These frogs are exclusively aquatic and have numerous morphological modifications befitting their habitat. For example, the feet are completely webbed, the body is flattened, and a lateral line system is present.
The fossil record for pipids is relatively good with twelve extinct species known. Six of these are placed in the extant genus Xenopus, the remainder in extinct genera. These fossils are known from Africa, South America, and Middle East back to the Lower Cretaceous.