Theory - looking for anecdotal evidence

[waynerowley]

We all know that the only way to be certain on the gender of a T is to check the moult. This requires an intact moult of sufficient size. We also see that many mature males are what we would class as 'leggy' (longer leg to body ratio, smaller bodies etc.).

While rearing my slings I have noted that - even from a small size - some are growing up quite chunky (small leg to body ration) while others are leggy. Is it likely that the leggy spiders will eventually prove to be males and the chunky ones female?

Just curious.

Wayne

 

[8 legged]

Especially with species like Psalmopoeus and / or Tapinauchenius you can be totally wrong...
I wouldn't count on it. With the right experience and the right tools, you can gender (the molt) with the fourth instar...

 

[waynerowley]

Especially with species like Psalmopoeus and / or Tapinauchenius you can be totally wrong...
I wouldn't count on it. With the right experience and the right tools, you can gender (the molt) with the fourth instar...

Yeah - I can see myself buying a digital microscope - my phone camera doesn't cut it!

 

[8 legged]

Google "euromex stereoblue"...

 

[viper69]

We all know that the only way to be certain on the gender of a T is to check the moult. This requires an intact moult of sufficient size. We also see that many mature males are what we would class as 'leggy' (longer leg to body ratio, smaller bodies etc.).

While rearing my slings I have noted that - even from a small size - some are growing up quite chunky (small leg to body ration) while others are leggy. Is it likely that the leggy spiders will eventually prove to be males and the chunky ones female?

Just curious.

Wayne

No not always IME

Also some species do not require molt confirmation. Versi is one.

 

[waynerowley]

Also some species do not require molt confirmation. Versi is one.

But only once they reach a certain size and maturity? I tried to sex 'Flo' my versicolor ventrally several times from about 2 inches. Response was nearly 100% 'male'. Sexing from a larger moult though showed her to be female.

Wayne

 

[viper69]

But only once they reach a certain size and maturity? I tried to sex 'Flo' my versicolor ventrally several times from about 2 inches. Response was nearly 100% 'male'. Sexing from a larger moult though showed her to be female.

Wayne

For versi at 3” IME, maybe 2.5”, you look at the vent. Females have a white upper lip. If I can see that anyone can.

 

[PidderPeets]

I do think there is instances where general appearance can reflect the sex of the spider. However, I don't think it's anywhere near accurate enough to even make an estimate at the sex.

I've raised multiples of a handful of different species, and sometimes the proportions correlate to the sex, but oftentimes they don't. I've also had an instance of a mature female A. avic that after a molt could have fooled anyone into thinking she was a mature male because of her gangly appearance. There's just too many variables to sex a tarantula from general appearance (mature males being an exception).

Molt sexing is obviously the most accurate method, but many species can be easily sexed ventrally as well. It just requires some practice

 

[spideyspinneret78]

Not necessarily. In my opinion there's too much individual variation, and a lot of it depends on where the sling/ juvenile is in its molt cycle.

 

[Smotzer]

I would not use your above mentioned theory

 

[waynerowley]

I would not use your above mentioned theory

Who says I’m planning to use it for anything? I’m curious thats all. People have been keeping Ts longer than I have and may or may not have noticed the same.

I’ll sex the spiders once I get can hold of a suitable moult.

 

[waynerowley]

For versi at 3” IME, maybe 2.5”, you look at the vent. Females have a white upper lip. If I can see that anyone can.

I found on Flo it wasn’t really obviously a white lip until she was approaching 4”.

 

[Smotzer]

Who says I’m planning to use it for anything? I’m curious thats all. People have been keeping Ts longer than I have and may or may not have noticed the same.

I’ll sex the spiders once I get can hold of a suitable moult.

I don’t think I implied that, I meant I would not use that because I have not found it to mean anything other than natural variation, the same goes for growth rate/and size during sling stages.

 

[waynerowley]

I don’t think I implied that, I meant I would not use that because I have not found it to mean anything other than natural variation, the same goes for growth rate/and size during sling stages.

Understood. I’m sure that if it was as simple as this then people would have been able to sex spiders as slings long ago. It is interesting though how they differ.

 

[viper69]

Who says I’m planning to use it for anything

@Smotzer reply spoke only of his own behavior, and nothing about your intentions etc. That’s a big reach

 

[Smotzer]

@Smotzer reply spoke only of his own behavior, and nothing about your intentions etc. That’s a big reach

Exactly only about me friends

 

[waynerowley]

Exactly only about me friends

I realised that when you followed up - I misunderstood your post. Sorry about that.

Wayne

 

[The Grym Reaper]

Is it likely that the leggy spiders will eventually prove to be males and the chunky ones female?

Nope, the whole "skinny leggy males vs chunky females" thing only really applies to mature specimens. I've raised sac mates of both sexes that have basically been outwardly identical when viewed dorsally, the only way you could tell them apart without a moult was by ventral sexing.

Some species are naturally leggy and slender bodied and this is further exacerbated by a moult, I posted a pic of my freshly moulted female G. iheringi on IG a few years back and a bunch of people in the comments were adamant she was male based solely on how skinny and leggy she was, I ended up posting a pic of the spermathecae to prove them all wrong.

 

[darkness975]

I've had specimens that I was fairly confident were female end up male. Usually to my disappointment.

Same thing happens with Araneomorphae I keep (widows, etc). I recently had an L. hesperus that I was hoping was female molt out as a MM.

 

[Wolfram1]

I always wonder if they even have longer legs at all. We all know that under the right conditions our brains can be tricked into thinking one line is twice the size of another one right next to it, despite them beeing identical.

(for example the müller-lyer illusion)

I imagine the positioning of the legs could trick us into thinking one had longer legs than another individual and once we have that stuck in our heads we always see it.


Mature males, sure, but all the rest? I dont think so. Has anyone ever measured the leg segments of male and female, juvenile specimens of the same body-lenght and compared them? Same sp. obviously.