Added 27 April 2008. Last updated 9 May 2008.

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Genus Iguana - Green Iguanas


Genus Iguana - Green Iguanas

Green iguanas are without doubt one of the most charismatic lizard species today. Equally, they have been recently one of the most problematic (see Plight of the Green Iguana).

Hazell gives the following definition of the genus: iguanid lizards with femoral pores; a pendulous, longitudinal dewlap; dorsal crest consisting of single, elongate scales; ilial shaft broad, hardly tapering, posteriorly blunt, inclining smoothly anteriorly to form the dorsal surface of a heavy anterior iliac process; a large secondary coracoid fenestra; basisphenoid greatly expanded laterally beyond basipterygoid processes; a low finlike process above neural arch of no more than six anterior caudal vertebrae.

Of these characteristics it is probably safe to say that one can easily remain in ignorance of them and still easily recognise Iguana iguana. The only species which which one might confuse it in the wild is some of the Ctenosaura or Cyclura species, which however lack the enlarged round scale (the subtympanic scale) below the ear. However this is not present in Iguana delicatissima, which however has a much smaller range and is unlikely to be seen in pet stores. In captivity for the same reason I. iguana is hard to mistake for the Asian Water Dragon Physignathus concincus

The genus comprises just two species, Iguana iguana which is widespread through Central and northern South America, and Iguana delicatissima which is confined to and is not seen in the pet trade. Green iguanas are creatures of the rainforest, high humidity and a herbivorous and varied diet. Formidably sized lizards, they are nevertheless prey for certain other species including man. Inevitably in poorer societies, hungry people seek other sources of protein. Up to a certain level this is sustainable, but mass collecting for either the pet trade or for the dinner table is not so. There has been talk in recent years of "ranching" or "captive farming" of green iguanas.

It is not the place of this page to provide comprehensive care details for this species, not least because others have already done so (see Bibliography). However, a few pointers should suffice. Green iguanas need large, tall cages that can be kept fairly humid, good UV lighting and a varied and totally herbivorous plant diet. They are not recommended as pets for families with small children (under 5) because of the reputation for carrying salmonella. In addition, since males have proportionately the largest testes of any land vertebrate, they can become quite "driven" when in full hormonal flush. Having said this, if you can meet this requirements and believe the risk of salmonella can be contained, then "igs" can make very intelligent and interesting reptilian household animals.

For a long time it was generally believed that the average life expectancy of a captive Green Iguana was 10-15 years. However a short article in Herpetological Review 28:4 by Karel L Rogers cited a female purchased in 1968 as a hatchling that died in 1996, giving an authenticated longevity of over 27 years. Given the often poor captive regime under which many Green Iguanas have suffered in the past, this constitutes both a rebuke and an encouragement to keepers.

A full Bibliography and Links section is given at the bottom of the page which I recommend especially to people considering a Green Iguana as a pet.

Scientific Name Common Name Distribution Size Notes
I. delicatissima West Indian Iguana, Lesser Antillean Iguana Lesser Antilles SVL Identical in most ways to Iguana iguana, but can be distinguished from the latter by its lack of an enlarged subtympanic scale. In the Antilles [SOURCES: Lazell].
I. iguana Green Iguana Mexico south through Central and northern South America as far as Peru, Bolivia and Paraguay; in the Caribbean, the Antilles; introduced into the USA in Florida and Hawaii SVL 20-40cm/8-16": tail nearly 3 times SVL Easily identifiable by the enlarged subtympanic scale. One thing to note is that Green Iguanas in the wild are opportunistic and will take a variety of foods (including protein-rich sources such as birds' eggs, fish and even carrion) that are contraindicated for a captive diet. This adaptability seems to be a two-edged sword for the species, since in captivity anything other than a strictly herbivorous diet appears to lead to long-term kidney problems and a shortened lifespan. Scalation details: enlarged triangular scales on dewlap; middorsal row of high, narrow scales extending along body onto tail; scales on upper surfaces of body small, juxtaposed, keeled and larger than lateral scales; scales on undersurfaces of body smooth, imbricate, larger than scales on upper surfaces; uppoer surfaces of head covered with enlarged, symmetrically arranged plates; upper surfaces of limbs covered with keeled imbricate scales, undersurfaces with smooth scales; enlarged spinose tubercles usually present on sides of neck. Other: body rather compressed laterally; snout rounded; eye large, with vertical pupil; 18-20 femoral pores on undersurfaces of each thigh, larger in the males. Coloration: young are bright green; this usually fades with age so that older individuals become greenish grey, tan or brown, with dark vertical bars on the sides of the body and the tail marked with alternate light and dark bands of equal width. Males often have orange or orange-green on the head, limbs or lower parts of the body Reproduction details: males are generally larger, with larger femoral pores. [SOURCES: Lazell, Lee].
I. i. iguana        
I. i. rhinolopha        


"The lizard genus Iguana in the Lesser Antilles", James D Hazell Jr, Bulletin of the Museum of Comparative Zoology, Harvard University, Vol 145 Number 1, 23 May 1973.

A Field Guide to the Amphibians and Reptiles of the Maya World, Julian C Lee, Cornell University Press, 2000.

Green Iguana Manual, Philippe deVosjoli. The earlier version of this manual has been criticised for offering out-of-date and incorrect information on nutrition, so the reader is advised to go for this 2003 edition.

Green Iguanas, Bartlett & Bartlett

Giant Lizards, Robert Sprackland, TFH 1996. A useful book on many of the larger species, although possibly now a bit behind with the taxonomy.

"Elderly Iguana", brief article in the R&A Quicks section of Reptile Hobbyist 3:7, cites the article in Herpetological Review 28:4 mentioned in the Introduction above.

See also Index of Iguanid Related Articles for articles on Iguana in the wild and in captivity.

I have not read the following, but the first has been highly recommended, the second is by the very experienced Melissa Kaplan and the third by the equally experienced reptile veterinarian Frederic Frye:

Green Iguana: The Ultimate Owners' Manual, James W Hatfield III, 2004 (paperback edition). At over 600 pages long this is certainly comprehensive. Virtually all reviews I have read have been highly positive.

Iguanas for Dummies, Melissa Kaplan, 2000. Possibly it depends whether you like the "Dummies...." format, but this is still a good price for a book from an expert.

Iguana iguana: Guide for Successful Captive Care, Frederic L Frye, Krieger 1995.


Melissa Kaplan's website deals very much with Green Iguanas, and has been doing so for many years.

The Green Iguana Society of US and Canada provides care information as well as providing information and help with rehoming and adoption.

Iguana Answers is a UK-based site providing similar information.

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