Iguana (/ɪˈɡwɑːnə/,[1][2] Spanish: [iˈɣwana]) is a genus of herbivorous lizards that are native to tropical areas of Mexico, Central America, South America, and the Caribbean. The genus was first described in 1768 by Austrian naturalist Josephus Nicolaus Laurenti in his book Specimen Medicum, Exhibens Synopsin Reptilium Emendatam cum Experimentis circa Venena. Two species are included in the genus Iguana: the green iguana, which is widespread throughout its range and a popular pet, and the Lesser Antillean iguana, which is native to the Lesser Antilles and endangered due to habitat destruction, introduced feral predators, hunting, and hybridization with introduced green iguanas.

The word "iguana" is derived from the original Taino name for the species, iwana.[3]

In addition to the two species in the genus Iguana, several other related genera in the same family have common names of the species including the word "iguana".

Portrait of an Iguana
A green iguana (Iguana iguana)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Iguania
Family: Iguanidae
Genus: Iguana
Laurenti, 1768
  • Hypsilophus Wagler, 1830

Anatomy and physiology

Iguanas can range from 1.5 to 1.8 metres (5 to 6 ft) in length, including their tail. The two species of lizard within the genus Iguana possess a dewlap and a row of elongated scales running from the midline of their necks down to their tails. Iguanas have varying types of scales covering different areas of their body, for example, there are some large round tuberculate scales scattered around the lateral region of the neck among smaller, overlapping scales.[4] The scales on the dorsal trunk of their body are also thicker and more tightly packed than those on the ventral side.[4] These scales may be a variety of colors and are not always visible from close distances. They have a large round scale on their cheeks known as a sub-tympanic shield.[5]

Iguanas have keen vision and can see shapes, shadows, colors, and movement at long distances. Their visual acuity enables them to navigate through crowded forests and to locate food. They employ visual signals to communicate with other members of the same species.[5]

The tympanum, the iguana's eardrum, is located above the sub-tympanic shield (or "ear shield") behind each eye. Iguanas are often hard to spot, as they tend to blend into their surroundings and their coloration enables them to hide from larger predators.[5]

Like most reptiles, an iguana has a three-chambered heart with two atria, one ventricle, and two aortae with a systemic circulation.[6]

Iguana Dorsal Muscles Labeled
The dorsal view of the muscles of an adolescent iguana

The muscles of an iguana are very light in color, this is due to the high proportion of fast glycolytic muscle fibers. These fibers are not very vascularized and are low in myoglobin, giving them their pale look. This high density of fast glycolytic muscle fibers allows iguanas to move very quickly for a short period of time, which facilitates short bursts of movement but is inefficient for long duration movement, since cellular respiration in fast glycolytic muscle fibers is anaerobic.

Adult Iguana parietal eye
The parietal eye of an adult iguana circled in red

Parietal eye

Several species of lizard, including the iguana, have a pale scale towards the back of their head marking the parietal eye. This organ is photosensitive to changes in illumination and sends signals to the pineal gland signaling the change between day and night. A photopigment commonly found in the lamprey, known as parapinopsin, is also found in the iguana and is photosensitive to UV light and aids in the signaling between day and night.[7]

Skull morphology and diet

Iguana iguana eating Mangifera indica from Venezuela
Iguanas have an exclusively herbivorous diet,[8] as illustrated above by a green iguana eating a mango in Venezuela

Iguanas have developed a herbivorous lifestyle, foraging exclusively on vegetation and foliage.[8] In order to acquire, process and digest plant matter, herbivorous lizards must have a higher bite force relative to their size in comparison to carnivorous or omnivorous reptiles. The skull of the iguana has undergone modifications resulting in a strong bite force and efficient processing of vegetation, according to one study.[9]

In order to accomplish this biomechanically, herbivorous lizards (such as the iguana) have taller and wider skulls, shorter snouts, and larger bodies relative to carnivorous and omnivorous reptiles.[9] Increasing the robusticity of the skull allows for increased muscle presence and increases the ability of the skull to withstand stronger forces.[10]

Green Iguana skull (Iguana iguana) and teeth
Green iguana skull and teeth. The teeth of the green iguana sit on the surface of the jawbone, known as acrodontal placement.[11]

Furthermore, the teeth of the iguana are acrodontal, meaning that their teeth sit on top of the surface of the jaw bone[11] and project upwards. The teeth themselves are small and serrated - designed to grasp and shear food.[12]


Iguana ovaries
The early developed ovaries of an adolescent iguana are shaded in red

Male iguanas, like other male examples of Squamata, have two hemipenes. During copulation one hemipene will be inserted into the female's cloacal vent. Females can store sperm from previous mates for several years to continue to fertilize her eggs in case she finds no male within her territory when she is ready to lay again.


Iguanas tend to follow a promiscuous or polygynadrous mating style during the dry season. Mating during the dry season ensures that their offspring will hatch during the wet or rainy season when food will be more plentiful. Females control large territories where they make several nests. Males compete amongst each other for the females in an area and mark their won territory with a pheromone secreted from the femoral pores on the dorsal side of their hind limbs. Male behavior during sexual competition involves head bobbing, extending and retracting their dewlap, nuzzling and biting the necks of females, and on occasion, changing color. Once a female chooses a male, he will straddle the female and hold her in place by biting onto her shoulder, which sometimes leaves scars on females. After copulation, eggs are laid within several nests and allowed to incubate. This low level of parental intervention with their offspring makes iguanas an example of r-strategy reproduction.


A phylogeny based on nuclear protein-coding genes, reviewed by Vidal and Hedges (2009) suggested that the subclade Iguania is in a group with snakes and anguimorphs (lizards). These groups share an oral gland capable of secreting toxins (a derived trait).[13] On the other hand, the phylogeny based on whole mitochondrial genomes, proposed by Rest et. al. (2003), places the green iguana as the closest relative of the mole skink (Plestiodon egregius). [14] Lepidosaurs are reptiles with overlapping scales, and within this group both iguanians and tuataras (Sphenodons) project their tongue to seize prey items instead of using their jaw, which is called tongue prehension. However, iguanians are the only lineage within Squamata that displays this trait, meaning that it was gained independently in both iguanians and tuataras. [13] Iguanians are also the only squamates that primarily use their sight to identify and track prey rather than chemoreception or scent, and employ an ambush technique of catching prey instead of active searching.[13]

Traditional Reptilia
Simple phylogeny with Reptilia highlighted in green. Iguanians are within Lepidosauria.

Extant species

Image Scientific name Common Name Distribution
Lesser Antillean iguana Iguana delicatissima Lesser Antillean iguana the Lesser Antilles on Saint Barth, Anguilla, Sint Eustatius, Guadeloupe, Dominica, and Martinique
Chankanaab Park, Cozumel - panoramio - James Willamor (3) Iguana iguana Green iguana southern Mexico to central Brazil, the Dominican Republic, Paraguay, Bolivia and the Caribbean; specifically Grenada, Aruba, Curaçao, Trinidad and Tobago, St. Lucia, St. Vincent, and Útila


St Thomas Marriott Iguana 9 cropped

Green iguana from the island of St. Thomas

Caribbean iguana

Green iguana on St. Thomas

Iguana iguana male head

Another green iguana

Cayman Iguana

An invasive green iguana on Grand Cayman

Iguana in mexico

A green iguana at an environmental reserve at La Manzanilla, Jalisco, Mexico


A green iguana at Butterfly World, Stellenbosch, South Africa


A green iguana at Bannergatta, Bangalore, India

Iguana at at Indira Gandhi Zoological Park, Visakhapatnam

A green iguana in Indira Gandhi Zoological Park, Visakhapatnam, India


  1. ^ Cambridge Dictionary
  2. ^ Oxford Dictionaries
  3. ^ Coles, William (2002), "Green Iguana" (PDF), U.S.V.I. Animal Fact Sheet #08, Department of Planning and Natural Resources US Virgin Islands Division of Fish and Wildlife, archived from the original (PDF) on 2007-12-11
  4. ^ a b Chang, Cheng; Wu, Ping; Baker, Ruth E.; Maini, Philip K.; Alibardi, Lorenzo; Chuong, Cheng-Ming (2009). "Reptile scale paradigm: Evo-Devo, pattern formation and regeneration". The International Journal of Developmental Biology. 53 (5–6): 813–826. doi:10.1387/ijdb.072556cc. ISSN 0214-6282. PMC 2874329. PMID 19557687.
  5. ^ a b c Lazell, J.D. (1973), "The lizard genus Iguana in the Lesser Antilles", Bulletin of the Museum of Comparative Zoology, New York, 145, pp. 1–28
  6. ^ DABVP, Ryan S. De Voe DVM MSpVM DACZM. "Reptilian cardiovascular anatomy and physiology: evaluation and monitoring (Proceedings)". dvm360.com. Retrieved 2017-05-13.
  7. ^ Wada, Seiji (June 2012). "Expression of UV-Sensitive Parapinopsin in the Iguana Parietal Eyes and Its Implication in UV-Sensitivity in Vertebrate Pineal-Related Organs". PLoS One. 7: 6 – via PMC.
  8. ^ a b Lichtenbelt, Wouter D. van Marken (1993-08-01). "Optimal foraging of a herbivorous lizard, the green iguana in a seasonal environment". Oecologia. 95 (2): 246–256. Bibcode:1993Oecol..95..246V. doi:10.1007/BF00323497. ISSN 0029-8549. PMID 28312949.
  9. ^ a b Metzger, Keith A.; Herrel, Anthony (2005-12-01). "Correlations between lizard cranial shape and diet: a quantitative, phylogenetically informed analysis". Biological Journal of the Linnean Society. 86 (4): 433–466. doi:10.1111/j.1095-8312.2005.00546.x. ISSN 0024-4066.
  10. ^ Herrel, Anthony (2009). "Jaw and hyolingual muscle activity patterns and bite forces in the herbivorous lizard Uromastyx acanthinurus". Archives of Oral Biology. 54 (8): 772–782. doi:10.1016/j.archoralbio.2009.05.002. PMID 19481732.
  11. ^ a b "THE TEETH OF VERTEBRATE ANIMALS". inside.ucumberlands.edu. University of the Cumberlands. April 28, 2017. Retrieved April 28, 2017.
  12. ^ Banzato, Tommaso; Selleri, Paolo; Veladiano, Irene A.; Martin, Andrea; Zanetti, Emanuele; Zotti, Alessandro (2012-01-01). "Comparative evaluation of the cadaveric, radiographic and computed tomographic anatomy of the heads of green iguana (Iguana iguana), common tegu ( Tupinambis merianae) and bearded dragon ( Pogona vitticeps)". BMC Veterinary Research. 8: 53. doi:10.1186/1746-6148-8-53. ISSN 1746-6148. PMC 3439268. PMID 22578088.
  13. ^ a b c Vidal, Nicolas; Hedges, S. Blair (2009). "The molecular evolutionary tree of lizards, snakes, and amphisbaenians". Comptes Rendus Biologies. 332 (2–3): 129–139. doi:10.1016/j.crvi.2008.07.010. PMID 19281946.
  14. ^ Rest, Joshua S.; Ast, Jennifer C.; Austin, Christopher C.; Waddell, Peter J.; Tibbetts, Elizabeth A.; Hay, Jennifer M.; Mindell, David P. (2003). "Molecular systematics of primary reptilian lineages and the tuatara mitochondrial genome". Molecular Phylogenetics and Evolution. 29 (2): 289–297. doi:10.1016/S1055-7903(03)00108-8.

Further reading

  • Frost, D. R. (1989). "A phylogenetic analysis and taxonomy of iguanian lizards". Pub Univ Kansas. 81: 1–65.
  • Frost, D. R.; Etheridge, R.; Janies, D.; Titus, T. A. (2001). "Total evidence, sequence alignment, evolution of polychrotid lizards, and a reclassification of the Iguania (Squamata: Iguania)". American Museum Novitates. 3343: 1–39. doi:10.1206/0003-0082(2001)343<0001:TESAEO>2.0.CO;2.
Acclaim Studios Austin

Acclaim Studios Austin (formerly Iguana Entertainment) was an American video game developer based in Austin, Texas. The company was founded in 1991 by Jeff Spangenberg, previously lead designer for Punk Development, and originally located in Santa Clara, California. Iguana found first success with Aero the Acro-Bat, moved to Austin and acquired Optimus Software (later Iguana UK) in 1993. Iguana was acquired by Acclaim Entertainment in January 1995 and received another sub-studio, Iguana West in October that year. Spangenberg was fired from his position in July 1998 and filed a lawsuit on breach of contract the following October. Iguana was rebranded Acclaim Studios Austin in May 1999, and the studio was closed down in August 2004, followed by the Chapter 7 bankruptcy of its parent in September 2004.

Alfa Romeo Iguana

The Alfa Romeo Iguana is a concept car produced by Alfa Romeo in 1969. It was designed by Giorgetto Giugiaro at Italdesign.

Blue iguana

The blue iguana (Cyclura lewisi), also known as the Grand Cayman ground iguana, Grand Cayman blue iguana or Cayman Island rock iguana, is an endangered species of lizard endemic to the island of Grand Cayman. Previously listed as a subspecies of the Cuban iguana (Cyclura nubila), it was reclassified as a separate species in 2004 because of genetic differences discovered four years earlier. The blue iguana is one of the longest-living species of lizard (possibly up to 69 years).

The preferred habitat for the blue iguana is rocky, sunlit, open areas in dry forests or near the shore, as the females must dig holes in the sand to lay eggs in June and July. A possible second clutch is laid in September. The blue iguana's herbivorous diet includes plants, fruits, and flowers. Its coloration is tan to gray with a bluish cast that is more pronounced during the breeding season and more so in males. It is large and heavy-bodied with a dorsal crest of short spines running from the base of the neck to the end of the tail.

The fossil record indicates that the blue iguana was abundant before European colonization; but fewer than 15 animals remained in the wild by 2003, and this wild population was predicted to become extinct within the first decade of the 21st century. The species' decline is mainly being driven by predation by feral pets (cats and dogs) and indirectly by the destruction of their natural habitat as fruit farms are converted to pasture for cattle grazing. Since 2004, hundreds of captive-bred animals have been released into a preserve on Grand Cayman run by a partnership headed by the Durrell Wildlife Conservation Trust, in an attempt to save the species. At least five non-profit organizations are working with the government of the Cayman Islands to ensure the survival of the blue iguana. According to the November 9, 2013 episode of Ocean Mysteries with Jeff Corwin, the conservancy program has released over 700 captive bred Grand Cayman blue iguanas since the 2004 nadir of only 12 remaining animals.


Chuckwallas are large lizards found primarily in arid regions of the southwestern United States and northern Mexico. Some are found on coastal islands. The six species of chuckwallas are all placed within the genus Sauromalus; they are part of the iguanid family, Iguanidae.

Ctenosaura similis

Ctenosaura similis, commonly known as the black spiny-tailed iguana, black iguana, or black ctenosaur, is a lizard native to Mexico and Central America that has been introduced to the United States in the state of Florida. It is the largest species in the genus Ctenosaura and has been recorded as the fastest-running species of lizard.

Cyclura nubila

The Cuban rock iguana (Cyclura nubila), also known as the Cuban ground iguana or Cuban iguana, is a species of lizard of the iguana family. It is the largest of the West Indian rock iguanas (genus Cyclura), one of the most endangered groups of lizards. This herbivorous species with red eyes, a thick tail, and spiked jowls is one of the largest lizards in the Caribbean.

The Cuban iguana is distributed throughout the rocky southern coastal areas of mainland Cuba and its surrounding islets with a feral population thriving on Isla Magueyes, Puerto Rico. A subspecies is found on the Cayman Islands of Little Cayman and Cayman Brac. Females guard their nest sites and often nest in sites excavated by Cuban crocodiles. As a defense measure, the Cuban iguana often makes its home within or near prickly-pear cacti.

Although the wild population is in decline because of predation by feral animals and habitat loss caused by human agricultural development, the numbers of iguanas have been bolstered as a result of captive-breeding and other conservation programs. Cyclura nubila has been used to study evolution and animal communication, and its captive-breeding program has been a model for other endangered lizards in the Caribbean.

Galapagos land iguana

The Galapagos land iguana (Conolophus subcristatus) is a species of lizard in the family Iguanidae. It is one of three species of the genus Conolophus. It is endemic to the Galápagos Islands (Ecuador), in the dry lowlands of Fernandina, Isabela, Santa Cruz, North Seymour, Baltra, and South Plaza Islands.

Green iguana

The green iguana (Iguana iguana), also known as the American iguana, is a large, arboreal, mostly herbivorous species of lizard of the genus Iguana. Usually, this animal is simply called the iguana. The green iguana ranges over a large geographic area; it is native from southern Brazil and Paraguay as far north as Mexico and the Caribbean islands, and have been introduced from South America to Puerto Rico and are very common throughout the island, where they are colloquially known as gallina de palo ("bamboo chicken" or "chicken of the trees") and considered an invasive species; in the United States, feral populations also exist in South Florida (including the Florida Keys), Hawaii, the U.S. Virgin Islands and the Rio Grande Valley of Texas.A herbivore, it has adapted significantly with regard to locomotion and osmoregulation as a result of its diet. It grows to 1.5 metres (4.9 ft) in length from head to tail, although a few specimens have grown more than 2 metres (6.6 ft) with bodyweights upward of 20 pounds (9.1 kg).

Commonly found in captivity as a pet due to its calm disposition and bright colors, it can be very demanding to care for properly. Space requirements and the need for special lighting and heat can prove challenging to the hobbyist.


The Iguanidae are a family of lizards composed of iguanas and related species.

Jamaican iguana

The Jamaican iguana (Cyclura collei) is a large species of lizard in the family Iguanidae. The species is endemic to Jamaica. It is the largest native land animal in Jamaica, and is critically endangered, even considered extinct between 1948 and 1990. Once found throughout Jamaica and on the offshore islets Great Goat Island and Little Goat Island, it is now confined to the forests of the Hellshire Hills.

Krypto the Superdog

Krypto the Superdog is an American animated television series produced by Warner Bros. Animation, based on the DC Comics character Krypto. The show premiered on Cartoon Network on March 25, 2005, and aired on Kids' WB in September 2006. It would usually air after the Tickle-U block.

A comic book series (based on the TV show) was published by DC Comics under the Johnny DC imprint, which lasted 6 issues, from 2006 to 2007. The show was designed primarily for young children.

The show was produced in a manner reminiscent of the Hanna-Barbera shows of the 1960s to the 1980s, from the sound effects down to the animation style (veteran Hanna-Barbera designer Iwao Takamoto served as a creative consultant). The series is rated TV-Y.

The show was close captioned by the National Captioning Institute like many of Warner Bros. Animation's shows at the time.

Lesser Antillean iguana

The Lesser Antillean iguana (Iguana delicatissima) is a large arboreal lizard endemic to the Lesser Antilles. It is one of two species of lizard of the genus Iguana and is in severe decline due to habitat destruction, introduced feral predators, hunting, and hybridization with its introduced sister species, the green iguana (Iguana iguana). Successful captive breeding of this species has been limited to only two instances, as most captive-laid eggs tend to be infertile.

Another common name for it is the West Indian iguana, though this is more commonly used for species of the genus Cyclura.

List of Acclaim Entertainment subsidiaries

Acclaim Entertainment was an American video game publisher from Long Island, active from 1987 until filing for Chapter 7 bankruptcy on September 1, 2004. Through a series of acquisitions between 1990 and 2002, Acclaim built itself a large portfolio of subsidiaries acting in the fields of development and publishing.

List of Spider-Man enemies

Spider-Man is a fictional superhero in the Marvel Universe debuting in the anthology comic book series issue Amazing Fantasy #15 (August 1962) in the Silver Age of Comics published by Marvel Comics. After his debut he would get his own comic book entitled The Amazing Spider-Man. The comic book series would introduce many of what would become his major supervillain adversaries. Spider-Man would then be popular enough for more Spider-Man comic spinoffs (The Spectacular Spider-Man, Marvel Team-Up, Web of Spider-Man, Peter Parker: Spider-Man etc.) which introduced more recurring enemies of the web-slinger.

As with Spider-Man, the villains' powers originate with scientific accidents or the misuse of scientific technology and also tend to have animal-themed costumes or powers (Vulture, Doctor Octopus, Beetle, Lizard, Rhino, Scorpion, Jackal and Black Cat). There also are supervillains with the powers over the elements (Sandman, Shocker, Electro, Molten Man and Hydro-Man), some that are horror-themed (the Goblins, Morbius, Morlun, and the Symbiotes) some that are crime lords (Kingpin, Tinkerer, Tombstone, Hammerhead, Silvermane and Mister Negative), and some that are masters of trickery and illusion (Chameleon and Mysterio). These villains oftentimes form teams such as the Sinister Six to oppose the superhero.

The rogues gallery of Spider-Man has garnered positive critical acclaim and has been considered as one of the greatest rogues galleries of all time.

Marine iguana

The marine iguana (Amblyrhynchus cristatus), also known as the sea iguana, saltwater iguana, or Galápagos marine iguana, is a species of iguana found only on the Galápagos Islands (Ecuador) that has the ability, unique among modern lizards, to forage in the sea, making it a marine reptile. This iguana feeds almost exclusively on algae and large males dive to find this food source, while females and smaller males feed during low tide in the intertidal zone. They mainly live in colonies on rocky shores where they warm after visiting the relatively cold water or intertidal zone, but can also be seen in marshes, mangrove and beaches. Large males defend territories for a short period, but smaller males have other breeding strategies. After mating, the female digs a nest hole in the soil where she lays her eggs, leaving them to hatch on their own a few months later.Marine iguanas vary in appearance between the different islands and several subspecies are recognized. Although relatively large numbers remain and it is locally abundant, this protected species is considered threatened, primarily from El Niños, introduced predators and chance events like oil spills.

Mona ground iguana

The Mona ground iguana (Cyclura stejnegeri) is a species of Cyclura closely related to the rhinoceros iguana (Cyclura cornuta). It is endemic to Mona Island, Puerto Rico and is the largest native terrestrial lizard in Puerto Rico.


The RG-34 (formerly denoted as Iguana FV4) is a South African MRAP. Specially designed to be mine-resistant, it has been produced in multiple variants, equipped for troop or cargo transport, command, and fire support. Originally showcased with a wide turret ring and a 90mm rifled cannon, the RG-34 was one of the first MRAPs configured to carry a large gun system.

Rhinoceros iguana

The rhinoceros iguana (Cyclura cornuta) is a threatened species of lizard in the family Iguanidae that is primarily found on the Caribbean island of Hispaniola, shared by the Republic of Haiti and the Dominican Republic. They vary in length from 60 to 136 centimetres (24 to 54 in) and skin colours range from a steely grey to a dark green and even brown. Their name derives from the bony-plated pseudo-horn or outgrowth which resembles the horn of a rhinoceros on the iguana's snout.

The Night of the Iguana

The Night of the Iguana is a stage play written by American author Tennessee Williams, based on his 1948 short story. First staged as a one-act play in 1959, Williams developed it into a full-length play over the next two years, staging two different versions in 1959 and 1960, before arriving at the three-act version of the text which premiered on Broadway in 1961. Two film adaptations have been made, including the Oscar-winning 1964 film directed by John Huston and starring Richard Burton, Ava Gardner, and Deborah Kerr. The other is a 2000 Croatian production.


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