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How do I know a female is adult?

Discussion in 'Tarantula Questions & Discussions' started by boina, Mar 20, 2017.

  1. boina

    boina Arachnosquire Active Member

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    I couldn't find anything about this except some very generalized remarks about size - which is just guess work. Is there any way to reliably tell if a female is adult? I don't want to breed or anything it's just scientific curiosity.

    I already know that adult females only molt once a year or less, but is any T that will only molt once a year already adult? With fast growing species I'd say yes, but my B. smithi only molts once a year and she's only 5" at best - is she adult?

    Are there any other signs?
     
  2. Moakmeister

    Moakmeister Arachnoknight Active Member

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    5 inches is almost the maximum size for a smithi. She's definitely an adult.
     
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  3. EulersK

    EulersK Arachnoengineer Arachnosupporter

    Yeah, she's an adult.

    When we say "adult", we're usually talking about sexual maturity rather than max size. You know that the spider is sexually mature when the spermatheca has scleritized, which you can only see on an exuvia after a molt. This usually happens at roughly 75% max size.
     
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  4. boina

    boina Arachnosquire Active Member

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    Yes, I've been talking about sexual maturity, too, sorry if that wasn't clear, and the B. smithi was only an example, I'm not overly concerned about her being adult or not. I know she's still going to grow since she's only 5 years old, so 75% of max size could be right for her.

    Sooo, these scleritized spermatheca: how are they different from younger spermatheca? I know what a spermatheca looks like in quite a lot of different species, so how do I see whether it's scleritized? Do you know about any pics I could look at? Or can you just describe it?

    And thanks, that information was exactly what I was looking for.
     
  5. EulersK

    EulersK Arachnoengineer Arachnosupporter

    I think she's quite a bit more than 75% size. I wouldn't expect another inch and a half out of her (which is what another 25% would be).

    It's actually quite simple - scleritized spermatheca turns dark, almost black. This is spermatheca of an immature Phlogius - note how it's flesh colored.

    And here is the spermatheca of a mature E. truculentus. The spermatheca is a different shape, but see how it's dark, almost black? That means she's ready to breed.

    Spermatheca are the same shape pretty much regardless of the size of the spider (excluding very young slings). They're always there, it's just a matter of them being usable or not. Very much like the uterus of mammals.
     
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  6. awiec

    awiec Arachnoprince

    I have always described it as even though a 13 year old girl can breed(sexually mature) she is not fully grown usually. Also with spiders it's best to let the female get close to their max size as generally bigger spider=more babies as she has more room and isn't diverting resources away from growing.
     
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  7. boina

    boina Arachnosquire Active Member

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    GREAT pictures!! Now I know! Thank you so much :):joyful::joyful:!!

    (I might have mentioned I'm a biologist, so I do know what a spermatheca is and that it's always there ;))
     
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  8. grayzone

    grayzone Arachnoking Active Member

    Only way to know for sure she is sexually mature is to look at the sceletorization of her spermatheca
     
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  9. Chris LXXIX

    Chris LXXIX Arachnoking Active Member

    With the Goddess 0.1 Pelinobius muticus PBUH (Peace Be Upon Her) yes of course. Nothing transcendental or too complicated, when the rear legs will start to appear she will hiss:
    "Gib mir die Hand Ich bau dir ein Schloss aus Sand Irgendwie irgendwo irgendwann..." :troll:
     
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  10. boina

    boina Arachnosquire Active Member

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    I didn't know you spoke German! And such a fitting quote!
     
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  11. Chris LXXIX

    Chris LXXIX Arachnoking Active Member

    Uhm, ok... I can tell you, Lady, but please 'Psssht!' keep the secret :)

    The reason why I speak German is because I worked as a waiter back then into a central Italy Hotel. When Angela Merkel loved to visit that area of Italy, while Joachim Sauer was outside for taste the Italian delicatessen recipes, I was forced by the Chancellor to perform not so 'wunderbar' Sociology/Sexual games:
    she was the rich ice cold EU Dominatrix. Me, forced to act as the ignorant and poor DDR worker that never saw a BMW car in his entire life.

    I've learned German the bad way, oh poooor me... oh poor Chris :-(

    This is the truth, nonetheless :troll:

    A lie is that here, in Northern Italy, German was after English the second language teached in higher education schools but my German, actually, sucks a lot, ah ah :)
     
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  12. viper69

    viper69 ArachnoGod Old Timer

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    How big do you think this species gets??
     
  13. boina

    boina Arachnosquire Active Member

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    From what I've personally seen they can get 6.5" - at least some of them.
     
  14. darkness975

    darkness975 Dream Reaper Arachnosupporter

    Ich hab' das interessant gefunden ...

    I am not sure how common that size is but I have seen some impressive specimens in the past. There was one YouTube video I found recently of a "massive XXL spider" B. smithi. Hard to tell with the actual size was though, especially because the person was handling it and allowed it to bolt almost getting away on the floor. :banghead:
     
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  15. grayzone

    grayzone Arachnoking Active Member

    You can always ask to see her ID
     
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  16. viper69

    viper69 ArachnoGod Old Timer

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    I'd have to see it to believe it myself, that would be pretty exceptional IMO.