Green iguanas are large, tree dwelling, lizards of the New World family Iguanidae. Some of the obvious features of green iguanas include their long tails, a permanent dewlap beneath their throat, and enlarged scales beneath the ear drum. Both males and females have a single row of femoral pores on the underside of the thighs. "The Green Iguana comes from Mexico to Southern Brazil, Paraguay and in the Lesser Antilles" (Vosjoli 2). The name "iguana" is a Spanish version of the carib word "iwana." .
There is a considerable variation in the potential adult size of green iguanas, depending on the country of origin and the conditions by which they live. As a main rule for iguanas they usually will achieve a length of four to five feet, with occasional specimens reaching a length of six feet. Some males of South American populations can reach a length of nearly seven feet and weigh up to eighteen pounds.
There are several sexual characteristics of green iguanas. Males grow larger than the females, but are not as heavy bodied as females. In general, males develop larger dorsal crests and have larger scales beneath the tympanum than females. However, some females have enlarged scales beneath the tympanum as large as that of some males. In older iguanas, at least two years old, the femoral pores of males will be significantly more enlarged than that of females and will produce femoral pore secretions that resemble enlarged scales. Older males will also develop broad enlarged jowls which are definite signs of a male. .
"Within three years a baby iguana will grow from a half ounce hatchling to a two and a half pound adult; a hundred fold increase in weight" (Vosjoli 5). After several years, large iguanas can reach a weight of ten to fifteen pounds. For iguanas to achieve a weight of this degree they must have effective digestion, enough calcium to build skeletal tissue, and eat large amounts of food.