Competition has led to the males having the largest testes relative to their body weight for any known mammal, being 4.2%.

Male hamsters typically have very large testes in relation to their body size.

Macroorchidism is a genetic disorder found in males where a subject has abnormally large testes.

For instance, the large testes of the tanuki character were removed for the North American edition.

Chimpanzees have the largest testes of the primates relative to body size.

Chimpanzees have high promiscuity and large testes compared to body weight (0.3%).

Males have large testes in relation to their body size.

It is a conspicuous organ, being colored red, and at the cranial poles of the large testes.