The abundance and diversity of life is greatest where water is plentiful. But some species manage to thrive in dry, inhospitable habitats around the globe. By developing novel methods for acquiring water and effective ways to conserve it, animals such as sand lizards are able to exploit less competitive habitats.
Sand Lizard Description
"Sand lizard” usually refers to the European lizard (Lacerta agilis). Native to dry, sandy habitats, sand lizards are small reptiles who reach almost 10 inches in length. Sexually dimorphic, males are bright green, while the females and juveniles are predominately brown. Sand lizards have long life spans; taking two to three years to mature, they have average life expectancy of more than a decade. Sand lizards primarily hunt large insects and other invertebrates.
Sand Lizard Habitat
Mediterranean scrubland -- characterized by dense clusters of vegetation separated by stretches of sand and exposed dirt -- is the preferred habitat of sand lizards. These open areas with well-drained substrates are crucial to the lizards’ survival. Each spring, adult female sand lizards dig small burrows for their eggs. Because the sites are open and exposed to the sun, the eggs remain warm enough to develop and ultimately hatch. Winters are cold in some parts of the sand lizard territory, and the lizards must hibernate in rock crevices, tree stumps or similar sheltered locations.
The water acquisition methods of sand lizards have not been the subject of great study, but it is likely that they engage in similar behaviors to those seen in other sand-dwelling lizards. Mediterranean scrub habitats are not completely xeric, and occasionally sand lizards will therefore encounter and drink from small puddles. They're small lizards, so a few droplets of water can fill their stomachs; droplets of water from rain or dew may provide life-sustaining levels of water. Though the behavior hasn't been noted in sand lizards, many desert lizards adopt body postures that channel small amounts of rain or condensed water into their mouths. Additionally, the insects that sand lizards eat contain a small amount of water.
Acquiring water is only part of the problem for animals living in dry habitats. They must retain as much water as possible for as long as possible. Sand lizards do so by reabsorbing most of the water in their urine and retreating to damp refuges during the heat of the day to slow the rate of evaporation.
Other Desert Lizards
In addition to the European sand lizard, several species around the world sometimes bear the name sand lizard. While their specific biology and evolutionary history may differ, all lizards inhabiting deserts or dry habitats must cope with the lack of environmental moisture. Most species do so in the same ways that the European lizards do -- by opportunistically drinking water droplets, conserving water found in food, removing water from their urine and using damp retreats to retard evaporation. Additionally, though not a tactic of the insectivorous Lacerta agilis, some desert-dwelling lizards acquire all of their necessary moisture by eating plants.