Reptile & Amphibian Forums

Due to the fact that many lizards and amphibians are purely insectivorous I am curious as to whether or not they are able to digest chitin. I have read (in my biochemistry text) that since chitin is similar to cellulose that vertebrates are unable to digest chitin. Yet looking around I have noticed that some studies are being done that show that some sea birds and definitely bacteria can digest chitin. Is there any evidence of a symbiosis with bacteria that allows for digestion of chitin? Is there any evidence of chitinases in the various insectivorous herps? I am just beginning to explore this idea and just wanted to throw it out and see what kind of thoughts are floating around out there. Thanks in advance for you responses.

Bryan

Just from observation as a reptile keeper, I would say they can't. Chitin is expelled in the droppings in tiny sand-like particles with occasional larger fragments. Reptile digestive systems appear vigorous enough to break up even hard-shelled insects that are swallowed whole, but the chitin seems to pass through their system in quantity.

Yeah, I agree that just from observations they do not digest very much. But, what if they are able to digest chitin small amounts. Chitin is basically modified glucose, very similar to cellulose, and in my mind it just seems like such a waste if no vertebrate has an ability to digest it. Nature is an amazing thing and does not like to waste. Animals have found a way (with the help of gut flora) to digest cellulose. Why not chitin. That is where my thoughts develop. That is why I ask the question here to see if there is any salient research on this topic at this point. I know that there have been studies in other vertebrates such as birds and mammals, but like everyone on kingsnake herps are my passion so that is where I would like to really do some studying up on the subject. Thanks for your response.

Bryan

According to Tremper and De Vosjoli's new leopard gecko book, these geckos, and most (but not all) other insectavorous lizards do produce chitanase, and are able to break it down to some degree. As to what level digestion of chitin occurs is not stated, but they did state that they feed even hatchling geckos mealworms (Tenebrio molitor) which I do not think could be passed without some breakdown of the chitin. I don't know where they collected the data, but at least that is a place to start looking.

Hope it helps...

Jono

What references were given in the back of the book?
Just because they dispelled the myth that hatchlings cannot do well on mealworms doesn't mean that chitinase is involved.

An interesting experiment would be to collect gastric and intestinal samples and incubate them with chitin products contained withen. If chitinase of some sort were present than the gastric and/or duodenal samples would show some signs of chitin break down over time. If a symbiosis were involved, it would most likely occur in the later ends of the intestine. If this were to be the case, methods killing all the flora in the samples could be tested to see if breakdown of chitin still occured in a sterile sample (thus indicating that chitinase was released outside of the usual pancreatic fluids)

Let us know what you find
Ian

In other insectivores, the ability to digest chitin is species dependent and/or can be the result of bacteria inhabiting the gut.

Ed