PORCELLIONIDAE - Porcellio laevis
Size: Up to about 14 mm
Group Guild Status
Eutroglophile Scavenger Common
P. laevis is an introduced species from southern Europe that is common and widespread in the United States and Canada (McLaughlin et al. 2005; Muchmore 1990). This species is essentially an epigean animal, occurring among surface debris, beneath rocks, and in the epikarst. It is relatively common in the less humid portions of the cave near surface connections, where they enter the cave to forage. The species has been recorded primarily in the entrance series of rooms near the historic Entrance Sink and as far into the cave as Grand Central Station and the southern half of Main Corridor. It is also found in the Scorpion Passages and at Granite Dells, each of which have their own connections with the surface. We seldom encountered juveniles of P. laevis, and the animals typically do not go deep into the cave. However, a clutch of very small individuals was found on a ringtail scat in the Scorpion Passages during a post-study visit to the cave on May 31, 2012. Based on this evidence some of the animals apparently do breed in the cave.
Single adults were found near and on the Maternity Roost guano deposit on November 11, 2009 and April 17, 2010 respectively. The initial study also noted that this species was seldom observed in the vicinity of the guano deposits. They are apparently opportunistic generalist scavengers that regularly enter the cave from the surface to make use of food resources that occur in cave entrance areas. We suspect that this species seldom breeds in the cave, but evidence that it can reproduce in the cave and may occasionally complete generations within the cave, makes it a eutroglophile.
There is very little overlap in the distribution of the two isopod species in the cave. Brackenridgia prefers interior, moister regions of the cave and P. laevis is typically found closer to entrances. Brackenridgia is probably intolerant of less humid atmospheres and drier surface conditions, while P. laevis is apparently tolerant of a wider range of environmental conditions. We suspect that the main reason that P. laevis does not often occur in the deeper regions of the cave is that it is essentially a surface and epikarst species. They forage in cave entrance areas simply because these areas are integrally connected with their typical habitat.
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