mark-recapture methods have been used to estimate population sizes of selected macroarthropod species, but the assumptions for this procedure are violated more often than not (Southwood, 1978). Pitfall traps have been widely used to sample litter- and surface-dwelling macroarthropods. This method collects arthropods that fall into cups filled with preservative. Absolute population estimates are difficult to obtain with pitfall traps but the method yields comparative estimates when used with caution.

Many of the macroarthropods are members of the group termed "cryptozoa," a group consisting of animals that dwell beneath stones or logs, under bark, or in cracks and crevices. Cryptozoans typically emerge at night to forage, and some are attracted to artificial lights. The cryptozoa fauna is poorly defined but remains useful for identifying a group of invertebrate species with similar patterns of habitat utilization.

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