Horned lizard

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Horned lizard
Horned lizard 032507 kdh.jpg
Regal horned lizard
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Iguania
Family: Phrynosomatidae
Genus: Phrynosoma
Wiegmann, 1828
Type species
Lacerta orbiculare
Linnaeus, 1758

Phrynosoma, whose members are known as the horned lizards, horny toads, or horntoads, is a genus of North American lizards and the type genus of the family Phrynosomatidae. Their common names refer directly to their horns or to their flattened, rounded bodies, and blunt snouts.

Contents

The generic name Phrynosoma means "toad-bodied". In common with true toads (amphibians of the family Bufonidae), 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 scales, 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 is absent. [1] 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

Mexican Plateau horned lizard (Phrynosoma orbiculare) near Xalapa de Enriquez, Veracruz, Mexico, showing blood squirted from the eye as defensive behavior (20 April 2011) Phrynosoma orbiculare 1.jpg
Mexican Plateau horned lizard (Phrynosoma orbiculare) near Xalapa de Enríquez, Veracruz, Mexico, showing blood squirted from the eye as defensive behavior (20 April 2011)

Horned lizards use a variety of means to avoid predation. Their coloration generally serves as camouflage. 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. [2]

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 5 ft (1.5 m). [3] [4] [5] [6] They do this by restricting the blood flow leaving the head, thereby increasing blood pressure and rupturing tiny vessels around the eyelids. The blood not only confuses predators but also tastes foul to canine and feline predators. It appears to have no effect against predatory birds. 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. [4]

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. [4] [5] It is possible that their diet of large quantities of venomous harvester ants 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; [5] the trait may provide an evolutionary advantage. Ocular autohemorrhaging has also been documented in other lizards, [7] 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. [8]

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.[ citation needed ]

Population decline

Phrynosoma douglasii Phrynosoma douglasii 4220.JPG
Phrynosoma douglasii

A University of Texas 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. [9]

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. [9]

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 still allowed commercial sale of Phrynosoma species. Despite limited federal protection in Mexico, horned lizards are still offered in Mexican "pet" markets throughout the country. [9]

In 2014, the Center for Biological Diversity in Tucson petitioned the Oklahoma Department of Wildlife Conservation 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. [10]

Species and subspecies

The following 21 species (listed alphabetically by scientific name) are recognized as being valid by the Reptile Database, three species of which have recognized subspecies: [11]

ImageCommon NameScientific NameSubspeciesDistribution
Gfp-mexican-west-coast-giant-horned-lizard (crop 1).jpg Giant horned lizard Phrynosoma asio Cope, 1864southern Mexico
Baur's short-horned lizard Phrynosoma bauri Montanucci, 2015 (disputed; may be conspecific with P. hernandesi)United States ( southern Wyoming and Nebraska south through eastern Colorado to northern New Mexico)
Phrynosoma blainvillii 131129535.jpg San Diego horned lizard or Blainville's horned lizardPhrynosoma blainvillii Gray, 1839United States (southern and central California), Mexico (northern Baja California).
Phrynosoma braconnieri.jpg Short-tailed horned lizard Phrynosoma braconnieri A.H.A. Duméril, 1870Mexico (Puebla and Oaxaca)
Phrynosoma hernandesi - Flickr - aspidoscelis (11).jpg Great Plains short-horned lizard Phrynosoma brevirostris(Girard, 1858) (disputed; may be conspecific with P. hernandesi)Canada and the United States
Cedros Island horned lizard Phrynosoma cerroense Stejneger, 1893Mexico (Cedros Island)
Phrynosoma cornutum - Flickr - aspidoscelis (4).jpg Texas horned lizard Phrynosoma cornutum(Harlan, 1825)United States (southeast Colorado, central and southern areas of Kansas, central and western areas of Oklahoma and Texas, southeast New Mexico, and extreme southeast Arizona), Mexico (eastern Sonora, most of Chihuahua, northeast Durango, northern Zacatecas and San Luis Potosí, and throughout most of Coahuila, Nuevo León, and Tamaulipas.)
09-036 Horned Lizard (Phyrnosoma coronatum) (3481417849).jpg Coast horned lizard Phrynosoma coronatum (Blainville, 1835)
  • Cape horned lizard, P. c. coronatum(Blainville, 1835)
  • California horned lizard, P. c. frontale Van Denburgh, 1894
  • Central peninsular horned lizard, P. c. jamesi Schmidt, 1922
Mexico (Baja California Sur )
San Luis Valley short-horned lizard Phrynosoma diminutumMontanucci, 2015 (disputed; may be conspecific with P. hernandesi)United States (Colorado)
Ditmars' horned lizard or rock horned lizard Phrynosoma ditmarsiStejneger, 1906Mexico (Sonora), United States (Arizona)
Phrynosoma douglasii 4244.JPG Pygmy short-horned lizard Phrynosoma douglasii(Bell, 1828)northwestern United States and adjacent southwestern Canada
Sonoran horned lizard, Goode's desert horned lizardPhrynosoma goodeiStejneger, 1893United States (Arizona) and Mexico (Sonora)
Phrynosoma hernandesi - Flickr - aspidoscelis (11).jpg Greater short-horned lizard Phrynosoma hernandesiGirard, 1858southwestern United States and northwestern Mexico
Flat-Tailed Horned Lizard (5162160076).jpg Flat-tail horned lizard Phrynosoma mcallii(Hallowell, 1852)United States and Mexico
Phrynosoma modestum - Flickr - aspidoscelis (18).jpg Roundtail horned lizard Phrynosoma modestumGirard, 1852United States( Texas, New Mexico eastern Arizona, southeastern Colorado), northcentral Mexico
Lagarto Cornudo Camaleon Cornudo Iv (233411137).jpeg Mexican Plateau horned lizard or Chihuahua Desert horned lizardPhrynosoma orbiculare(Linnaeus, 1758)
  • P. o. bradti Horowitz, 1955
  • P. o. cortezii(A.H.A. Duméril & Bocourt, 1870)
  • P. o. dugesii(A.H.A. Duméril & Bocourt, 1870)
  • P. o. orbiculare(Linnaeus, 1758)
  • P. o. orientaleHorowitz, 1955
Mexico (Chihuahua, Durango, Morelos, Nuevo León, Puebla, and Veracruz.)
Desert short-horned lizard Phrynosoma ornatissimum(Girard, 1858) (disputed; may be conspecific with P. hernandesi)Canada and the United States
Desert Horned Lizard.jpg Desert horned lizard Phrynosoma platyrhinosGirard, 1852southern Idaho in the north to northern Mexico
Guerreran horned lizard Phrynosoma sherbrookei Nieto-Montes de Oca, Arenas-Moreno, Beltrán-Sánchez & Leaché, 2014Mexico.
Horned lizard 032507 kdh.jpg Regal horned lizard Phrynosoma solareGray, 1845Arizona and Mexico
Mexican horned lizard, Phrynosoma taurus.jpg Mexican horned lizard Phrynosoma taurus Dugès, 1873Mexico (Guerrero and Puebla)


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.

Comparison of P. modestum and P. platyrhinos Horned lizards.jpg
Comparison of P. modestum and P. platyrhinos

Symbol

Texas designated the Texas horned lizard (Phrynosoma cornutum) as the official state reptile in 1993. [12] Wyoming’s state reptile is the “Horn Toad”, the greater short-horned lizard (Phrynosoma hernandesi). [13] [14]

The "TCU Horned Frog" is the mascot of Texas Christian University 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.

Related Research Articles

<span class="mw-page-title-main">Greater short-horned lizard</span> Species of reptile

The greater short-horned lizard, also commonly known as the mountain short-horned lizard or Hernández's short-horned lizard, is a species of lizard in the family Phrynosomatidae. The species is endemic to western North America. Like other horned lizards, it is often called a "horned toad" or "horny toad", but it is not a toad at all. It is a reptile, not an amphibian. It is one of seven native species of lizards in Canada.

<span class="mw-page-title-main">Thorny devil</span> Species of lizard

The thorny devil, also known commonly as the mountain devil, thorny lizard, thorny dragon, and moloch, is a species of lizard in the family Agamidae. The species is endemic to Australia. It is the sole species in the genus Moloch. It grows up to 21 cm (8.3 in) in total length, with females generally larger than males.

<span class="mw-page-title-main">Anti-predator adaptation</span> Defensive feature of prey for selective advantage

Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avoiding detection, warding off attack, fighting back, or escaping when caught.

<span class="mw-page-title-main">Texas horned lizard</span> Species of lizard

The Texas horned lizard is one of about 21 North American species of spikey-bodied reptiles called horned lizards, all belonging the genus Phrynosoma. It occurs in south-central regions of the US and northeastern Mexico, as well as several isolated introduced records and populations from Southern United States. Though some populations are stable, severe population declines have occurred in many areas of Texas and Oklahoma. The Texas spiny lizard may be confused for a Texas horned lizard due to its appearance and overlapping habitat. Because the Texas horned lizard is listed as a threatened species in the state, it is illegal to pick up, touch, or possess them in Texas.

<span class="mw-page-title-main">Desert horned lizard</span> Species of lizard

The desert horned lizard is a species of phrynosomatid lizard native to western North America. They are often referred to as "horny toads", although they are not toads, but lizards.

Horned frog is a common name used to identify several kinds of frogs with hornlike features:

<span class="mw-page-title-main">Coast horned lizard</span> Species of lizard

The coast horned lizard is a species of phrynosomatid lizard endemic to Baja California Sur in Mexico. As a defense the lizard can shoot high pressure streams of blood out of its eyes if threatened.

The rock horned lizard, also known commonly as Ditmars' horned lizard and camaleón de roca in Mexican Spanish, is a species of lizard in the family Phrynosomatidae. The species is endemic to the Mexican state of Sonora, in northern Mexico, south of the Arizona border. Bearing the shortest horns of all the horned lizards, it lives in thorn-scrub and deciduous Sinaloan woodlands. The rock horned lizard was "lost" to science for about 65 years. It has a unique habitat preference and limited distribution. It also had a very imprecise holotype locality record which made it difficult to locate. An extraordinary effort by Vincent Roth based on a cross-correlational analysis of gut contents from only three specimens led to its rediscovery.

<span class="mw-page-title-main">Flat-tail horned lizard</span> Species of lizard

The flat-tail horned lizard is a species of lizard in the family Phrynosomatidae. A species of reptile, it is endemic to the Sonoran desert of the southwestern United States and northwestern Mexico. Its multiple adaptations for camouflage help to minimize its shadow. The species is threatened, with a restricted range under pressure from human activities such as agriculture and development, and is specially protected in the United States.

<span class="mw-page-title-main">Roundtail horned lizard</span> Species of lizard

The roundtail horned lizard is one of the smaller species of horned lizard. Their specific epithet is from the Latin word modestum, meaning modest or calm. They are found in the United States, in western Texas, New Mexico eastern Arizona, southeastern Colorado and eight states in northcentral Mexico where they are referred to as "tapayaxtin".

<span class="mw-page-title-main">Mexican Plateau horned lizard</span> Species of lizard

The Mexican Plateau horned lizard is a species of horned lizard in the family Phrynosomatidae. The species, also known commonly as the Chihuahua Desert horned lizard, is endemic to Mexico. There are five recognized subspecies. The specific epithet, orbiculare, comes from the Latin adjective orbis, meaning "circular".

The northern desert horned lizard is a subspecies of the desert horned lizard, along with the southern desert horned lizard. It is often referred to as a "horny toad" due to its wide body and blunt snout, but it is not a toad.

<span class="mw-page-title-main">Autohaemorrhaging</span> Action of animals deliberately ejecting blood from their bodies

Autohaemorrhaging, or reflex bleeding, is the action of animals deliberately ejecting blood from their bodies. Autohaemorrhaging has been observed as occurring in two variations. In the first form, blood is squirted toward a predator. The blood of these animals usually contains toxic compounds, making the behaviour an effective chemical defence mechanism. In the second form, blood is not squirted, but is slowly emitted from the animal's body. This form appears to serve a deterrent effect, and is used by animals whose blood does not seem to be toxic. Most animals that autohaemorrhage are insects, but some reptiles also display this behaviour.

<span class="mw-page-title-main">Mexican horned lizard</span> Species of lizard

The Mexican horned lizard is a horned lizard species native to Mexico. Horned lizards are sometimes referred to as "horned toads" or "horny toads", although they are not toads. Compared to other members of the horned lizards, little is known about this species.

<span class="mw-page-title-main">Regal horned lizard</span> Species of lizard

The regal horned lizard is a horned lizard species native to Mexico and the Southwest United States.

Skrjabinoptera phrynosoma is a parasitic worm in the phylum Nematoda, the most diverse of pseudocoelomates. Like many other parasites, the life cycle of S. phrynosoma is complicated and it involves two hosts – a lizard and an ant.

<span class="mw-page-title-main">Pygmy short-horned lizard</span> Species of lizard

The pygmy short-horned lizard is a species of small horned lizard in the family Phrynosomatidae. The species is native to the northwestern United States and adjacent southwestern Canada. Like other horned lizards, it is often called a "horned toad" or "horny toad," but it is not a toad at all. It is a reptile, not an amphibian.

<span class="mw-page-title-main">San Diego horned lizard</span> Species of phrynosomatid lizard

The San Diego horned lizard or Blainville's horned lizard is a species of phrynosomatid lizard native to southern and central California in the United States and northern Baja California in Mexico.

The Sonoran horned lizard, also known commonly as Goode's desert horned lizard and el camaleón de Sonora in Mexican Spanish, is a species of horned lizard in the family Phrynosomatidae. The species is native to Arizona in the United States and to Sonora in Mexico.

References

  1. ↑ Mader's Reptile and Amphibian Medicine and Surgery
  2. ↑ Winton, W. M. (1916-10-24). "Habits and Behavior of the Texas Horned Lizard, Phrynosoma cornutum, Harlan. I". Copeia. 36 (36). JSTOR: 81–84. doi:10.2307/1436504. ISSN   0045-8511. JSTOR   1436504.
  3. ↑ Middendorf III, G.A.; Sherbrooke, W.C.; Braun, E.J. (2001). "Comparison of Blood Squirted from the Circumorbital Sinus and Systemic Blood in a Horned Lizard, Phrynosoma cornutum". The Southwestern Naturalist. 46 (3): 384–387. doi:10.2307/3672440. JSTOR   3672440.
  4. 1 2 3 Sherbrooke, W.C.; Middendorf III, G.A. (2001). "Blood-Squirting Variability in Horned Lizards (Phrynosoma)" (PDF). Copeia. 2001 (4): 1114–1122. doi:10.1643/0045-8511(2001)001[1114:BSVIHL]2.0.CO;2. JSTOR   1448403. S2CID   86061329.
  5. 1 2 3 Sherbrooke, W.C.; Middendorf III, G.A. (2004). "Responses of Kit Foxes (Vulpes macrotis) to Antipredator Blood-Squirting and Blood of Texas Horned Lizards (Phrynosoma cornutum)". Copeia. 2004 (3): 652–658. doi:10.1643/CH-03-157R1. JSTOR   1448486. S2CID   55365586.
  6. ↑ Hodges, W.L. (2004). "Defensive blood squirting in Phrynosoma ditmarsi and a high rate of human-induced blood squirting in Phrynosoma asio". The Southwestern Naturalist. 49 (2): 267–270. doi:10.1894/0038-4909(2004)049<0267:DBSIPD>2.0.CO;2. JSTOR   3672697. S2CID   85923959.
  7. ↑ Sherbrooke, W. C. (2000). "Sceloporus jarrovii (Yarrow's spiny lizard) Ocular Sinus Bleeding". Herpetological Review. 31: 243.
  8. ↑ Leache, A. D.; J. A. McGuire (2006). "Phylogenetic relationships of hores lizards (Phrynosoma) based on nuclear and mitochondrial data: evidence for a misleading mitochondrial gene tree" (PDF). Molecular Phylogenetics and Evolution. 39 (3): 628–644. doi:10.1016/j.ympev.2005.12.016. PMID   16488160.
  9. 1 2 3 Pianka, Eric; Hodges, Wendy. "Horned Lizards, Part 2". uts.cc.utexas.edu. University of Texas. Archived from the original on April 26, 2015. Retrieved March 1, 2015.
  10. ↑ Godfrey, Ed (December 20, 2014). "Center for Biological Diversity wants Texas horned lizard declared an endangered species in Oklahoma". The Daily Oklahoman . Retrieved November 5, 2018.
  11. ↑ Genus Phrynosoma at The Reptile Database www.reptile-database.org.
  12. ↑ Texas Horned Lizard Archived 2015-04-01 at the Wayback Machine . State Symbols USA. Retrieved on 2016-10-25.
  13. ↑ "State symbols". Wyoming Secretary of State's Office. 2011. Archived from the original on September 6, 2011. Retrieved January 22, 2011.
  14. ↑ Mason Lee. 2022. Wyoming’s surprising state reptile has spikes, shoots blood from eyes— . Barnyards & Backyards. 6-7 pp. University of Wyoming.
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