Observation about substrate swallowing

I thought others might be interested in this. I keep my Salamandra salamandra terrestris and S. s. gallaica juveniles on unbleached white paper towelling. Here and there I put bits of old rotting moss which is very fragmented. The animals hide under this or in two upside-down plastic flower port dishes that have had a piece cut out of them to make a door.

Anyway, Salamandra are reasonably active hunters, even going so far as to charge at food if it's moving away from them. They're rather indescriminate with their tongue flicks, and frequently they end up getting fragments of moss rather than the food item. They seem to spit the fragments out, but yesterday I examined the fecal pellets of 4 or 5 of the animals, and I was quite surprised to find a large number of moss fragments in each one. I don't think this does them any harm (under these conditions my S. s. terrestris have grown from 5 cm in late June to 9 cm now), but it was quite alarming. Needless to say, I'm not in a hurry to keep them on small-sized gravel...

When my fire sals eat, they always thrash their food around, wiping it across whatever substrate they happen to be standing on. I suspect that, in nature, salamanders probably injest all sorts of junk along with their food. Who knows, maybe the "roughage" is good for their digestion (or, more likely, it probably has no effect). I agree that I wouldn't want them eating gravel.