The green iguana is among the best known Amazon reptiles, being raised widely as a pet. One thing true
about the green iguana is that people who own one are invariably passionate about their iguana!
The iguana body is typically lizard-like, with a prehistoric appearance emphasized by a dorsal crest
running along the back. The crest's comb-like spines may deter predators. The iguana has a large
head, with a rounded snout and powerful jaws. Although vegetarian, it can inflict a nasty bite.
The skin is covered with tiny scales which ma darken upon exposure to sunlight. (They do not have the
color-changing ability of chameleons.)
The iguana has robust strong limbs, and the digits bear long claws ideal for gripping branches, an
essential adaptation to its arboreal
lifestyle. As many iguana owners will testify know, the claws are capable of causing painful scratches.
However, they are non-aggressive animals and rarely attack without provocation.
Its tail tapers to a whip-like end, serving as defense when cornered. The tail is longer than the body,
about two thirds the animal's length. Like many other lizards, the tail breaks off at the base if
predators threaten, and will quickly grow back, apparently causing no permanent harm.
Young iguanas are bright green while the scales of the mature adult are more gray than green although the
tail has a series of vertical yellow-green stripes.
The iguana bears highly modified scales, slightly prodtruding that are sometimes mistaken for
eardrums. The ears are located above these, in small pits below and behind the eyes. The function of these
modified scales is not known. They may serve in species recognition, or perhaps to distract predators away
from the eyes.
Along the throat, on the underside of the neck is a loose membrane of skin, the dewlap. This is
important in thermoregulation and plays a role in courtship and territrial displays.
A full grown iguana is one of the largest arboreal reptiles, reaching 6 or 7 feet in length.
HABITAT AND DISTRIBUTION
The green iguana has among the greatest ranges of large New World reptiles, found from northern Mexico to
the South American tropics. However, its local distribution is restricted by its habitat preference. It
is primarily arboreal, a forest-dweller, and in particular favors riverside forest, basking and foraging
among branches overhanging slow-moving rivers. They prefer low-lying regions such as the flooded forest
regions of Amazonia and are not found above 3,000 feet.
The iguana rarely ventures to the ground and if threatened by a predator leaps into the water (sometimes
onto the ground) for safety. Wild iguanas are very cautious and hide or run at a hint of danger. When
swimming, they hold their legs to the sides and propel themselves with sinuous swipes of the tail (in the
manner of a crocodile). If necessary, they can stay submerged for a long time.
FEEDING AND DIET
Iguanas are generally vegetarian, but otherwise have a broad diet of fruit, leaves, flowers and other
plant matter. Juveniles may feed on insects and other invertebrates. The lizard is active primarily
during the day, basking in the morning light to warm up for feeding activity and then in the setting sun
to aid digestion.
The green iguana is sexually
dimorphic. That is, the sexes differ in appearance. The head and dewlap of the male is more
prominent, and he is larger in overall body size. Males also tend to be more brightly colored than
females, particularly during the breeding season. The female deposits her eggs into a nest 3 or 5
feet long and 2 feet deep. She lays over two or three months, a total of 25 to 50 eggs.
The undersides of the thighs of both sexes bear a row of dozen or so pores arranged. These glands secrete
a wax-like substance that the iguanas spread on branches to mark their territory. In mature males, these
pores protrude somewhat, perhaps to give the male a better grip during copulation.
Early in the year, around January or February mating season commences. Gestation lasts about 2 months,
and then the female excavates a nest near the base of a tree, in moist sand or soil. She lays 25 to
40 eggs and about two weeks later, they hatch. The hatchlings grow 6 to 10 inches a year and are
sexually mature in about 3 years.
The young are pale green with black-ringed tails having five to seven black rings. Older iguanas lighten in
color, but retain the dark vertical bars on the body and tail.
Iguanas live about 15 years in captivity. Presumably, their lifespan in the wild is somewhat shorter.
The green iguana is locally abundant where its habitat remains intact and is not threatened with
extinction at present. However, it is widely hunted, being much favored for its tasty meat. For this
reason, it is nicknamed "chicken of the forest" in Amazonia (or "bamboo chicken" in
Central America). Local people will take iguana eggs if they find the nest.
Several attempts have been made to commercialize the raising of iguanas for sale. (Read article.) Scientific studies
have looked at managing natural populations to provide a sustainable yield. The hope is that such
ranching projects will relieve hunting pressure on wild populations while at the same time providing
incentive to preserve critical habitat.
Some experts doubt the potential for success of these projects given the hurdle of selling these reptiles as
anything more than a novelty food to markets outside their local range.