You can determine if a tarantula is male or female by examining a molted exoskeleton or observing specific physical characteristics on its underside.

To accurately sex a tarantula, inspect the inside of a freshly molted skin for a storage organ called a spermatheca, which indicates a female. You can also perform ventral sexing by looking for an epigastric furrow or epiandrous fusillae on the spider's underside. Mature males also develop unique hooks and bulbous pedipalps.

Ventral Sexing Techniques

Ventral sexing involves looking at the underside of a live tarantula through a clear container. This method is common but requires practice to master. Look for these specific indicators:

• Epigastric Furrow: This is a horizontal slit located between the first pair of book lungs. In females, this area often appears more prominent or slightly lipped.
• Epiandrous Fusillae: Males typically possess a small, dark, triangular patch of specialized silk glands just above the furrow.
• Body Shape: Females generally have a wider abdomen and a sturdier build compared to the leggy appearance of males.

Analyzing the Molted Exoskeleton

Examining a molt is the most reliable way to determine sex. Follow these steps for an accurate result:

1. Wait for the tarantula to finish its molting process and leave the old skin.
2. Carefully remove the skin and soak it in water with a drop of dish soap to make it flexible.
3. Unfold the abdomen area between the four white book lungs.
4. Use a magnifying glass to search for the spermatheca. If you see a small flap or pouch, the tarantula is female.

Comparison of Sexing Methods

Identifying Mature Males

When a male reaches maturity, he undergoes visible physical changes that make identification easy. Mature males develop tibial hooks on their front legs, which are used to restrain the female during mating. Their pedipalps, the small appendages near the mouth, will also become bulbous and resemble boxing gloves.