Sminthuridae - Arrhopalites caecus
Size: 0.60 mm
Group Guild Status
Eutroglophile Fungivore Uncommon?
This small, globular springtail species is known from cave and surface habitats in Europe and North America (Moore et al. 2005). We have observed it at mold sources in the cave, including mold on the wood blocks at the established invertebrate stations. Some of the sminthurids in the cave occur in wet areas, including active formations, small drip pools, and around hose bibs along the tour trails. Since we found the sminthurids at only a few of the wet habitats, and the number of individuals at these locations was always low, we did not sample at those locations. We did not anticipate that we might have more than one species in this family in the cave, and did not foresee the need to sample these minimally-populated sites. Because of our lack of sampling in these habitats we do not currently know which of these species (or possibly both) occupies wet habitats in the cave.
We suspect the wet formation biofilm food webs in the cave may be partially supported by bacteria present in autogenic meteoric waters. This small, dispersed food web type apparently contains two or possibly three macro-invertebrate species. In addition to the sminthurids we have observed small spiders in webs they constructed on wet stalagmites, where they are likely preying on the sminthurids. A third member of this biofilm food web may be the cambalid millipede, since all four of the carcasses of this species that we have found were located in this habitat type. The sminthurids were apparently present in small numbers during the time of the initial study, and the size of their population in the cave appears to be unchanged. Some populations of A. caecus in other caves are known to reproduce parthenogenetically (Moore et al. 2005).
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