Horned Lizard

Quick Take

• Horned lizards have a defense mechanism so bizarre it sounds like fiction, and it comes from the last place you'd expect. See the bizarre defense →
• Not all horned lizards reproduce the same way, and one species breaks the reptile rulebook entirely. Explore reproductive strategies →
• The biggest threat to horned lizards is not their predators. It is something humans use to kill something much smaller. Discover the human threat →
• Their hunting technique relies on a strategy most predators would never attempt. See their hunting technique →

They look like a cross between a dinosaur and a toad with their flat, froggy bodies and crown of horns — but horned lizards are reptiles. These lazy lizards need every adaptation they can get — horns, sharp scales, eyes that shoot blood, and excellent camouflage — to live among a host of the desert’s most deadly predators.

There are 21 recognized species of horned lizards throughout North and Central America, often mistaken for toads because of their wide, flat bodies and stubby tails. Like all lizards, the males are known to vigorously bob their heads and do “push-ups” to attract females during mating season. Unlike other lizards, the horned lizard can defend itself by squirting blood from its eyes.

5 Interesting Horned Lizard Facts

• There are 21 species of horned lizards in the world. These include the Texas horned lizard, short-horned lizard, and mountain horned lizard.
• These lizards have horn-like structures all over their bodies, especially around their head.
• Horned lizards blend into the landscape, which is one of their adaptations to conceal them from predators.
• They are known to live in a variety of habitats — from deserts to dense forests. They require a semi-arid environment to thrive.
• Most horned lizards live at least five years.

Evolution

The earliest reptiles, such as Hylonomus, first appeared during the Carboniferous Period around 312 million years ago, though the major reptile lineages diversified from one another over a broader span of time. There are lizards all over the world that have adapted to habitats that are as varied as the thousands of species within this family.

Classification and Scientific Name

Horned lizards are classified in the genus Phrynosoma. They are members of the Phrynosomatidae family in the order Squamata. The literal translation of “Phrynosoma” is “toad-bodied,” referring to their wide midsection.

Species

There are 21 species of horned lizard, including:

• Giant horned lizard (Phrynosoma asio): endemic to the Pacific coast of southern Mexico, this lizard is the largest of the different species and is the only one that is shaped like a typical lizard.
• Baur’s short-horned lizard (Phrynosoma bauri): can be found all over the United States.
• Coast horned lizard (Phrynosoma blainvillii): also called Blainville’s horned lizard, this species is native to southern and central California in the U.S. and northern Baja California in Mexico.
• Short-tailed horned lizard (Phrynosoma bracconnieri): endemic to Mexico, this species has a shortened tail which is not always visible.
• The Great Plains short-horned lizard (Phrynosoma brevirostris): native to Canada and the United States.
• Cedros Island horned lizard (Phrynosoma cerroense): can only be found on Cedros Island in Mexico.
• Texas horned lizard (Phrynosoma cornutum): can be found in south-central regions of the U.S. and northeastern Mexico as well as some isolated populations in the southern United States.
• Coast horned lizard (Phrynosoma coronatum): endemic to Baja California Sur in Mexico, this species can shoot high-pressure streams of blood out of its eyes when threatened.
• Pygmy short-horned lizard (Phrynosoma douglasii): often called a “horny toad,” this species is native to the northwestern United States and adjacent southwestern Canada.
• Rock horned or Ditmars’ horned lizard (Phrynosoma ditmarsi): endemic to the Mexican state of Sonora. It has the shortest horns of all of the species and only lives in thorn-scrub and deciduous Sinaloan woodlands.

Appearance

There are 21 species of horned lizard, and while each has its specific features, the one thing that remains common in all of them is the armor of horns. These toad-shaped lizards, as the name suggests, are covered in horn-like scales that make them appear unpalatable to predators. The largest of the horns usually rests on their heads — while two of them are on their brows, and many protrude from their jawline, going up to the skull’s temporal portion. Two rows of horns or spikes run along the lateral portions of their torso and separate the larger spikes on their dorsal side from their scaly underbelly.

The species vary in size; the snout-vent length of the female Texas horned lizard, for instance, measures about 5 inches, while the male’s is only around 3 inches. Female horned lizards are usually larger than males.

Behavior

Horned lizards are solitary creatures and are normally active between 60 and 80 degrees Fahrenheit, which is why they thrive in so many environments across North America and Central America. During summers or otherwise hot days, they are mostly active during the morning hours and become less active during the afternoon. They usually prefer soft, sandy soils near rocks. This allows them to blend smoothly into the landscape and avoid catching the eyes of their many predators.

The Texas horned lizard, for example, can be found lying on open ground during mornings and evenings. They tend to bask in the sun while hunting for insects — ants being their favorite food.

Some horned lizards hibernate from October through late March. Soon after horned lizards come out of hibernation, mating season begins. Male lizards attract females by bobbing their heads and doing push-ups to signal readiness for mating.

Habitat

Horned lizards are found in the Sonoran Desert region. They are found throughout the area from near sea level up to 11,300 feet (3,340 meters). Some of the species of these lizards, like the round-tailed lizard and the Texas horned lizard, occur in several US and Mexican states.

Meanwhile, the flat-tailed horned lizard is restricted to Southwestern Arizona, Southeastern California, and a small part of northeastern Baja California. They are also found in the upper neck of the northwestern Sonora region in Mexico, though they can live as far south as Guatemala.

Studies suggest that most horned lizards live in semi-arid environments and deserts, where they can often be seen basking in the sun during summer days. They can also be found in less typical habitats — from areas of fine sand to dense forests.

Diet

While the diet of specific species varies, most horned lizards feed on various types of ants as well as insects. The short-horned lizard, for example, mainly feeds on harvester ants.

Apart from that, they also eat beetles and spiders, but they will occasionally ingest small pebbles. To trap their unsuspecting prey, the Texas Horned lizards lie motionless while ants walk across them. Then, they leap out and capture the ants as soon as they touch the ground.

Predators and Threats

Horned lizards face threats from a lot of predators, including dogs, wolves, hawks, snakes, and roadrunners. However, hungry animals are not the only things that pose a threat to these lizards. Because ants make up most of their diet, the pesticides that are used on ants also end up harming horned lizards.

Other threats include invasive red fire ants, illegal pet trade, climate change, and drought, all of which can impact the habitat and lifestyle of these lizards.

Reproduction and Life Cycle

Different types of horned lizards mate in different ways. In the case of the Texas horned lizards, mating usually happens in April and May, and the eggs are laid in May or June. The female digs a slanting tunnel that is about six inches long. She lays about 27 eggs and places them in three horizontal layers that are separated by firm layers of sand. The cream-colored eggs are very tough and leathery and hatch in about 40 days.

The round-tailed horned lizard, however, follows a different process. While it also lays eggs, it retains them inside its body until the embryos develop. The eggs are membranous, and the hatchlings emerge as soon as the eggs are deposited.

the short-horned lizard, however, is the only type that gives birth to live young and does not lay eggs. The young remain inside the mother until they are ready to be born.

While little information is available about the lifespan of horned lizards, they are known to live at least five years.

Population

While the exact population of these lizards is not known, they appear to be robust in number. However, their population is declining because their diet mainly includes ants, and the pesticides that kill the ants also tend to harm horned lizards. In addition, human activities such as urbanization and the pet trade have also affected horned lizard populations.