A living sponge
The thorny devil (Moloch horridus) is adapted for survival in the arid scrublands and deserts of central Australia. Growing up to 21 cm long, this lizard's most obvious feature is its intimidating covering of conical spines. These are for defense and they are part of a complex water-gathering system that allows the animal to thrive where water is scarce. The lizard's skin is covered in a network of microscopic, half-open channels and grooves that lie between its scales. The network acts like a sponge or blotting paper, drawing in any available moisture from the environment.
This water collection is a passive process driven by physics. When the lizard's skin comes into contact with water—from rain, dew-covered vegetation, or even just damp sand—capillary action wicks the fluid into the network of grooves. These channels are interconnected across the entire body and lead to the corners of the lizard's mouth. Water can travel against gravity, moving up the legs and across the torso to be drunk. The total water volume that the skin's capillary system can hold is about 3.19% of the lizard's body mass. Once the water reaches the mouth, the thorny devil makes small jaw movements to actively drink the collected fluid, consuming about 0.7 microliters per movement.