Question on growth rates male vs female

[Gail]

I always thought that the male spiderlings were the ones to grow the fastest but as I was leafing through my copy of Tarantulas and Other Arachnids by Samuel D. Marshall I noticed something that I hadn't before.
Page 19 "Unfortunately, it is tricky to tell the sex of immature tarantulas, as both immature males and females look and act pretty much alike. To maximize your chances of getting an adult female, your best bet is to pick the largest individual of the species that you can find."
This goes against what I thought was true. I thought that in a group of hatchlings up to immature that the females would usually be the smaller. Have I been mistaken in this assumtion? Or is it perhaps only true for certain species. Anyone with more information, please let me know.

Gail

 

[skinheaddave]

If I may paraphrase what he has said in order to illustrate what I think he is trying to get accross:

"Sexing juveniles is imprecise at best and so if you are looking for a mature female, you are best to buy the largest spider of that species you can find as it is much more likely to be mature and can be more reliably sexed at the larger size."

I think his statement is intended for situations where you have a choice of size and not just pick of the litter.

Cheers,
Dave

 

[Garrick]

Perhaps Marshall meant that if you were looking at juveniles or adults, a larger one with a fat chelicerae and abdomen could more than likely be female. Most males mature younger than females and are also smaller when fully grown. For example, if you see fat 4 1/2" A. avic without tibial spurs, I don't think you would need to guess at its gender. If it were male, it would've likely matured before it got to that girth and length.

 

[Botar]

So if the tibial spurs are prominent, does that mean it is mature?

 

[skinheaddave]

Originally posted by Botar
So if the tibial spurs are prominent, does that mean it is mature?

Yes.

Cheers,
Dave