Iguana Gender: Is it a boy or girl?!

by Catherine E. Rigby

Last revised Nov 1997

FEMORAL PORES

Many iguana care books provide drawings or photographs of the femoral pores -- a line of dots tracing along the upper inside of the thighs. In baby iguanas, they are barely discernible pin pricks but in older babies at least 12-18 months old, the pores can be a good clue as to what sex the iguana may be.

In older juveniles or adults, the difference is easily noted. The female pores are very small, and the male pores are enlarged, often with nubby, waxy, comb-like protrusions. The male iguana will wear them down himself, they do NOT need to be removed or cleaned out. In fact, forcibly removing them can cause you iguana some harm. They are NOT to be confused with seminal plugs or seminal exudates.

Sub-Adult Female Pores are very small along inside of thigh.

Sub-Adult Male Pores are large, with waxy protrusions.

TAIL SHAPE.

The general shape of the tail can also be a clue as to gender. Female tails tend to taper down almost immeditaely after the vent. Because of the hemipenal bulges, the male's tail is usually "thicker" and does not taper off as soon as the female tail does. I've noticed males also tend to have slightly puffier vents. It is easier to see the hemipenal bulges if the iguana is turned to his side. A cross section of the iguana tail near the vent may show the female to be more circular, and the male more oval-shaped.

BODY SHAPE

Overall, grown females tend to have sleek heads, narrow necks, but incredibly dumpy middles. Grown males tend to have impressive jowled heads, possibly longer spikes, but a leaner body. Both sexes can have orange coloring during breeding season.  This can vary from a very bright orange color on the arms, legs, back and head regions, to a vague overall "tint" that looks like a light misting of orange over the regular colors of the iguana. Other iguanas will have "patches" of orange, or may not even turn orange at all. Color is not a reliable means of determining gender.

OTHER CLUES.

Males tend to leave behind seminal plugs/exudates when in season. Some continue to produce these annoying "gifts" even out of season after they mature. Seminal plugs, when fresh, are usually straight, amber-white and resemble melted cheese. If they have been caught up in the feces of the iguana, they might have a brown or black tip. When dried, they turn amber-golden, and tend to curl.

Dry Seminal Plug.

Seminal plugs can sometimes get caught up with feces inside the iguana and can be found stuck in the vent. They should be removed in order to prevent more build-up of feces and later on, blockage of the iguana. Simply soak the iguana in a warm bath (approx 85 deg F) and gently massage the plug out. Leaving a seminal plug in the vent can lead to trouble as it grows larger and the iguana is unable to pass it out or has problems defecating.

Semninal exudates are similar to plugs but are wispy, flaky, pasty H-shaped objects left behind on objects.

Hemipenis sightings might become more frequent during breeding season. Although an experienced person might evert the hemipenis manually, catching a sight of them just "laying around" on film is nothing short of a challenge! The hemipenis is a pinkish or black-pinkish soft looking cylindrical pair of shapes. Yes, iguana have two!

Hemipenis just coming out of vent.

Hemipenis fully exposed.

Manually everted hemipenis.1

Close-up of manually everted hemipenis.1

Your male iguana might be straining a little with his poop and he will pop out, or just airing himself out or even showing off. He might also choose to masturbate on pillows, towels, and other objects he fancies and leave behind a souvenir. He should right himself shortly, and all will be well. A hemipenal prolapse, on the other hand, is a little more serious and should be taken care of.

Bobbing displays are common to both male and females so it is not a reliable means of determining gender.

PROBING THE IGUANA.

If you aboslutely have to know what the gender of your iguana is, and cannot wait until s/he reveals her/himself to you (no pun intended!), you might have your vet probe. A veterinarian can insert a probe into the cloacal vent down toward the tip of the tail and determine the depths of the "pockets" and thus figure out the gender of the iguana. A female will have shallow pockets; a male will have deeper pockets.

The hemepenis is a lot like a sock or condom. It lays inside the tail (hemipenal bulges) and when the male everts himself, it is a lot like turning the sock or condom inside out through the vent. The females have no such organ, and thus have shallow "pockets."

Although each gender can have it's own particular set of potential gender-related problems (ex: breeding season aggresion in males, egg-binding in females) either gender can make a rewarding pet.

Sources for Adapted Illustrations:

(1) de Vosjoli, Philippe. The General Care and Maintenance of the Green Iguana. 1990. pg. 19

(2) Hatfield, James W. Green Iguana: The Ultimate Owner's Manual by James W. Hatfield III, 1996. page 78