I am sure many of you have other herps and have already found poops from snakes or monitor lizards in their water dishes!
It's not only a matter of being inside water. Human constipation was formerly treated by WARM baths instead of our modern laxatives. Personal theory: the reduced gravity in water PLUS the heat has a mechanical action on any land-based vertebrate's digestive tract. The metabolism is stimulated by heat, including the intestines, which work faster. There is also a small amount of water likely to go inside the rectum (or cloaca for reptiles) which then triggers defecation, as stools are first stored inside such "natural chambers" before being eliminated.
My Uroplatus all drink from water dishes to, by the way. My
lineatus tend to do it even more than the other species I keep.
As for the "vent soaking" debate, I once had a dehydrated
henkeli male. Before talking about rehydrating him
per os with electrolyte solutions, my vet recommended that I give 1-2 baths a day to this animal with lukewarm water and insisted on the role of the vent part as having a high water absorption capacity.
Considering the anatomy of reptiles, this really makes sense: the cloaca is in contact with the colon, or low intestine; the sole purpose of the colon on vertebrates is to absorb water, the small intestine does all the digestion/nutrient assimilation job prior to sending fecal maters into the colon. The colon mainly absorbs water, and you can live without one. But then, you have to be hydrated by artificial means. The inside of the cloaca and the terminal part of the intestine are particularly rich in nervous cells, of specialized ciliated cells which push the feces down to the cloacal opening, and of other specialized cells able to absorb a huge amount of water compared to their size. In humans, the rectum is like a cavity able to enlarge considerably, thanks to these cells which absorb the remains of water so as to make the feces solid- when you suffer from diarrhea, the digestive tract is working too fast and thus it doesn't leave enough time for the colon and rectum to retain most of the water in feces, that's the reason why diarrheas are semi-liquid. I know enough about human enterology and proctology to be sure of what I am saying, and this applies to reptiles as well, as the cellular structure of the lower intestine is pretty similar in most vertebrates. Only its length may differ according to the diets of each species.
Hope that helps answering the observations made by several Uro keepers here. When you see your uros inside their water dish, and this is clearly shown in photos posted on this thread, they instinctively put their vent inside the water
