[2] Its name refers to the very large—up to 27 cm (11 in) long—tadpole (the world's longest), which in turn "shrinks" during metamorphosis into an ordinary-sized frog, only about a quarter or third of its former length.

[3][4][5] The species inhabits ponds, lakes, lagoons and similar waters from the Amazon and the Guianas, to Venezuela and Trinidad, with a disjunct distribution in the Magdalena River watershed in Colombia and adjacent far western Venezuela.

[6][7] More southerly populations from the Pantanal region to northeastern Argentina have been recognized as a subspecies, but are now often considered a full species, P. platensis,[6] although the validity of this split is questionable.

[8][9] When threatened, the frog uses its strong toes with an extra joint to stir up the muddy bottom and hide.

In March 2008, scientists working from the Universities of Ulster and United Arab Emirates released findings of a study on pseudin-2, a skin compound which protects the paradoxical frog from infection.