Xantusiidae – Night lizards

A family of small, secretive lizards found predominantly in the southwestern United States, Mexico, and Central America, including several islands off the Pacific coast.

One of the most interesting characteristics of night lizards is their size and appearance. Typically, they measure only about 4 to 15 cm (2 to 6 in) in length, with a flattened body that helps them squeeze into tight spaces between rocks, under bark, or within crevices. Their skin usually exhibits colors and patterns that mimic their surroundings—browns, grays, and greens—which provide excellent camouflage against predators. This camouflage is crucial for survival, as they tend to freeze rather than flee when threatened.

Night lizards have several unique adaptations that suit their relatively sedentary lifestyle. For one, they are viviparous, meaning they give birth to live young rather than laying eggs. This is rare among lizards and provides an advantage in their often harsh and unpredictable environments, as it eliminates the need to protect eggs from temperature fluctuations and predation. Typically, a female night lizard will give birth to one to three offspring, which are relatively large compared to the mother’s size.

The diet of night lizards primarily consists of small insects and arthropods, such as ants, beetles, and spiders. They use a sit-and-wait strategy, staying almost motionless and waiting for prey to come within striking distance before capturing it with quick movements. This low-energy approach to feeding aligns with their overall energy-efficient lifestyle, which is necessary given the limited resources available in their often arid habitats.

Night lizards have an unusually long lifespan for their size. Some species can live for more than a decade, which is remarkable for such small reptiles. Additionally, night lizards exhibit a high degree of territoriality and can occupy the same crevice or rock pile for many years, rarely venturing far from their home base.