Why Frogs Shed Their Skin

I was watching my wild toad outside when I was a kid one Summer morning and honestly thought it was choking and dying. It was rubbing its head and opening its mouth in a very strange way I had never seen before. However, after acute observation, I realized the toad was just shedding its dead skin and eating it.

Shedding, otherwise known as sloughing or moulting is a process where frogs shed, remove, and eat their dead skin. This process may ressemble choking, however it is a natural occurence for frogs and toads.

Sloughing helps frogs maintain optimal body functions, uphold crucial protective barriers, lower the load of potentially harmful pathogens, and cover their tracks. Frogs routinely eat their dead skin after shedding, as the skin contains numerous healthy proteins and nutrients. 

As strange as it may seem, shedding skin (and eating it) is a common practice among amphibians in general. Frogs have incredibly porous and sensitive skin which plays a vital role in homeostasis and immune system defence. Shedding skin and eating it can assist a frog in numerous ways that I will explain in this article.

1. Frogs Shed And Eat Skin for Cell Renewal 

Renewing the skin through periodic moulting and sloughing is a key aspect of amphibian behaviour. The sloughing process gives way for new, fresh, and healthy skin cells. Ensuring that their skin is healthy and strong all year round greatly increases the strength of the skin’s chemical, cellular, and physical barriers (Varga JFA et al. 2019).

Like many other animals, such as other amphibians or reptiles, skin renewal is the primary purpose of skin sloughing. Skin sloughing has a massive impact on overall epidermal turnover, supporting these amphibians’ primary layer of self-defense. 

2. Frogs Shed And Eat Skin for Optimal Bodily Functions

Dead or weak skin cells can cause a range of health issues for any animal, but frogs are extremely vulnerable to skin problems. They also use their skin for breathing and drinking, meaning that a lack of skin functionality could lead to dehydration and other complications. 

Most frog species use their skin for water uptake, ion transference, predator deterrence, heat transfer, camouflage, and much more. Routinely shedding dead skin cells and allowing new skin cells to take their place greatly supports these bodily functions, allowing them to thrive in the wild.  

3. Frogs Shed And Eat Skin to Lower Pathogen Loads

Despite differences between species, all amphibian skin plays a crucial role in their defence mechanisms. Their skin is the primary form of defence against intrusive pathogens, and bacteria.

Although skin renewal is generally the primary and immediate purpose for shedding skin, the process of skin sloughing typically helps control cutaneous microbial populations as well (Michael E. et al. 2019). Since frogs have such sensitive skin, controlling potentially harmful microbes on the skin is extremely beneficial to their overall longevity. 

When frogs shed their skin, they lower the load of potentially harmful bacteria, pathogens, fungus, germs, and other threats to the immune system. Since these pathogens generally reside on the skin’s surface, removing the skin has a fair chance of removing many of these germs. 

Although skin sloughing does not typically remove all harmful bacteria, it has been scientifically proven that skin sloughing has been effective at reducing pathogen loads on a broad scale. This scenario has proven true concerning Batrachochytrium dendrobatidis (Bd), which is a lethal fungus to frogs.

4. Frogs Shed And Eat Skin to Cover Their Tracks

It is common for amphibians to routinely eat their dead skin once they have removed it from their body (Weldon et al. 1993). Frogs are incredibly smart creatures and use this technique to cover their tracks from predators to help ensure their overall survival.

As a result, they do not simply leave their sloughed skin behind like many other animals might. Frogs tend to eat it to take it out of their environment and make it seem like they were not in the location where they moulted their skin.

5. Frogs Shed And Eat Skin For Nutrients

While eating their skin after shedding may seem incredibly strange and complex, frogs simply recycle their waste. Their skin houses numerous healthy proteins and nutrients, which can be worth consuming and absorbing from the inside. 

Most of the components used to produce the skin’s outer layer will be returned to the frog’s body as it pushes the dead skin down its throat after shedding. This method is incredibly beneficial for frogs living in the wild, as it provides them with extra nourishment without the need for hunting. 

How Do Frogs Shed Their Skin?

The timing and duration of skin shedding processes differ substantially but many pet frog owners have observed their frogs sloughing in the morning. Timing and duration are typically uniform within the same species but differ between families and groups. However, most anuran species generally use similar practices and approaches to complete the task.

Some species inflate their bodies with air before sloughing, while terrestrial frogs use more lateral movement of the entire body since they generally have shorter limbs. Some frog species slough their skin from an elevated area, such as a wall or vertical surface. 

During the sloughing process, the keratinized outer layer of the skin (formally referred to as stratum corneum) is shed in one single piece. The process of shedding occurs in a specific series of body and limb movements, which loosens the outer skin layer allowing it to slide off with ease (CTNF).

Although it may look like a frog or toad is choking while they are moulting or sloughing, they are perfectly fine.

Do All Frogs Shed Their Skin The Same Way?

The variation in frogs shedding their skin is notable, as the rate and frequency of sloughing generally differ between species. While there are still many questions needing scientific answers, it has been assumed that these differences in sloughing habits may be closely related to differences in the following areas:

  • Skin cell turnover rates
  • Ecological traits
  • Skin morphology
  • Phylogenetic positions

Keep in mind that there are over 7,400 known frog species in the world. So different types of frogs shed at varying rates, ranging from daily to weekly or even nightly in some cases. While many physical aspects and composition features are similar, frogs’ skin may still differ in thickness, mucosal glands, peptide glands, and sculpturing. 

There may be differentiations in additional structures such as dermal layers, which may be postulated to help resist cutaneous water loss. The number of epidermal layers may also contribute to different frog species’ necessity for sloughing, as more epidermal layers typically create more flexibility and increased sloughing rates.

More About Frog Skin

Shedding the skin is incredibly important for frogs, as it helps them maintain proper bodily functions and defend themselves from potentially harmful microbes. It may seem strange for frogs to peel off their skin and shove it into their mouth, but these little creatures are simply being resourceful to ensure their survival (CTNF).

Frogs need to shed or slough their skin to ensure that the skin can continue ongoing processes with optimal efficiency, keeping them safe and healthy throughout their lives. Learn more about frog skin on our blog:

Sources

Weldon, Paul J., et al. “A Survey of Shed Skin-Eating (Dermatophagy) in Amphibians and Reptiles.” Journal of Herpetology, vol. 27, no. 2, Society for the Study of Amphibians and Reptiles, 1993, pp. 219–28, https://doi.org/10.2307/1564942.

Varga JFA, Bui-Marinos MP, Katzenback BA. Frog Skin Innate Immune Defences: Sensing and Surviving Pathogens. Front Immunol. 2019;9:3128. Published 2019 Jan 14. doi:10.3389/fimmu.2018.03128

Michel E. B. Ohmer, Rebecca L. Cramp, Craig R. White, Peter S. Harlow, Michael S. McFadden, Andrés Merino-Viteri, Allan P. Pessier, Nicholas C. Wu, Phillip J. Bishop and Craig E. Franklin. Phylogenetic investigation of skin sloughing rates in frogs: relationships with skin characteristics and disease-driven declines. 06 February 2019 https://doi.org/10.1098/rspb.2018.2378