EPOW - Ecology Picture of the Week

Safe on a Blade of Grass

Northern Dwarf Tree Frog (Litoria bicolor), Family Hylidae
Fogg Dam, Palmerston, Northern Territory, Australia

Explanation:  Night in the wetlands bordering Fogg Dam Conservation Area in northern Australia.  My headlamp suddenly spotlights a yellow blotch on a blade of grass.  At closer look, I spot ... a dwarf.

This is a Northern Dwarf Tree Frog, sitting quietly to avoid detection, although I am just an observer, not a predator.  

Indeed, the frog is doing several things to avoid detection and capture:

It has drawn in its legs to avoid a more obvious body outline, perhaps now appearing as a discolored spot on some innocuous blade of grass.

It is about the same width as the grass it is on.  This may not be coincidence but selection to, again, not pose an obvious body outline.

Is it sitting motionless to avoid detection by movement.  Predators generally have a highly evolved means of detecting motion of potential prey by sight or sound.

And it has chosen grass with ... look closely ... serrated teeth, which might deter a predator's pounce.  The grass appears similar to sawgrass of the Everglades in Florida, USA.

So this tiny amphibian has some adaptive smarts!  

And note that we have previously encountered a few other species of frog genus Litoria in Australia, including red tree frogs and green tree frogs.  

And this isn't our first encounter with dwarf flora and fauna ... having found yellow-headed dwarf geckos, dwarf crocodiles, dwarf louseworts, and even dwarf spiders!