EPOW - Ecology Picture of the Week

Clawed Frog in Hell's Gate

Northern Clawed Frog (Xenopus borealis), Family Pipidae
Hell's Gate National Park, Kenya, Africa

Explanation:  What is this strange amphibian found in a cool canyon stream in the Rift Valley of Kenya, eastern Africa?  

It is a northern clawed frog in its native habitat, here in the strikingly-named Hell's Gate National Park. 

Clawed frogs of genus Xenopus are one of the mostly widely sold and distributed laboratory research animals ... beginning their "scientific career" in the 1940s when it was discovered that urine from a pregnant woman, injected beneath the skin of a female clawed frog, would induce the frog to lay her eggs, thus serving as an easy pregnancy test.  These days, they are common laboratory animals used to study embryology because their embryos are transparent.  They are also the first vertebrate ever to be cloned in the lab.

Clawed frogs are also mainstays of the pet trade.

But they are also serious pests, having been introduced to waterways all over the world.  Largely carnivorous on invertebrates, but also with a scavenger diet, they eagerly eat all manner of prey including many native species ... despite the fact that this family of frogs lacks a tongue but has an acute sense of smell and very sensitive digits to sense and seek out prey.  Stranger is the absence of visible ear openings or coverings (called "tympanum" in other frogs), and the presence of a sensitive "lateral line" by which to detect presence of prey.   
  

Note the many small white skin folds on the sides; these are sensory
organs, sometimes described as looking like stitches, that serve
as a lateral line to allow clawed frogs to sense prey even 
in water too murky to see.

 
Males have a very loud call although they lack vocal cords, and produce loud clicking sounds by contracting their throat muscles.  

The genus name Xenopus means "strange foot" because the hind feet have sharp claws on extra-long webbed toes.  
 

  Like a fish out of water, clawed frogs are entirely aquatic, but 
unlike fish they breath using lungs.  I returned this specimen safely to its
stream habitat shortly after taking a few quick photos.