They are responsible for more human deaths than any other animal in Africa.
However, they are not alone in having internal testes.
Undescended testes is a basal characteristic in mammals that is unchanged in monotremes (platypus and echidna), some insectivores, xenarthrans (sloths, anteaters, and armadillos) as well as elephants. In these species, the testes remain deep in the abdomen.
Descended but ascrotal testes are found in hippos, tapirs, rhinos, and some bats. These move closer to the body surface but don’t make the final trip outside.
And there are some mammals that only have scrotal testes during breeding season, such as squirrels, some bats, and some primates. Testes housed indoors otherwise.
Probably more than anyone wanted to know, but there you are.
