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Carapace Pitting in Terrapene - Darrell Senneke

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Copyright © 2003 World Chelonian Trust. All rights reserved

One of the most common health questions relating to wild caught captive American box turtles relates to the presence of small pits on the carapace.   These are most typically found in Three-toed Box turtles, Terrapene carolina triunguis.  

There are a number of different reasons given anecdotally for the presence of these pits.  One of the most prevalent of these is that they are the result of the use of tongs by hunters as they dragged the turtle out of its hibernation quarters or its burrow.  While this supposition is attractive as it both calls attention to the collection of a species in the wild and the related cruelty of the same it has no bearing in fact.  Yes, Terrapene are collected from the wild, often in non sustainable numbers and yes this is a practice that we do not support in any way. The usual placement of the pits as well as the presence of many of these on specimens examined in the wild lays that theory to rest.  As further evidence against this theory is the fact that wild Terrapene are collected in numbers generally by picking them up from country roads after rain or by using dogs trained to locate them, there is no reason to use tongs during collection. The symmetric nature as well as the location of the markings discounts the source of them being dogs or other wild animals as can be seen in the photos of a female T. c. triunguis below. .     

Carapace pits in Terrapene carolina triunguis Carapace pits in Terrapene carolina triunguis (close-up)

Another theory is that this is a result of mating behavior,  the usual placement of the pitting corresponds closely with the placement of the front feet of males during mating. Males also will often mount other males during combat in the same manner. Keeping in mind that the keratin of a turtles shell is living tissue it requires no extraordinary leap of logic to reason that the shell after enduring small scratches in the seam between the scutes will over time develop small infections resulting in the pits, even on males as can be seen in the pictures below (both lateral views of the same male T. c. triunguis).

Carapace pits in male Terrapene carolina triunguis Carapace pits in male Terrapene carolina triunguis


The only problem in the above theory is that it does not explain why this pitting occurs almost exclusively in T. c. triunguis rather than all Terrapene,  who mate and engage in combat in the same manner.   It is the opinion of this author that mating and combat does have a partial responsibility for the pitting but that there is something else specific to the environment of T. c. triunguis that capitalizes on the scratching of the carapace resulting in the pits.


In any event, no treatment is required. The pits are natural. Their exact cause is unknown.




Carpenter, C.C. 1956. Carapace pits in the three-toed box turtle, Terrapene carolina triunguis (Chelonia-Emydidae). Southwest. Nat. 1:83-86. - World Chelonian Trust


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