How to Tell If a Tarantula Is Male or Female

Determining the sex of a tarantula can be challenging. Many young tarantulas look the same until they go through one molt and, in some cases, it is impossible to tell the sex until the male is mature. But by looking at certain areas of the tarantula body, you can usually determine the sex of your spider successfully.

Things You'll Need

  • Pocket microscope
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Instructions

    • 1

      Look at the underside of your tarantula. Male tarantulas have an extra set of fusillae and glands for spinning silk connected to their epiandrous glands. These glands manufacture a special silk for the sperm web. You can see this with the naked eye, but it's easier if you use a pocket microscope with good lighting. When using a microscope, press it lightly against the spider's belly.

    • 2

      Look at your spider's molt (the inside of the abdomen). A female tarantula will shed her spremathecae lining when she sheds her exoskeleton. This is a delicate process and should be done by someone with experience, as it requires softening the skin and unfolding abdominal skin. A microscope is helpful, but it is possible to see the lining with the trained naked eye.

    • 3

      Look at your tarantula's pedipalps (the second pair of walking legs). A mature male will have bulbs on the ends of them. Some species have tibial hooks on the underside of the tibia (long segment) on the first pair of the spider's walking legs.

    • 4

      Look at your spider's chelicerae (parts of the mouth). Females will have larger and wider mouths than males, who have thin mouths. On a female, this area may look swollen, but in a male it is uniform.

    • 5

      Look at the size of your spider. Generally, female tarantulas are larger than males. Their jaws are often broader than a male's jaws. These differences are subtle, however, and may not be discernable to an inexperienced eye, according to Tarantulas.com.