Green tree frogs do not drink water with their mouths like mammals. Instead, they hydrate by absorbing water directly through their skin-a process known as cutaneous absorption.
Specialized Skin Regions
-
Pelvic Patch (Seat Patch):
Green tree frogs, like many other amphibians, have a specialized area of skin on the underside of their bodies called the pelvic patch or seat patch. This region, which extends across the lower abdomen and hindlimbs, is especially adapted for rapid water uptake from moist surfaces or shallow water.
-
Skin Structure:
The skin in these regions contains a dense network of capillaries and specialized cells, making it highly permeable to water. The presence of aquaporin proteins (water channels) in the skin cells further facilitates efficient water movement into the body.
How Water Absorption Works
-
Direct Absorption:
When a green tree frog sits on a wet surface, water moves from the environment into the frog’s body through the skin by osmosis. This is driven by the difference in water concentration between the moist environment and the frog’s internal tissues. -
Condensation Collection:
During dry periods, green tree frogs have been observed sitting outside on cool nights. When they return to their warmer dens, condensation forms on their skin-much like fog on cold glass. The frogs then absorb this condensed moisture through their skin, helping them stay hydrated even when free water is scarce. -
Efficiency:
Studies have shown that green tree frogs can absorb up to 60% of each water drop that lands on their skin, making this method highly effective for hydration, especially in arid environments.
Additional Adaptations
-
Mucus Secretion:
Their skin secretes a thin layer of mucus, which not only helps retain moisture but also aids in the absorption process and provides antibacterial and antiviral protection.