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''Phrynosoma'', whose members are known as the horned lizards, horny toads, or horntoads, is a
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of North American
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 ...
s and the
type genus In biological taxonomy, the type genus (''genus typica'') is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearin ...
of the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Phrynosomatidae The Phrynosomatidae are a diverse family of lizards, sometimes classified as a subfamily (Phrynosomatinae), found from Panama to the extreme south of Canada. Many members of the group are adapted to life in hot, sandy deserts, although the spiny ...
. Their
common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...
s refer directly to their horns or to their flattened, rounded bodies (squat bodied), and blunt snouts. The generic name ''Phrynosoma'' means "toad-bodied". In common with true toads (
amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
s of the family
Bufonidae {{Cat main, Toad This category Category, plural categories, may refer to: General uses *Classification, the general act of allocating things to classes/categories Philosophy * Category of being * ''Categories'' (Aristotle) * Category (Kant) * C ...
), horned lizards tend to move sluggishly, often remain motionless, and rely on their remarkable camouflage to avoid detection by predators. They are adapted to arid or semiarid areas. The spines on the lizard's back and sides are modified
reptile scale Reptile skin is covered with scutes or Scale (anatomy), scales which, along with many other characteristics, distinguish reptiles from animals of other classes. They are made of Alpha-keratin, alpha and beta-keratin and are formed from the epiderm ...
s, which prevent water loss through the skin, whereas the horns on the head are true horns (i.e., they have a bony core). A
urinary bladder The bladder () is a hollow organ in humans and other vertebrates that stores urine from the Kidney (vertebrates), kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the ...
is absent. Of the 21 species of horned lizards, 15 are native to the USA. The largest-bodied and most widely distributed of the American species is the Texas horned lizard.


Defenses

Horned lizards use a variety of means to avoid
predation 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 List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
. Their coloration generally serves as
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
. When threatened, their first defense is to remain motionless to avoid detection. If approached too closely, they generally run in short bursts and stop abruptly to confuse the predator's visual acuity. If this fails, they puff up their bodies to cause them to appear more horned and larger so that they are more difficult to swallow. At least eight species (''P. asio'', ''P. cornutum'', ''P. coronatum'', ''P. ditmarsi'', ''P. hernandesi'', ''P. orbiculare'', ''P. solare'', and ''P. taurus'') are also able to squirt an aimed stream of blood from the corners of the eyes for a distance up to . They do this by restricting the blood flow leaving the head, thereby increasing blood pressure and rupturing tiny vessels around the
eyelid An eyelid ( ) is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. "Palpebral ...
s. The blood not only confuses predators but also tastes foul to canine and feline predators. It appears to have no effect against predatory
bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
s. Only three closely related species (''P. mcallii'', ''P. modestum'', and ''P. platyrhinos'') are certainly known to either be unable to squirt blood or only do it extremely rarely. While previous thought held that compounds were added to the blood from glands in the ocular sinus cavity, current research has shown that the chemical compounds that make up the defense are already in the circulating blood. It is possible that their diet of large quantities of venomous
harvester ant Harvester ant is a common name for any of the species or genera of ants that collect seeds (called seed predation), or mushrooms as in the case of '' Euprenolepis procera'', which are stored in the nest in communal chambers called granaries. T ...
s could be a factor; however, the origin and structure of the chemicals responsible are still unknown. The blood-squirting mechanism increases survival after contact with canine predators; the trait may provide an evolutionary advantage. Ocular autohemorrhaging has also been documented in other lizards, which suggests blood-squirting could have evolved from a less extreme defense in the ancestral branch of the genus. Recent phylogenic research supports this claim, so the species incapable of squirting blood apparently have lost the adaptation for reasons yet unstudied. To avoid being picked up by the head or neck, a horned lizard ducks or elevates its head and orients its cranial horns straight up, or back. If a predator tries to take it by the body, the lizard drives that side of its body down into the ground so the predator cannot easily get its lower jaw underneath.


Population decline

A
University of Texas The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas, United States. Founded in 1883, it is the flagship institution of the University of Texas System. With 53,082 students as of fall 2 ...
publication notes that horned lizard populations continue to disappear throughout their distribution despite protective legislation. Population declines are attributed to a number of factors, including the fragmentation and loss of habitat from real estate development and road construction, the planting of non-native grasses (both suburban and rural), conversion of native land to pastureland and agricultural uses, and pesticides. Additionally predation by domestic dogs and cats place continued pressure upon horned lizards. Fire ants ('' Solenopsis invicta''), introduced from South America via the nursery industry's potted plants, pose a significant threat to all wildlife including horned lizards. ''Phrynosoma'' species do not eat fire ants. Fire ants kill many species of wildlife, and are fierce competitors against the native ants, which horned lizards require for food (with their specialized nutritional content). Fire ants have given all ants a bad reputation, and human attempts to eradicate ants, including invasive species and the native species on which the lizards prey, contribute to the continued displacement of native ant species and the decline of horned lizards. The Texas horned lizard ('' Phrynosoma cornutum'') has disappeared from almost half of its geographic range. Their popularity in the early to mid-20th-century pet trade, where collectors took thousands from the wild populations to sell to pet distributors, without provision for their highly specialized nutritional needs (primarily formic acid from harvester ants), resulted in certain death for almost all the collected lizards. In 1967, the state of Texas passed protective legislation preventing the collection, exportation, and sale of ''Phrynosoma'', and by the early 1970s, most states enacted similar laws to protect and conserve horned lizards in the USA. As recently as the early 2000s, though, the state of
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 ...
still allowed commercial sale of ''Phrynosoma'' species. Despite limited federal protection in
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 ...
, horned lizards are still offered in Mexican "pet" markets throughout the country. In 2014, the
Center for Biological Diversity The Center for Biological Diversity is a nonprofit membership organization known for its work protecting endangered species through legal action, scientific petitions, creative media and grassroots activism. It was founded in 1989 by Kieran Suck ...
in Tucson petitioned the
Oklahoma Department of Wildlife Conservation The Oklahoma Department of Wildlife Conservation is an agency of the state of Oklahoma responsible for managing and protecting Oklahoma's wildlife population and their habitats. The Department is under the control of the Wildlife Conservation Co ...
to have the Texas horned lizard put on the endangered species list due to the massive decline of its population in Oklahoma, where it was once plentiful. The center said it may later seek protection for the animal on a federal level; it also said that reptiles in general are dying off at up to 10,000 times their historic extinction rate, greatly due to human influences.


Species and subspecies

The following 21 species (listed alphabetically by scientific name) are recognized as being valid by the
Reptile Database The Reptile Database is a scientific database that collects taxonomic information on all living reptile species (i.e. no fossil species such as dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared ...
, three species of which have recognized
subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
: ''Note'': In the above list, a binomial authority or trinomial authority in parentheses indicates that the species or subspecies was originally described in a genus other than ''Phrynosoma''.


Horned lizard (''Phrynosoma'') gallery

File:Coast Horned Lizard (9096387129).jpg, Blainville's horned lizard (''P. blainvillii)'' File:Phrynosoma braconnieri.jpg, Short-tailed horned lizard (''P. braconnieri)'', Oaxaca, Mexico (20 May 2013). File:Texas horned lizard (Phrynosoma cornutum), Armstrong County, Texas, USA (28 April 2013).jpg, Texas horned lizard (''P. cornutum''), Armstrong County, Texas, USA (28 April 2013) File:HORNED LIZARD, COAST (phrynosoma coronatum) (6-14-08) cerro alto north ridge, slo co, ca -01 (2579107136).jpg, Coast horned lizard (''P. coronatum''), San Luis Obispo County, California, USA (June 14, 2008) File:09-035 Horned Lizard (Phyrnosoma coronatum) (3481418737).jpg, Coast horned lizard (''P. coronatum'') (25 April 2009) File:Greater short-horned lizard on Seedskadee National Wildlife Refuge (27558656089).jpg, Greater short-horned lizard (''P. douglassi brevirostre''), Sweetwater County, Wyoming, USA (15 June 2016). File:Phrynosoma douglasii 4226.JPG, Pygmy short-horned lizard (''P. douglasii)'', Washington, USA (5 June 2014) File:Mountain short-horned lizard (Phrynosoma hernandesi), Culberson County, Texas, USA (19 May 2018).jpg, Mountain short-horned lizard (''P. hernandesi)'', Culberson County, Texas, USA (19 May 2018) File:Flat-Tailed Horned Lizard (5162160076).jpg, Flat-tailed horned lizard (''P. mcallii)'' (9 November 2010) File:Roundtail Horned Lizard (Phrynosoma modestum), Municipality of Tula, Tamaulipas, Mexico (15 August 2004).jpg, Round-tail horned lizard (''P. modestum''), Municipality of Tula, Tamaulipas, Mexico (15 August 2004) File:Mountain horned lizard (Phrynosoma orbiculare orientale), Municipality of Miquihuana, Tamaulipas, Mexico (24 September 2009).jpg, Mountain horned lizard (''P. orbiculare orientale''), Municipality of Miquihuana, Tamaulipas, Mexico (24 September 2009) File:Desert Horned Lizard in Mojave Desert.png, Desert horned lizard (''P. platyrhinos''), San Bernardino County, California, USA (9 July 2019) File:Horned lizard 032507 kdh.jpg, Regal horned lizard (''P. solare''), Apache Junction, Arizona, USA (25 March 2007)


Symbol

Texas designated the Texas horned lizard (''Phrynosoma cornutum'') as the official
state reptile Twenty-eight U.S. states have named an official state reptile. As with other United States state symbols, state symbols, states compare admirable aspects of the reptile and of the state, within designating statutes. Schoolchildren often start c ...
in 1993.Texas Horned Lizard
. State Symbols USA. Retrieved on 2016-10-25.
Wyoming’s state reptile is the “Horn Toad”, the greater short-horned lizard (''Phrynosoma hernandesi'').Mason Lee. 2022.
Wyoming’s surprising state reptile has spikes, shoots blood from eyes—
'. Barnyards & Backyards. 6-7 pp. University of Wyoming.
The " TCU Horned Frog" is the mascot of
Texas Christian University Texas Christian University (TCU) is a private university, private research university in Fort Worth, Texas, United States. It was established in 1873 by brothers Addison Clark, Addison and Randolph Clark as the AddRan Male & Female College. It i ...
in Fort Worth, Texas. The "Horned Toad" is also the mascot for Coalinga High School in Coalinga, California. This school is located in Western Central California and its arid region is home to the San Diego Horned Lizard, which is protected. The City of Coalinga hosts an annual "Horned Toad Derby" on Memorial day weekend which features horned toad races, a carnival and parade. File:Superfrog.jpg, The TCU mascot is commonly known as Super Frog to TCU fans and students. He is usually present at TCU sporting events. File:HornedToad.png, Horned lizard on a necktie at El Paso, Texas, in 1940


References


External links


Horned lizard skulls and info at Digimorph.org

Horned Lizard Conservation Society





Horned Toads - A field study of Short-horned Lizards by students of Waterville Elementary School
{{Taxonbar, from=Q288720 Phrynosoma Symbols of Wyoming Lizards of North America Taxa named by Arend Friedrich August Wiegmann