Is It A Boy or a Girl?

Many people are confused when it comes to guessing the gender of a tarantula, and for good reason- it can be quite difficult at times.  But unless you’re a breeder, why is it so important to determine your spider’s gender? 

Perhaps the number one reason for this is that female tarantulas live five to six times as long as male tarantulas.  Male tarantulas, once they reach maturity, have only another six months to two years to live.  Their sole purpose during this short time is to wander and find mates. 

Female tarantulas are known to reach lifespans of over 30 years for some species.  They tend to be less hyperactive than the males.  Unless you intend to breed tarantulas, you’ll want to stick with females for the most part. 

It is fairly easy to tell an adult female from an adult male, if you know how and are able to take a close look at the spider.  Below is a photograph of the front legs and feelers of an adult male tarantula:

 

 

If you look close, you’ll notice a “hook” on the underside of the first leg.  The males of most species have these once they reach maturity.  These serve the purpose of restraining the female’s fangs during mating.  Please note that immature males do not have these.  So, telling an immature male from an immature female using this method is impossible.

Also look at the feelers (the short appendages near the fangs.)  They end in round “bulbs.”  Here the male has the organs with which he mates.  Mature females and immature tarantulas of both sexes lack these bulbs, but instead have feelers that end in toes that resemble those on the legs. 

But what if your tarantula is not yet mature?  There is another way to tell its gender…but you have to wait for it to molt (shed its skin.)  When it does molt, you’ll need to grab the shed skin while it is still moist.  If you wait until it dries (and sometimes you have to because it’s not reachable) the skin will most likely tear and crinkle when you attempt to examine it.  Note that this method will only work if your tarantula isn’t too young or too small.

Carefully open the shed skin at the abdomen.  There will be four white spots near the top of the abdomen- these are the old linings of the spider’s lungs.  Now look between the two top white spots.  There will be a crease running between them. 

In female tarantulas, mature and otherwise, this crease will have a roundish protrusion sticking up from it.  It may be hard to see in smaller specimens, but using a toothpick to prop it up will help confirm that it’s there.  Here is a photo of the shed skin of my Rose Hair, Fuzzy.  The yellow arrow is pointing at the protrusion that proved I had a female:

 

Now here is the photo of the shed skin of an immature male tarantula.  (Species: Columbian Giant Redleg.)  Note the lack of the telltale protrusion:

 

 

Well, there you have it!  Hopefully you will now be able to tell if your tarantula is a boy or girl.  Be aware, however, that you are always taking a risk when you buy immature tarantulas.  The pet store will rarely know if it’s a boy or girl, unless you’re lucky enough to find one that employs tarantula enthusiasts.  And it’s impossible to tell if you get immature tarantulas using mail-order (something I’ve done.)  All you can do then is cross your fingers and hope for a female (or a male if you intend to breed.)

The Petco where I got Fuzzy told me she was probably a male, due to her skinny abdomen.  Though sometimes accurate, telling a tarantula’s gender by the size of the abdomen (large/round for females, small/skinny for males) is a bit shaky.