Trying to judge a tarantula’s age is very difficult. Lifespans vary with different species and genders. Male spiders have a much shorter lifespan than females. Males generally live from 3-6 years while females can live 30-40 years. The amount of food eaten and how warm the environment is are factors too.
In order to try and estimate your tarantula’s age, you must first know if it is a male or female. Examine the tarantula in a well lit area. Using a magnifying glass if it’s a small pet will help.
Male spiders have “fusillae” which are short, slightly bent, stiff hairs where the abdomen and legs meet. Female spiders do not have these hairs.
A mature male spider will have large, bulbous pedilaps or fangs. They also have hook-like projections called spurs on the long part of the front legs (tibia).
An immature male spider can be between 2-5 years old. An adult male may be 4-6 years old. Male tarantulas live about 1 1/2 years after they mature.
Determining if a spider is female is much more difficult. Mature females can be two-thirds of full-grown size. Looking at pictures of your particular specie of tarantula can help you determine if it is female.
An immature female can range in age from 2 to 5 years. A mature female can be anywhere from 2 to 40 years old.
The only really accurate way to tell a tarantula’s age is to raise it from birth.