Stance and Skin Channels Harvest Rainwater

close up of a tan lizard with black spots and little horns against a blurry tan background

Biological Strategy

Texas horned lizard

AskNature Team

Image: Vincent Parsons / Flickr / CC BY - Creative Commons Attribution alone

Capture, Absorb, or Filter Liquids

The most common liquid used by living systems is water, which they require to survive. But there are many other liquids that provide nourishment, play a role in defense mechanisms, or serve other purposes. Water varies in its availability; it is sometimes plentiful and sometimes very scarce or only available as fog or mist. To minimize the energy required to capture, absorb, or filter liquids, living systems have strategies that take advantage of the unique properties of the given liquid. For example, water moves from a gaseous to liquid state when it encounters a surface colder than the air. Plants in forests that experience fog and clouds more than rain have strategies that condense liquid water from moist air.

Search this Function

Reptiles

Class Reptilia (“creeping”): Lizards, crocodiles, turtles, snakes

Reptiles retain some of the key characteristics that first enabled vertebrates to live permanently on land. They have dry skin covered in scales made of keratin that help prevent water loss. (Amphibians still need to stick close to water to keep their skin moist.) Many reptiles reproduce by laying eggs that are watertight and have a yolk, so eggs can develop on land while staying moist and nourished. Reptiles are also ectotherms, meaning they don’t produce their own body heat. This means they burn through energy much more slowly than “warm blooded” creatures of the same size. It also means that they need to keep warm to keep active, which is why you might see them spending a seemingly inordinate amount of time simply basking in the sun.

Search this Living System

The body of Texas horned lizards captures rainwater via splayed stance and interscalar channels on the skin.

“During rainstorms, Texas horned lizards in enclosures were observed to exhibit a stereotyped behavior termed ‘rain-harvesting.’ The behavior involves: (1) raising the abdomen in an arch; (2) splaying and extending the legs; (3) dorso-ventral flattening and lateral spreading of the body; (4) lowering the head and tail; (5) opening and closing the jaws; and (6) drinking water collected on the dorsal body surface. Ingestion of integumentally-derived water was verified by recovery of dyed water from the gut. SEM stereophotographs illustrate the interscalar channels through which water is carried, apparently by , over body surfaces to the jaws. During light rainfall water flow to the jaws occurs within interscalar channels, but during heavy rainfall gravitational sheet flow may increase the amount of water arriving at the jaws. This integumental rain-harvesting system is similar to reported interscalar water transport in two agamid lizards, Moloch horridus and Phrynocephalus helioscopus. Apparently, Phrynosoma and P. helioscopus have similar behaviors for rain-harvesting. This is the first report to provide observations of a lizard obtaining water from natural precipitation for drinking by integumental interception and transport.” (Sherbrooke 1990:302)

Last Updated September 14, 2016

References

Journal article

Rain-Harvesting in the Lizard, Phrynosoma cornutum: Behavior and Integumental Morphology

Journal of Herpetology | 05/05/2006 | Wade C. Sherbrooke

embedly preview

Reference

Journal article

Integumental water movement and rate of water ingestion during rain harvesting in the Texas horned lizard, Phrynosoma cornutum

Amphibia-Reptilia | 14/04/2004 | Wade Sherbrooke

embedly preview

AskNature