Updated: May 9, 2022 by Jennifer Munsell
Male vs female iguanas — how do you know your pet’s sex?
Fortunately, it’s actually fairly easy to learn how to sex an iguana, as they are sexually dimorphic. This means there are several key physical differences between the males and females of the species. However, this does mean you’ll need to wait until your iguana is sexually mature in order to definitively tell whether it is a male or a female.
Green iguanas, the most common species kept as pets, reach sexual maturity between 1 and 4 years of age. If you need to know the difference even sooner, you can take your iguana to your exotic veterinarian for them to do an examination and determine whether your iggy has hemipenes or not.
Otherwise, read on to learn more about sexing iguanas!
Main Differences Between Male vs Female Iguanas
The main differences between male and female iguanas are:
- Male iguanas are much heavier, whereas female iguanas are lighter than males.
- Male iguanas have huge jowls and a pronounced dewlap, whereas females have small jowls and a barely present dewlap.
- Male iguanas have large femoral pores and hemipenal bulges, whereas female iguanas do not have enlarged femoral pores or hemipenes.
- Male iguanas do not lay eggs, whereas female iguanas will lay eggs even if they have not mated.
- Male iguanas have large dorsal and vertebral spikes, whereas females’ spikes are much smaller and less pronounced.
If you’re wondering whether you should adopt a male or female iguana, neither sex is significantly better or worse to own in terms of temperament or ability. Whether you should have a male or a female iguana will mostly come down to the amount of space you have available and how many other iguanas you have.
Males are much larger than females and will require a larger enclosure. The entire enclosure will need to be higher, longer, and wider to house a male. However, females will need to have a burrowing box or section of their enclosure which they can dig in and not be able to escape.
It is important to know how to tell the difference between male and female iguanas so you can prepare your iggy’s enclosure appropriately for the future.
Read on to find out exactly how to tell the difference between male and female iguanas.
How to Sex Your Iguana
Once you understand all of the different and distinct features that male iguanas have, it is quite simple to identify females because they simply lack all of these attributes. Remember that these features will only become apparent once your iggy has reached sexual maturity.
Male iguanas can get up to eight feet in length and can weigh over 20 pounds! However, female iguanas will rarely exceed six feet in length and typically max out at around 6 to 10 pounds.
The first difference you’ll probably notice is that males have much broader and heavier bodies with thicker, more powerful tails. Females, on the other hand, have much slimmer, narrower bodies and have thinner, more whip-like tails.
In addition to this, male iguanas have very broad and powerful chests, which means they also stand taller than the females.
Below are approximate growth charts for male and female iguanas. You can see that during their early years, male and female growth is pretty much the same. During their first couple of years of life, they are not yet fully sexually mature, which means the more obvious size and feature differences have not yet appeared.
Keep in mind that the lengths listed are measured from the iguana’s snout to tail tip.
Male Iguana Growth Rate
However, once green iguanas become sexually mature, there is a very distinct size difference both in length and in weight.
Female Iguana Growth Rate
Head Shape, Size, and Features
Aside from their weight and length, male and female green iguanas have several differences when it comes to the shape and size of their heads. Below I’ve listed the most obvious differences between the two sexes.
Male iguanas have small bumps on top of their heads just behind their eyes. These bumps become more pronounced the older the iguana gets.
These bumps are missing on female iguanas. The lack of these bumps makes the female iguana’s head look much slimmer and smoother than those of the males.
Male iguanas have very large dewlaps under their chins. These dewlaps are large flaps of skin that are meant to look scary and impressive and set alpha males apart from the rest. Male iguanas with the largest dewlaps typically attract more females during mating season.
Female iguanas, on the other hand, have very small dewlaps. Sometimes, these dewlaps are not even present, particularly on very small or young females.
Male iguanas have very powerful jaws. Their jaws get their power from the incredibly large muscles on either side of their face. These very large muscles make it look like the males have huge, bulging jowls.
On the other hand, females do not have facial muscles that are quite as large as the males’. This also means their ‘jowls’ are not nearly as large and that a female iggy’s bite will not be as painful or damaging as a male’s.
Both male and female iguanas have enlarged disk-like scales on either side of their heads.
Male iguanas’ disks are typically much larger than the females’ and will be darker in color or have a green, almost black ring around them.
Female iguanas also have these enlarged disk-like scales on either side of their heads. However, these disks are smaller and not deeply colored or ringed in a dark green/black color.
Another key difference between males and females is the size of their spikes.
Male iguanas have elongated dorsal spikes that run along their spines. These spikes will start at the tip of their tail and run all the way up to their heads. Males will have smaller spikes along their chins, too! A male iggy’s spikes are very tough, long, and distinct.
Female iguanas do have dorsal spikes that run along their spines; however, these spikes are much smaller than the males’ ones. In general, they are shorter, thinner, and softer. The female’s spikes run from the tip of their tails to the base of their necks. Females do not typically have spikes on the tops of their heads. They do, however, occasionally have short spikes under their chins.
Juvenile iguanas will have soft dorsal spikes from a very young age, so using their spikes to determine sex is not reliable until they are about 3 to 4 years old.
Another key difference between sexually mature male and female iguanas is their genitals. Below are the two main differences that become apparent once a green iguana reaches adulthood.
Male iguanas have distinct femoral pores. These look like large, pale scales on the inside of their thighs on their hind limbs. The femoral pores enlarge during mating season and secrete a waxy substance that contains pheromones that attract potential female mates.
Female iguanas, as you’d imagine, do not have pronounced femoral pores. This is simply because they do not have a need for them. When looking at the hind limbs of a sexually mature iguana, it is very easy to see the difference between males and females.
At the base of a male iguana’s tail where it meets the lizard’s body, there are two distinct bulges. These bulges contain the hemipenes. As a reptile with a tail, iguanas have two penises to facilitate sexual reproduction.
Females do not have these bulges because they do not have hemipenes.
Do not probe the cloaca to determine the sex as you would a snake. If you are not an expert at “expressing” an iguana’s hemipenes, you can severely injure your animal and stress them out significantly.
However, if you want or need to know what sex your iguana is before they are sexually mature and the seller is unable to tell you, then take your iguana to an exotic veterinarian to get them to determine the sex.
Another fairly obvious difference between male and female iguanas is that females lay eggs. Male iguanas do not lay eggs at all. If your iguana suddenly lays an egg or two, you can be assured it is a female.
Notably, female iguanas will occasionally develop and lay eggs without ever coming into contact with a male. This is just part of their natural cycle. They will also exhibit burrowing and nesting behavior during laying times.
This means that, in terms of husbandry, females will need a section of their enclosure that is safe to dig in.
It is also worth mentioning that developing and laying eggs uses up a huge amount of energy. Female iguanas will use their energy reserves to produce eggs over maintaining their own bodies. This is one reason why females do not always live as long as males.
This also means that female iguanas will need a larger amount of calcium in their diet to ward off metabolic bone disease. They can get this calcium in the form of a calcium supplement that should be added to their daily salad.
Sex-Specific Health Problems
Male and female iguanas can both suffer from malnutrition, a lack of UVB lighting (vitamin D absorption), and metabolic bone disease. These are all things that can be rectified through their diet and an adjustment of their enclosure settings.
In addition, both male and female iguanas can suffer from internal and external parasites. This is usually the case when your iguana is wild-caught or is farm-raised. A simple trip to the vet can help rectify parasite problems.
There is, however, one health condition that affects female iguanas and not males: that is becoming egg bound, also known as dystocia. If for some reason a female is unable to lay an egg, it will become stuck inside of her.
Being egg-bound is incredibly painful for an iguana to endure. It can lead to decreased fertility in the future and even death if not treated promptly.
Iguanas affected by dystocia need urgent vet attention to resolve the problem. A female iguana becoming egg-bound is very rare. However, if it does happen, it is usually because something is wrong with her care. For example, she might be dehydrated or too cold, not have enough space to exercise and move, or not have a proper nesting box.
Be sure to follow your reptile vet’s instructions in order to solve the issue. In mild cases, fixing what is wrong with the husbandry will resolve the problem very quickly. In more severe cases, the female iguana will need to undergo surgery to get the stuck egg removed.
Final Thoughts on Sexing Iguanas
Which sex is better to own: a male or a female? Well, neither sex is objectively better to own, as they are pretty much the same animal in every way except looks and a few small husbandry differences.
Males and females mostly share the same kind of temperament. Both sexes can be very aggressive if they are not socialized properly from a young age. However, both sexes can also make lovely companions if their care is high-quality and consistent from the time they are hatchlings.
Males are much larger than females and will need larger enclosures, more food, and a stronger set of hands to wrangle when they are in a bad mood.
Females, on the other hand, are smaller, they require less enclosure space, and you can house multiple females together.
The real decision comes down to your preferences and capabilities as a reptile owner.
FAQs About Male and Female Iguanas
Can I keep multiple female iguanas in the same enclosure?
You can keep multiple female iguanas in the same enclosure. If you are aiming to have an enclosure with multiple females, try and get them all at the same time and at the same age. This will ensure there will not be a new addition to the family that is more dominant than the others.
Always remember that when you add another iguana to an enclosure, you need to increase the size of the enclosure, the amount of vertical climbing space, and the number of water dishes, hides, and basking spots.
Can I keep multiple male iguanas in the same enclosure?
You should not keep multiple male iguanas in the same enclosure. They become territorial and aggressive during mating season and will end up fighting each other (in many cases to the death).
If you feel like adding another iguana to your established male’s enclosure, look for a female around the same age.
Like with female iguanas, always remember that when you add another iguana to an enclosure, you need to increase the size of the enclosure, the amount of vertical climbing space, the number of water dishes, hides, and basking spots.
Are male or female iguanas more aggressive?
Neither sex is more aggressive than the other if they are in the right enclosure and are kept using proper husbandry techniques.
However, males will temporarily become more territorial and aggressive during mating season, especially if there are other males present. This is natural, as in the wild, they need to be more dominant and aggressive than other nearby males so they can mate with all the females without competition.
Females can occasionally be aggressive if they are defending their eggs or their nesting box. In the end, your iguana’s level of aggression comes down to the amount of socializing you have done rather than what sex they are.
Can I pop the hemipenes out to determine sex as you do with snakes?
You should never attempt to ‘pop’ or ‘express’ the hemipenes out of any lizard, including iguanas. This can cause permanent damage to your iguana and also be incredibly painful for them.
Do male or female iguanas live longer?
Male and female iguanas live to be approximately 10 years old in the wild. In captivity, however, they can live for around 20 years with high-quality care! Their lifespans are not sex dependent.
However, if females are not given proper calcium supplementation during their egg laying times, then their life spans can be shortened. Additionally, if males are housed together with other males and they are subjected to large amounts of consistent stress, then their life spans will be shortened.
Iguanas are fantastic reptiles to own regardless of their sex. However, knowing the differences between male and female iguanas will help you plan the long-term care requirements for your pet.
Knowing how to tell if an iguana is malke or female is fairly simple because they have such distinct physical differences once they are sexually mature. Always make sure to check in with your veterinarian if you are unsure of the sex.