The Pac-man frog with a frog in its throat

Looking like scans of a freaky frog-shaped suitcase at airport security, the series of 3D images reveal the “frog concealment” in extraordinary detail.

Packed like some sort of amphibian Russian doll, the frog that was eaten – highlighted by the red colour – is all neatly curled inside the predatory horned frog’s stomach. All, that is, apart from its left back leg. It is still protruding out of the oesophagus, with the foot actually in the horned frog’s mouth, lying on its tongue.

This is, quite literally, a frog with a frog in its throat.

And it’s the beginning of an intriguing journey of discovery about the life and death of a museum specimen frog whose eyes may have been too big for its belly.

This accidental discovery was made by Dr Thomas Kleinteich from the Functional Morphology and Biomechanics group at the Zoological Institute of Kiel University, Germany. He generates 3D computer models of animals using a micro-CT scanner, which works in a similar way to a medical CT scanner but is designed for investigating small objects.

“Before I even had a 3D view of the specimen, I realised in a 2D section that there was something odd with the animal because it had bones where there shouldn't be bones.

“It didn't take me long to understand that it swallowed another frog species,” he tells BBC Earth.

South American horned frogs (the Ceratophrys genus) are part of Kleinteich’s current research focusing on tongue adhesion in amphibians – how frog and salamander tongues stick to prey. His research covers two main aspects: the first is the anatomy of the tongue, for example how it’s attached to the jaw and its surface structure.

Read the full article here.