Sexing Spoods

With all this space to wander around in, Big Spood has started to walk on the sides of his enclosure, inadvertantly flashing his underparts at me. As he is the biggest of my spoods, and only him and Incy Wincy are really large enough to sex, I have been wondering about Big Spoods gender. Sexing a mature tarantula is much easier, as the two sexes are visually different as adults. But as a growing juvenile, it is harder.

Now, I have already posted these images to two different online resources, and both of them came back to me and told me that Big Spood is most likely a FEMALE, though it's easier to tell once she has molted. Now, if she is a female, then I'm happy, because females can live in the region of twenty years, compared to the paltry four of the male. But how can we tell that Big Spood is a female? To be perfectly honest, I can't tell one from the other, although I have been reading around the subject.

*Side note: Check out those awesome fangs!*

Apparently, the most accurate way to determine a tarantulas sex is through their molts after a shed. Now, my tarantulas either destroy their molts in the process, or they're too small to see anything interesting at this point so this isn't a method I can use (yet!). Obviously, it all comes down to their underparts - all tarantulas have what is called the epigastric furrow - a pouch which houses the entrance to their reproductive tracts, but whilst looking very similar from the outside, male and females differ internally - obviously.

The female epigastric furrow (sometimes called the epigynum) is a pouch which contains two openings. The first is the sperm receptacle, where the male will insert the sperm during mating. The second leads to her oviduct and ovaries. Males have the epigastric furrow, but it lacks the internal pouch. Instead, they have an area of specially developed micro-spinnarets. These spinnarets cover a U shaped area above the epigastric furrow, and serve to spin a special silk which he will infuse with sperm, collect in his pedipalps, and then transfer to the female.

This is why it's often easier to sex an immature spider from the moult - when a tarantula sheds it's skin, it also sheds a lot of the internal structures too. Including the lining of the epigastric furrow. When looking at these molts, a female with have a distinctive flap on the inside, often with two horns or bunny ears. A male will lack this flap.

I guess from looking at these, I can sort of see why they would say Big Spood is a female - she definitely appears to have a 'pouch'. I just felt like maybe she had the patch of micro spinnarets also. That said, I trust their judgement better than mine, so until I am told otherwise, Big Spood is now she/her.