Tree frogs don't drink water through their mouths. Instead, they absorb moisture through a 'drinking patch' on their bellies.

Most amphibians utilize a specialized area of skin on their lower abdomen known as the 'pelvic patch' or 'drinking patch' for hydration. This region is uniquely adapted with a high density of aquaporins, which are membrane proteins that facilitate the flow of water molecules. Research published in journals like 'Nature' and 'Journal of Experimental Biology' highlights that this patch can account for up to 70% of a frog's total water intake.The process works through osmosis, where water moves from an area of high concentration on a wet leaf to a lower concentration inside the frog's body. Because tree frogs live in arboreal environments where standing water is scarce, they rely on dew and rain trapped on foliage. This evolutionary trait allows them to survive high above the ground without descending to ponds or streams frequently.However, this permeable skin is a double-edged sword. Since the skin lacks a thick waterproof layer like keratin, it also absorbs chemicals, pesticides, and heavy metals from the environment. Scientists often use tree frogs as 'bioindicators' because their health directly reflects the purity of the local ecosystem. Studies by institutions like the Smithsonian Tropical Research Institute have shown that even trace amounts of pollutants can disrupt their endocrine systems through this abdominal absorption.