Iguana
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| Iguana | ||||||||||||||
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A green iguana (Iguana iguana) | ||||||||||||||
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Iguanas are relatively large lizards of the family Iguanidae. They often have spiny projections along the back. There are other members of the family Iguanidae in the "traditional" classifiction but this article considers the "true" iguanas of the subfamily Iguaninae
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[edit] Habitat and behavior
Iguanas live in many different environments, Most live in tropical rainforests, mostly in lower altitudes in areas near water sources, like rivers or streams. They spend most of their time high in the forest canopy, about 40-50 feet (12 meters) above the ground. Others iguanas live on rocky terrains, deserts or marine enviroments. Some iguanas dig burrows.
Iguanas are mainly diurnal and forest species pefer to laying in the shade. Green Iguanas in particular are mostly mild placid creatures. However males can be extremely aggressive and territorial during the females' menstrual cycle. Courtship displays of male iguanas include push-up behaviors and puffing up of the dewlap.
[edit] Anatomy
[edit] Limbs
Terrestrial iguanas have long legs and toes that enable them to run great distances. Iguana that have adapted to living on rockey terrain have short and stout limb with strong claws that make them great climbers. Arboreal iguanas have long, slender limbs while marine iguanas have webbed feets for swimming.
[edit] Eyes and vision
Iguanas have excellent vision. They can detect shapes and motions at very long distances. Iguanas have only a few rods and thus have poor vision in dim light. At the same time they have cells called “double cones” that give them sharp color vision.
Iguanas can also see ultraviolet wavelenghts, which is highly useful when basking. The iguana is able to ensure that it gets enough vitamin production in its skin for proper mineral uptake. In addition, its sensitivity to these wavelengths help it choose favored tidbits of food since flowers shine brightly in ultraviolet wavelengths.
Iguanas have evolved a white photosensory organ on the top of their heads called the parietal eye, which are also called third eye, pineal eye or pineal gland. This “eye” doesn’t work the same way as a normal eye does. It has only a rudimentary retina and lens and cannot form images. It is however sensitive to changes in light and dark and can detect movement. This helps the iguana when being stalked by predators from above. Many species of skinks and agamids also have this “eye.”
[edit] Teeth
Iguana have very sharp teeth that are capable of shedding leaves and even human skin. The teeth are situated on the inner sides of the jawbones which is why they are hard to see in smaller specimens.
[edit] Other features
Iguana have lots of spines along their backs and along their tails which help protect them from predators. Their tails can be used like whips and can be painful. When grabbed by the tail, an iguana can break its tail, escape and regrow a new one. This trick is done by many lizards. In addition, most iguanas have well developed dewlaps which helps regulate body temperature. It is also used in courtships and displays.
[edit] Diet
Iguanas are regarded as omnivores, but usually consume plants, mainly leaves and fruits. Sometimes iguanas (especially younger ones) eat eggs, insects and other smaller vertebrates. Although Green Iguanas in captivity will eat animal food if presented with it, excessive consumption of animal protein may result in severe health problems and possible premature death [1]. Another problem with domesticated diet is lack of variety. Many people tend to feed them just lettuce, which provides iguanas with plenty of water but has little or no other nutritional value. Several pet stores also sell iguana food pellets, however these should always be supplemented with a diet of fresh leafy vegetables (such as mustard greens, collard greens, and kale) and other types of fresh fruits and vegetables.
[edit] Reproduction
Like other reptiles, iguanas are oviparous. They can lay from 1-45 eggs depending upon the species. They are also polygynandrous. Once hatched, the young iguanas look and act like the adults. They tend to resemble adult females more then males. Iguana give no parental protection and the hatchlings can fend for themselves.
[edit] As invasive species
Iguanas can be considered an invasive species in South Florida[2] and along the gulf coast of Florida, especially on Gasparilla Island (where there is an estimated population of over 12000).[citation needed]This is due to a combination of escaped and intentionally released iguanas which have survived and then thrived in their new habitat. They commonly hide in the attics of houses and on beaches and often destroy gardens. As an introduced species, they contribute to natural habitat loss, spread salmonella, and may be responsible for the recent decline of the gopher tortoise.[citation needed] An interesting thing is that they can by unknown means end their own life, probably by releasing toxins.[citation needed]
[edit] As pets
Main article: Green Iguana in captivity
Most iguanas kept as pets are green iguanas
A maximum commitment to an ideal iguana, yields an excellent companion, able to be taken outside, greet passersby, observe cars passing (unafraid), travel (un-caged) in a vehicle for extended periods (Note: iguanas love to hide, do not allow the iguana to crawl into the dash or air conditioning system!). A pet iguana should be very observant, confident, and curious; willing to give affection by nuzzling or single licks (lizard kisses) and also share your bed (not recommended). Iguanas can be "potty-trained" to go outside (when it is warm), go in a specific location (as on newspaper) or in a tub of warm water (and even on the toilet).[3]
An iguana pet should never be left outside unattended unless the iguana is in a partly-shaded (half shaded, half sunny), secure enclosure and the ambient air temperature in a range of 80 to no more than 100 degrees F. Extreme care must be given if a captive iguana is exposed to direct sunlight and never in a glass enclosure or un-occupied vehicle. Fifteen minutes of direct sun exposure each day (if possible) will enable the iguana to convert calcium metabolically (as vitamin D3 is synthesized in the skin the same way it is in humans).[4] Iguanas overheat quickly in intense sunlight and will "pant". An iguana should feel slightly warm to the touch, never "hot" (if an iguana has been basking under artificial light/heat it may feel quite warm) or "cold". Iguanas cannot properly digest food unless a very narrow heat range is maintained, usually 75 to <100 degrees F. Ideally the iguana should be able to "choose" at any time to be hotter or cooler. The heat range must vary from low end to high every day for the iguana's physical and mental health. Iguanas often require medical care for injuries, skin infections (including mouth), diet related problems, kidney failure, or spay/neutering. An ordinary veterinarian does not have the training to deal with an iguana. Before obtaining an iguana, check to see that there is a veterinarian in your area certified to treat "exotic pets".[5]
If properly cared for, a captive green iguana can live anywhere from 15 to 20 years.[6]
[edit] Species in the genus Iguana
(after Frost et al.)
- Lesser Antillean Iguana, Iguana delicatissima
- Green Iguana, Iguana iguana
[edit] Taxonomy
Two different classification schemes have been used to define the structure of this family. These are the "traditional" classification and the classification presented by Frost et al. (1989).
Frost et al. redefined this family. The genera belonging to the different subfamilies were assigned to separate families. This view is not generally accepted and the 'traditional' classification is still widely used.[citation needed]
[edit] Frost et al classification of iguanas
Family Iguanidae
- Genus Amblyrhynchus
- Genus Brachylophus
- Genus Conolophus
- Genus Ctenosaura
- Genus Cyclura
- Genus Dipsosaurus
- Genus Iguana
- Genus Sauromalus
- Genus Armandisaurus (extinct)
- Genus Lapitiguana (extinct)
- Genus Pumila (extinct)
[edit] Traditional classification
- [citation needed]
Family Iguanidae
- Subfamily Corytophaninae: casquehead lizards
- Subfamily Crotaphytinae: collared and leopard lizards
- Subfamily Hoplocercinae: wood lizards, clubtails
- Subfamily Iguaninae: iguanas and spinytail iguanas
- Subfamily Leiocephalinae
- Subfamily Leiosaurinae
- Subfamily Liolaeminae
- Subfamily Oplurinae: Madagascar iguanids
- Subfamily Phrynosomatinae: earless, spiny, tree, side-blotched and horned lizards
- Subfamily Polychrotinae: anoles
- Subfamily Tropidurinae: neotropical ground lizards
[edit] Iguanas In Popular Culture
Godzilla (1998 film) features a herd of Iguanas. But one of them mutates into Zilla, a giant Dinosaur-like creature who plans to nest in New York and make the city into a jungle of mutated Iguanas. This Iguana's life continues in Godzilla: The Series.