How do I know what gender my pet tarantula is?

It’s very easy to determine the gender of a cat, dog or other mammal commonly kept as a pet. However, arachnids don’t have discernible external markers that clearly determine their gender.

It takes a bit more detective work to find out what the sex of your tarantula is. Here’s a hint: you’ll need to keep your spider’s molted exoskeleton!

What traits can I use to help identify the gender of my tarantula?

While it’s really only useful to very experienced tarantula keepers, it is possible to examine the underside of a tarantula’s abdomen to help assess gender. However, this requires very good eyesight, a lot of experience and a calm spider that will allow you to turn it over without stress or retaliation.

It’s also necessary to have a spider with a leg span of at least two inches. We do not advise using this method to determine spider gender for those reasons.

If you have a fully mature tarantula, you can also use identifying traits that only males possess to help determine gender. For instance, most male tarantulas develop what are known as “boxing gloves” and tibial hooks on their legs.

They will also be longer and lankier-looking in appearance than females. Again, we’d like to mention that these traits take time and experience to recognize and are not usually a good method of determine gender for most owners.

Size is another trait that can be used when you are looking at a mature tarantula. Females tend to be larger and they also live much longer than males. This makes them quite prized in the hobbyist community. However, this trait is not helpful when you are dealing with juvenile spiders that have not undergone many molts.

How do I use my tarantula’s molted exoskeleton to determine its gender?

Be aware that in tact molts can be a little hard to acquire. As soon as your spider has finished molting, you will want to secure the molt while it is still semi-pliable. If you allow the molt to dry out for too long, it can crumble when you try to look more closely at it.

Once you have your molt handy, you need to look between the first set of book lungs or respiratory organs. Female spiders will have a spermathecae, which is a special organ where the female stores sperm until she is ready to lay eggs. Males lack this organ and the molt will appear smooth in this area.

Not all spermathecae look the same in different spider species. For most species, it looks like a flap or small protrusions. Again, you will know you have a male spider if it is flat and smooth in the area between the book lungs.

Be mindful that examining a tarantula’s molt is the only tried and true method to determine gender accurately and without fail. You can most certainly use other indicators to make educated guesses, however molts are the best way to know whether or not you have a male or female spider.

When is my tarantula old enough to find out its gender?

There is currently no known and reliable method to determine the gender of a baby tarantula or spiderling. Not only are they very hard to keep still, they are even tougher to visually examine closely enough to make any type of assessment.

Spiderlings have also not fully developed their sex organs yet, so more molts are necessary before you can examine either the spider itself or its exoskeletons for traits to determine gender.

Usually, you can begin to determine the gender of the spider when you notice that it is large enough to leave behind a fully intact molt. In order to accurately find out if your spider is male or female, you will need to look at and handle the molt very closely. So the larger the molt, in theory, the easier you can determine gender.

Conclusion

Unfortunately, you can’t find out the gender of your pet tarantula by turning it upside down and examining its abdomen. Spiders that are commonly kept as pets simply don’t possess traits that would easily identify them as male or female the way that most mammals do.

In order to find out whether your tarantula is a boy or a girl, you will need to wait until the spider has matured a bit. You will also need to keep a shed exoskeleton so that you can examine it closely.

So, unless you already know the gender of your spider, we highly recommend giving it a gender neutral name!

You can view the wonderful list of tarantulas we have for sale by clicking this link.