Episode 88: Bacula
The buculum is a bone present in the head of the penis of most mammals. Whilst a few mammals, like us, don’t possess a baculum, some have greatly reduced versions and many have very elaborate shapes. Despite this variety in expression of the baculum, its function remains elusive, though many theories exist.
Investigating the function of this bone is Dr Charlotte Brassey, Manchester Metropolitan University, UK, and she joins us for this episode to give us a crash course on penile anatomy and to reveal to us how little we know about genitals.
Podcast: Download (Duration: 48:19 — 67.3MB)
MicroCT data of the penis of a snow leopard (top) and red panda (bottom). This image shows how the relative size of the baculum (red) can vary between mammals.
Dorsal and ventral views of the penis of the fossa. Note the well-developed spines present on the glans tissue these are thought to trigger ovulation as opposed to discouraging the female from reproducing again. Spines are present in a number of other mammals, including chimpanzees.
MicroCT scanning of a walrus baculum. Scanning conducted at Manchester X-ray Imaging Facility, in the Nikon Custom Bay. The baculum was so large that five separate scans had to be stitched together to get the final picture.
Bacula can be quite common in museum collections. Tray full of sea otter bacula at the Smithsonian Institution, USA.
Penis and testes of an adult male chimpanzee. The testes are also an important part of the male reproductive system. The testes are typically larger in the species in which males mate with multiple females. There is also a correlation in testes size and baculum length in animals such a pinnipeds (seals, walruses, sea lions, etc.).
