Iguana

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Iguana
Temporal range: Holocene–Recent[1][2]
A green iguana (Iguana iguana)
CITES Appendix II (CITES)[3]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Iguania
Family: Iguanidae
Genus: Iguana
Laurenti, 1768
Type species
Linnaeus
, 1758
Species
Synonyms
  • Hypsilophus Wagler, 1830
A male green iguana

Iguana (

naturalist Josephus Nicolaus Laurenti in his book Specimen Medicum, Exhibens Synopsin Reptilium Emendatam cum Experimentis circa Venena. Two species are placed in the genus: 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. Genetic analysis indicates that the green iguana may comprise a complex of multiple species, some of which have been recently described, but the Reptile Database considers all of these as subspecies of the green iguana.[6][7]

The word "iguana" is derived from the original

Taino name for the species, iwana.[8]
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".[9]

The species is a popular quarry for

Florida Peninsula, Hawaii, Singapore, Thailand, Taiwan, and including numerous islands with native Iguana populations in the Lesser Antilles.[7][10]

Anatomy and physiology

Iguanas are large

ventral sides.[11] 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 subtympanic shield.[12]

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.[12]

The

tympanum, the iguana's eardrum
, is located above the subtympanic 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.[12]

Like most

systemic circulation.[13]
The muscles of an iguana are very light in color due to the high proportion of
fast-twitch, glycolytic muscle fibers (type A). These A fibers are not very vascularized and are low in myoglobin, giving them their pale look. This high density of A 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 A fibers is anaerobic
.

Parietal eye

Several species of lizards, including the iguanas, have a pale scale towards the back of their heads marking the

ultraviolet light and aids in the signaling between day and night.[14]

Skull morphology and diet

Iguanas have an exclusively herbivorous diet,[15] as illustrated above by a green iguana eating a mango in Venezuela.

Iguanas have developed an

biomechanically, herbivorous lizards have taller and wider skulls, shorter snouts, and larger bodies relative to carnivorous and omnivorous reptiles.[16] Increasing the strength of the skull allows for increased muscle presence and increases the ability of the skull to withstand stronger forces.[17]

Albino Iguana - Bred to be kept as a pet
Green iguana skull (Iguana iguana).jpg: Brian Gratwicke derivative work: B kimmel (talk)
Green iguana skull and teeth: The teeth of the green iguana sit on the surface of the jawbone, known as acrodontal placement.[18]
Simple phylogeny with Reptilia highlighted in green: Iguanians are within Lepidosauria.

Furthermore, the teeth of the iguana are acrodontal, meaning that their teeth sit on top of the surface of the jaw bone[18] and project upwards. The teeth themselves are small and serrated - designed to grasp and shear food.[19]

Reproduction

Male iguanas, like other male examples of Squamata, have two hemipenes. During copulation, one hemipenis is inserted into the female's cloacal vent.[20] A female 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.[21][22][23]

Mating/courtship

Iguanas tend to follow a promiscuous or

r-strategy reproduction.[citation needed
]

Phylogeny

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).[24] The phylogeny based on whole mitochondrial genomes, though, as proposed by Rest et al. (2003), places the green iguana as the closest relative of the mole skink (Plestiodon egregius).[25] Lepidosaurs are reptiles with overlapping scales, and within this group both iguanians and tuataras (Sphenodon) project their tongues to seize prey items instead of using their jaws, which is called tongue prehension. Iguanians are the only lineage within the Squamata that display this trait, meaning that it was gained independently in both iguanians and tuataras.[24] 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.[24]

A study by Breuil et al. (2020) found the taxonomy of the genus Iguana as follows, with I. delicatissima being the most basal member of the group.[6] The species are classified as subspecies based on the ReptileDatabase definitions.

Sauromalus

Iguana

I. delicatissima

I. iguana

"

I. i. rhinolopha
"

I. i. melanoderma

I. i. iguana

The Reptile Database synonymizes I. rhinolopha with I. iguana, only considering it a distinctive population, and recognizes I. insularis and I. melanoderma as subspecies of I. iguana. Four subspecies of green iguana are recognized under this treatment: I. i. insularis (Saint Vincent & the Grenadines and Grenada), I. i. sanctaluciae (Saint Lucia), I. i. melanoderma (parts of the northern Lesser Antilles, and potentially coastal Venezuela, the Virgin Islands, and Puerto Rico), and I. i. iguana (mainland South America).

Extant species

Two extant species in the genus Iguana are widely recognized.

Image Scientific name Common name Distribution
Iguana delicatissima Lesser Antillean iguana The
Iguana iguana Green iguana Most of
Útila
.

Subspecies

Three Caribbean subspecies of the green iguana are also recognized:

Image Subspecies Common name Distribution
I. i. insularis[26] Grenadines horned iguana St. Vincent and the Grenadines and Grenada
Iguana iguana melanoderma[6] Saban black iguana Saba, Montserrat, and formerly Redonda, but also possibly coastal Venezuela, the Virgin Islands, and Puerto Rico (at least parts of this range may derive from (pre)historic introductions).
I. i. sanctaluciae[26] Saint Lucia horned iguana St. Lucia

The Central American iguana (I. rhinolopha or I. i. rhinolopha), sometimes considered a distinct species, is largely considered synonymous with I. iguana, as the presence of horns does not necessarily indicate a new species or subspecies. The two described subspecies of I. insularis (the Saint Lucia horned iguana, I. i. sanctaluciae, and the Grenadines horned iguana, I. i. insularis) were originally described as subspecies of I. iguana, although they are genetically very similar and may not be separate subspecies from one another.[27] Recent studies have recovered I. rhinolopha and I. insularis as distinct species based on genetics, but the Reptile Database disagrees with these conclusions, and classifies I. rhinolopha as synonymous with I. iguana, and I. insularis as a subspecies of I. iguana.[28] The Curaçao population of green iguanas shows major genetic divergence and may also represent an as-of-yet undescribed species or subspecies.[6][29]

As food

Iguanas have historically featured in the culinary traditions of Mexico and Central America. Iguana meat is also consumed in parts of the United States and Puerto Rico.[30] Also, the eggs of iguana are consumed in some parts of Latin America, such as Nicaragua and Colombia.[31]

References

  1. ^ "Fossil works: Iguana iguana".
  2. ^ "Fossil works: Iguanidae".
  3. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  4. ^ Cambridge Dictionary
  5. ^ Oxford Dictionaries
  6. ^
    PMID 32336922
    .
  7. ^ a b "Iguana iguana". The Reptile Database. Retrieved 2021-04-26.
  8. ^ 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
  9. ^ Wildlife Review. U.S. Department of the Interior, Fish and Wildlife Service. 1968.
  10. S2CID 257731680
    .
  11. ^ .
  12. ^ a b c Lazell, J.D. (1973), "The lizard genus Iguana in the Lesser Antilles", Bulletin of the Museum of Comparative Zoology, vol. 145, New York, pp. 1–28
  13. ^ DABVP, Ryan S. De Voe DVM MSpVM DACZM. "Reptilian cardiovascular anatomy and physiology: evaluation and monitoring (Proceedings)". dvm360.com. Archived from the original on 2018-11-06. Retrieved 2017-05-13.
  14. PMID 22720013
    .
  15. ^ .
  16. ^ .
  17. .
  18. ^ a b "THE TEETH OF VERTEBRATE ANIMALS". inside.ucumberlands.edu. University of the Cumberlands. April 28, 2017. Archived from the original on January 18, 2021. Retrieved April 28, 2017.
  19. PMID 22578088
    .
  20. .
  21. ^ "The Mating Behavior of Iguana iguana".
  22. ^ "Iguana Behavior- Coterc" (PDF).
  23. .
  24. ^ .
  25. .
  26. ^
    S2CID 182634075. Archived from the original
    on 2020-04-14. Retrieved 2020-08-04.
  27. ^ "Iguana iguana". The Reptile Database. Retrieved 2020-04-15.
  28. S2CID 59353644
    .
  29. .
  30. . Retrieved 2020-01-23.
  31. ^ "Nicaragua's Government Suggests Eating Iguana as Massive Food Crisis Looms". Vice. 20 August 2014. Retrieved 21 February 2020.

Further reading

External links

  • Media related to Iguana at Wikimedia Commons
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