stylistic:tone, information:extraction
Sexual dimorphism

Some tarantula species exhibit pronounced sexual dimorphism. Males tend to be smaller (especially their abdomens, which can appear quite narrow) and may be dull in color when compared to their female counterparts, as in the species Haplopelma lividum. Mature male tarantulas also may have tibial hooks on their front legs, which are used to restrain the female's fangs during copulation. Males typically have longer legs than the females.

A juvenile male's sex can be determined by looking at a cast exuvia for epiandrous fusillae or spermathecae. Females possess spermathecae, except for the species Sickius longibulbi and Encyocratella olivacea. Males have much shorter lifespans than females because they die relatively soon after maturing. Few live long enough for a postultimate molt, which is unlikely in natural habitats because they are vulnerable to predation, but has happened in captivity, though rarely. Most males do not live through this molt, as they tend to get their emboli, mature male sexual organs on pedipalps, stuck in the molt. Most tarantula fanciers regard females as more desirable as pets due to their much longer lifespans. Wild-caught tarantulas are often mature males because they wander out in the open and are more likely to be caught.