It's a Frog Eat Frog World - Scientist Finds Frog Inside a Frog During CT Scan

by Victoria Heuer

If you have ever eaten much more at the dinner table than you had planned to and felt fit to burst, then you know how this frog felt just before it died.

In a paper titled "To have a frog in the throat: micro-CT imaging of anuran prey in Ceratophrys ornata," published in the June 2015 issue of Salamandra - German Journal of Herpetology, Dr. Thomas Kleinteich, of the Zoological Institute at Kiel University, Germany, describes finding a fully intact frog inside the digestive cavity of an Argentine Horned Frog, scientific name Ceratophrys ornate, using micro-CT imaging.

Colloquially known as “Pac-Man” frogs, Ceratophrys have the advantage of being able to open their mouths wide enough to swallow their prey whole into a belly that takes up most of its body mass — hence the Pac-Man moniker.  

They also have the advantage of patience. Ceratophrys are “sit-and-wait” predators, sitting motionless and hidden until a prey animal comes close enough for the ambush, as opposed to those animals who stalk and chase their prey.

Like all frogs, frogs of the Ceratophrys group are carnivores. But while smaller frogs generally limit themselves to insects, spiders, and small crabs, these larger Ceratophrys frogs, with their larger mouths and bellies, are able to feed on larger animals as well, like snakes, rodents, lizards, and even other species of frogs.

In this case, the female Horned Frog had eyes bigger than her belly. The prey frog, which was identified as a Lithobates pipiens, or Northern Leopard Frog, was found headfirst in the stomach of the Horned Frog, with its left leg still sticking up through the Horned Frog’s esophagus, and its foot resting on her tongue. The Leopard Frog was measured to be more than half the Horned Frog size, and the cause of death for the Horned Frog is presumed to be blockage of the airways.

_{Image Credit: Dr. Thomas Kleinteich, Kiel University}

The Northern Leopard Frog is found in Canada and the United States, while the Argentine Horned Frog, as its name suggests, is found in Argentina, Uruguay and Brazil. The Horned Frog had been donated to the Zoologisches Museum Hamburg in Germany and was being housed in its collection, but there were no records about where the frog had come from, or how two frogs that come from different parts of the world came to be in the same environment. It is assumed that they were held in captivity together.    

Source: Salamandra - German Journal of Herpetology, Issue 51, June 2015

Main image: Aleksey Stemmer / Shutterstock