EPOW - Ecology Picture of the Week

Rockhole Frog

Rockhole Frog (Litoria meiriana), Family Pelodryadidae
Litchfield National Park, Northern Territory, Australia

Explanation:  I found this tiny amphibian, well, literally in a hole in a rock.  And yes, this is a rockhole frog, so-named because it is quite often found in rock outcrops associated with seeps, springs, pools, and creeks.   

Rockhole frogs are tiny.  Tadpoles can reach about an inch (2.5 cm) in length ... but once transformed and they lose the tail, adults achieve only about 0.8 inch (2 cm) in length, about the width of your thumb.

Rockhole frogs belong to the family Pelodryadidae that is found in Australia and New Guinea.  The genus Litoria is commonly referred to as Australian treefrogs ... ha, except for this one that inhabits rock holes or such environments.

Some sources cite this species as being small and agile enough
to be able to skip over the surface of the water like a skimming rock.

Frogs typically avoid dry heat and sun.  Rockhole frogs, however, tolerate direct sun by finding moist places to rest.  Studies (Tracy et al. 2012) have even shown that they can maintain more than 95% of their hydrated condition, but during hot afternoons it can fall to as low as 85%, or even temporarily to near-lethal conditions of about 70%, and that they cool by evaporation.  So their bigger threat is desiccation -- drying out -- more so than just overheating.

I found this individual after hiking into a somewhat remote corner of Litchfield National Park called the historic Blyth Homestead, way up in "Top End" Northern Territory of Australia.  The species is endemic to Australia, and to this Top End corner of the country.  

The species is listed by IUCN as Least Concern.

Information:
     Tracy, C.R., K.A. Christian, N. Burnip, B.J. Austin, A. Cornall, S. Iglesias, S.J. Reynolds, T. Tixier, and C. Le Noene.  2012.  Thermal and hydric implications of diurnal activity by a small tropical frog during the dry season.  Austral Ecology 38(4):476-483.