Although there are more than 900 species of tarantula, they all share certain physical characteristics that help people distinguish males from females. An observer may sex a tarantula -- that is, determine whether the tarantula is male or female -- by noting, in part, the spider's size, color scheme and molting patterns.
Females tend to be larger than males. They also have larger abdomens than males for reproductive purposes.
Mature male tarantulas have hooks on their front legs. They use these hooks to restrain a female’s fangs during the mating process. Spiders are venomous, so the hooks prevent the ladies from sinking their fangs into them and killing them in the middle of copulation.
Speaking of dangerous odds, males tend to have very short life spans. Therefore, if a tarantula molts again after reaching sexual maturity, odds are it's female. A tarantula’s molted skin is called the exuvium. A female’s exuvium has a spermathecae -- or a sac for sperm storage -- in the portion that covers her abdomen.
Male tarantulas have an extra set of silk-spinning glands called epiandrous fusillade. They use this extra set of glands to create a sperm web.
Females are the ones that have to attract the males when it comes to mating. Therefore, they tend to have red or orange spots across their backs and abdomens. Males are dull colored, tending to be gray, black or brown.
- Tom Brakefield/Stockbyte/Getty Images