Sexing Information


Most (but not all) male Tarantulas acquire "tibial hooks" upon completion of their ultimate molt in life. These are small hook-like protrusions on the tibial portion of both front legs and are used to "lock up" with the females fangs to better position her during mating.	All Mature male Tarantulas will acquire some form of "palpal bulbs" after completing their last or "ultimate" molt in life. Located on the ends of each front "feeler", they are highly specialized sex organs used in the mating process to transfer the sperm to the females genitalia.

Sperm Web Construction

As you can see in this photo, a mature male Tarantula has
constructed a "sperm web" and by carefully looking you can spot a drop of sperm with the palpal bulb extended inside of the sperm droplet.

A visual guide to locating the female Spermatheca
by examination of an excuvia (molt or shed skin)

Locating the epiandrous fusillae on an immature male Tarantula or
the lack of on a female Tarantula. Please know that most species
will NOT have epiandrous fusillae that is clearly visibly with the
naked eye and will require magnification and experience in examining
a number of specimens. The epiandrous fusillae are basically a shorter,
and more dense patch of shaped hairs that have a specialized purpose
in the construction of the male's sperm web. It does not always appear
as a dark spot, and in some species may appear even lighter colored or to the naked eye, no visible difference. The point here is to look at as many specimens, of as many species as you can and you will begin to see the differences. In many species you will not be looking for color, but under magnification, the size, shape and specific distribution of these hairs.

Brachypelma albopilosum Curlyhair

A Female B. albopilosum (The Spermatheca is clearly present)	A Female B. albopilosum. (Lack of epiandrous fusillae)	An immature Male B. albopilosum (The epiandrous fusillae is present)

Brachypelma smithi Mexican Redknee

A Female B. smithi	A Female B. smithi	An immature male B. smithi

Aphonopelma moderatum

A Female A. moderatum	A Female A. moderatum	An immature male A. moderatum