The act of a lizard consuming its own shed skin, known as dermatophagy, is a regular biological event for squamate reptiles. This process of skin shedding, or ecdysis, occurs as they grow or to repair skin damage. Many lizard species, particularly geckos, actively peel and ingest their old skin. The reasons for this behavior are rooted in two fundamental biological drivers: internal recycling and external survival.
Resource Recovery and Nutrient Recycling
Shedding skin is a metabolically expensive process that demands a significant investment of the lizard’s resources. Before the old layer is sloughed off, the body synthesizes an entirely new layer of epidermis underneath, which requires substantial energy and raw materials. The shed skin is rich in biological compounds that the lizard needs to recover.
The discarded skin contains high concentrations of protein, primarily keratin, which forms the scales and outer layer. It also contains absorbed minerals and vitamins that accumulate between sheds. For female lizards preparing for egg production, recovering calcium from the shed skin is an efficient way to replenish stores needed for shell formation. By consuming the shed, the lizard reclaims these lost nutrients through its digestive system. This internal recycling mechanism helps offset the metabolic cost of ecdysis, especially in arid or resource-poor environments.
Eliminating Evidence of Vulnerability
Beyond the nutritional benefits, consuming the shed skin offers a significant advantage for survival against predators. The shedding process leaves a lizard temporarily vulnerable, as the loosened skin can impair vision and restrict movement until it is fully removed. This short period of reduced mobility makes the lizard an easier target.
The shed skin contains the lizard’s unique scent, acting as a strong olfactory signal that could attract nearby hunters, such as birds, snakes, or small mammals. By consuming the skin immediately after it is shed, the lizard eliminates this evidence from its environment. This action is a form of self-sanitation that helps conceal the lizard, reducing the risk of being tracked and attacked during a vulnerable post-shed state.
Is This Behavior Unique to Lizards
Consuming one’s own shed parts is not exclusive to lizards; it represents a broad biological strategy used across different classes of animals. Many amphibians, such as tree frogs and African dwarf frogs, also regularly ingest their shed epidermis for nutrient recovery. Organisms with exoskeletons, such as invertebrates, practice a similar form of recycling.
For instance, crustaceans like lobsters and hermit crabs consume their discarded shells, which are made of chitin and are rich in calcium. This allows them to quickly re-harden their new, soft outer layer after molting. Dermatophagy is a widespread evolutionary adaptation, demonstrating that resource conservation and concealment are universal biological pressures.