What is more impressive than a walrus's tusks?

Walruses are known for their impressive tusks, but they have one anatomical feature that stands out even more.

Males of some species of mammal have a baculum, also known as a penis bone or os penis. And walruses have the largest by far, at around a metre long.

Richard Sabin, Principal Curator of Mammals at the Museum, explains what a baculum is, what it's for and why scientists think humans are one of the only primate species without it.

Find out more about bacula and their possible functions

Dive in

Find out more about life underwater and read about the pioneering work of the Museum's marine scientists.