The desert horned lizard (''Phrynosoma platyrhinos'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of phrynosomatid

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

native to western

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. They are often referred to as "horny toads", although they are not

toad Toad (also known as a hoptoad) is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands. In popular culture (folk taxonomy ...

s, but lizards.

Description

There are several important characteristics that can be used to identify desert horned lizards from other horned lizards. Horned lizards can be distinguished from other lizards by the large pointed scales that protrude from the back of their heads, giving them the appearance of having horns, as well as the flat and broad shape of their bodies. This species of lizard has a distinctive flat body with one row of fringe scales down the sides. They are a medium sized lizard and can grow up to approximately 3.75 inches or 95mm in size. They have one row of slightly enlarged scales on each side of the throat. Colours can vary and generally blend in with the color of the surrounding

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

, but they usually have a beige, tan, or reddish dorsum with contrasting, wavy blotches of darker color. They have two dark blotches on the neck that are very prominent and are bordered posteriorly by a light white or grey color. They also have scattered pointed scales and other irregular dark blotches along the dorsum of their body. Unlike other horned lizards, ''Phrynosoma platyrhinos'' individuals do not have a prominent dorsal stripe. Their dorsal stripe can appear faintly or be entirely absent depending on the individual. They also have pointed

scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number ...

on the dorsum (back) of the body. Juveniles are similar to adults, but have shorter and less-pronounced cranial spines. Desert horned lizards have horns that are wide at the base, which isn't true for their congener, the short-horned lizard. Pictured to the left is Blainville's Horned Lizard (Phrynosoma blainvillii), note the colored horns and double row of fringed scales alongside the body. The desert horned lizards' horns also do not come into contact with one another at the base.

Diet

Desert horned lizards

prey Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...

primarily on

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

s, such as ants (including red harvester ants,) crickets, grasshoppers, beetles, worms, flies, ladybugs, meal worms and some plant material. They can often be found in the vicinity of ant hills, where they sit and wait for

ants Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...

to pass by. Ants contain a large amount of chitin, an indigestible compound, this makes them not as nutrient rich, so larger amounts must be consumed to sustain ''Phrynosoma platyrhinos.'' As an evolutionary advantage desert horned lizards developed larger stomachs to allow them to consume larger concentrations of ants. When they find an area of soft sand, they usually shake themselves vigorously, throwing sand over their backs and leaving only their head exposed. This allows them to hide from predators and await their unsuspecting prey.

Habitat

Found in extremely diverse habitats. The flat-tailed horned lizard occurs in areas of fine sand, while the short-horned lizard (''P. douglasii'') is found in shortgrass prairie all the way up into spruce-fir forest. The most common species in the Arizona Upland subdivision is the regal horned lizard (''P. solare''), which frequents rocky or gravelly habitats of arid to semiarid plains, hills and lower mountain slopes. The desert horned lizard (P. ''platyrhinos'') is found mostly in the Sonoran and Mojave deserts. It can be found in southeastern Oregon, California, western Arizona Utah, Idaho and Nevada. Outside of the United States it is found in Mexico, northwestern Sonora, and northeastern Baja California. They have a preference for places that they can find shrub covering with an understory. ''Phrynosoma platyrhinos'' will often bury themselves in sand soil, if possible, or they will live in burrows that were constructed by other animals.

Geographic range and subspecies

They typically range from southern

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

in the north to northern

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

in the south. These lizards can generally be found in areas with desert climates throughout western North America. Changes in the environment due to climate change can trigger shifts in the geographic ranges of animals. ''Phrynosoma platyrhinos'' has experienced some changes after the Last Glacial Maximum (LGM) which ended approximately 21,000 years ago. The end of the LGM resulted in the expansion of deserts throughout western North America, and with that expansion ''Phrynsoma platyrhinos'' had more areas suitable for them to live in. At the end of the LGM P. ''platyrhinos'' was able to expand north into the Great Basin, which is now part of their current geographical range. There are two subspecies which are found in a different geographic ranges: the northern desert horned lizard ('' Phrynosoma platyrhinos platyrhinos'') ranging in

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

, the Colorado front range, and parts of southeastern

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

; and the southern desert horned lizard (''Phrynosoma platyrhinos calidiarum'') ranging in southern

and

to southeast

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

, western

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

, and northern

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

Behavior

They are generally a gentle species, but have been known to try to push their cranial spines into the hand while held. When excited, they puff themselves up with air, similar to the way a Chuckwalla does, making themselves look bigger. If spotted near a bush, they will dash into it in an attempt to find cover from any threat. Unlike most other species of horned lizard, ''Phrynosoma platyrhinos'' is most likely to run when startled, though they will often only run for a short period of time before stopping again. Unlike several other horned lizard species, desert horned lizards almost never squirt blood from their eyes. The desert horned lizard has also been observed to exhibit rain-harvesting behavior in the wild, a behavior previously only attributed to a handful of other species. When rain-harvesting the lizard adopts specific posture in order to get its mouth closer to the ground. Like other iguanids P. ''platyrhinos'' performs a number of displays. Iguanid displays are usually used to assert a social structure or for aggression and courtship, and can present in a variety of different behaviors such as: push ups, bobbing of the head, tail movements, along with changes in posture. In P. ''platyrhinos'' these displays are less aggressive and appear to be most concerned with sex and species recognition. These behaviors include various tail positions such as curled, between the legs, or arched down with scratching behaviors, push ups, and a three-legged stance where one of the hind legs is held off the ground and the back is presented to predators.

Description

Diet

Habitat

Geographic range and subspecies

Behavior

See also

References

Further reading