When You Notice A Whitish Strange Thing on the Branch

Chameleons' Paired Hemipenes: Function, Ornamentation, and Shedding Dynamics

Chameleons possess unique reproductive organs known as hemipenes, which serve the primary function of delivering sperm during mating. Unlike mammals, chameleons have paired hemipenes, allowing for the introduction of sperm from either side during copulation. These structures are anatomically designed to be filled with lymph, reflecting their ectodermal origin, as they develop from the epidermis.

The hemipenes are often elaborately ornamented, featuring spines, hooks, or lobes that aid in the anchoring and transfer of sperm. They are typically shed in conjunction with the epidermis during ecdysis, the process of molting. On the day of shedding, the exuviae (molted skin) are expelled alongside fecal matter; during this defecation process, the hemipenes may also evert, pushing them out to ensure cleanliness and readiness for subsequent mating opportunities.

While hemipenes can be shed separately, healthy chameleons usually expel them together in one piece if hydration is optimal. If hemipenes are not shed properly, they may become non-functional. This can lead to complications such as the inability to evert (protrude) the hemipenes, disrupting mating behavior. Furthermore, retained plugs may develop, potentially obstructing the hemipenes and hindering reproductive success. Thus, the proper physiology and shedding of hemipenes are critical for maintaining reproductive health in chameleons.

The poctire depitcs the physiological hemipeneal shed in an adult captive Furcifer pardalis,
Photos courtesy Todd Arban