Green Iguana Society logo  1999-2001, D. Baze

Sexing An Iguana: Male vs. Female - One of the most common questions new iguana owners have is, "How can I tell what sex my iguana is?" Owners must keep in mind that the sex of an iguana cannot be determined until the iguana has reached sexual maturity. Juveniles of both sexes look alike and will not show any secondary sexual characteristics until they reach maturity. Sexual maturity in iguanas is a function of size rather than age. Males may become sexually mature once they reach 6" SVL. Females will usually take a bit longer, and will not mature until they reach about 10" SVL. Depending upon the care of the iguana, its age at maturity may vary a bit, but it usually falls somewhere in between 1.5 - 2 years.

Another question often asked is, "Is there any advantages of having one sex over the other?" Males and female iguanas differ on many ways. Both present distinct sets of challenges to their owners, especially during breeding season.
For more information on breeding season, please visit our Breeding Season Issues page.

Males

Physical Characteristics - At maturity, males show several secondary sexual characteristics. One of the most easily identified is the large jaw muscles on either side of the lower jaw, below the ear. These muscles produce large, swollen-looking "jowls". Males have large, blocky heads, and the jowls add to this effect. Males also have two fatty deposits on their forheads, behind the eye and above the ear. These also add to the size and blocky shape of the head.

Here is a photo of Jake, a mature male. Notice the fatty bumps behind the eye and above the ear. You can also see Jake's jowls, with the large subtympanic shield scales (for an explanation of anatomical terms, see our Anatomy page).

This is Brownie, who is also a mature male. This photo, taken from underneath the chin, gives a great view of the swollen jowls.

Males also tend to have longer dorsal spikes along their back, especially along the neck area. Another indication that an iguana is a male is the large pores that are visible along the inner thigh. These pores, called femoral pores, are easily visible in males, and are often filled with a waxy substance.

Here is another photo of Jake. Notice his large, easily visible femoral pores. This photo was taken when Jake was not in breeding season.

Two other male characteristics are a heftier, heavier body and a bulge near the base of the tail where the hemipenes are located.

 

Females

Physical Characteristics - The easiest way to identify a female iguana is by the absence of male secondary sexual characteristics. Their heads are smaller and more streamlined, and lack the fatty deposits behind the eyes and the more pronounced jowls.

This is Donnie, a mature female. Her head is smaller. Notice that she lacks the fatty deposits and the larger, more pronounced jowls.

In addition to having smaller heads, females also have small femoral pores which do not develop waxy protuberances.

Here is another photo of Donnie. Notice her small femoral pores.

Females tend to have longer, slimmer bodies than males and lack the hemipenal bulge near the vent.








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