Ventral sexing - guessing or knowing?

[boina]

Ventral sexing, also called epiandrous fusillae sexing, is generally considered not as reliable as molt sexing. I think it is, though. I sex all my spiders from ventral and by now I'd think I can see as clearly as in a molt what sex a spider is. But: I need a good, clear look or a good, clear pic.

There is a problem with that, though: The pictures that get posted in this really great sexing gallery are usually blurry, too far away, have a bad angle, bad lighing or a combination of any of these factors. Still, people guess away and often claim to be absolutely sure of their guesses, even in cases when I think it's impossible to decide anything from the pic in question. In other cases people post unrecognizable pics and are upset when they don't get any answers.

So, I want to make a test. You'll find two rather bad pics, both of Poecilotheria subfusca lowland 4" juveniles (I've 6 of those to chose from). Poecilotherias are generally considered very easy to vent sex, so would you do me the favor and guess what sexes these spiders are? I know the sex, of course, I just want to prove a point here.

 

[Venom1080]

vent sexing is definitely accurate. but it totally depends on the person vent sexing. many groups on facebook dont allow vet sexing photos as morons tend to argue in large numbers over them. everyones an expert vent sexer. Its much much easier in person. When you are able to look from any angle you want with a flashlight.

 

[Theneil]

For the record i am terrible at vent sexing. Some brachys i am pretty confident when i see the dark circle patch, but beyond that i usually am quite uncertain.

That said, i will be happy to play along. with the guessing game. Only a 25% chance of being 100% wrong, right?

Top female bottom male. I see the bald 'line' of the epigastric furrow which usually i see people identify with female, but i also see a faint, light circle/dot so i will guess male.

 

[boina]

For the record i am terrible at vent sexing. Some brachys i am pretty confident when i see the dark circle patch, but beyond that i usually am quite uncertain.

That said, i will be happy to play along. with the guessing game. Only a 25% chance of being 100% wrong, right?

Top female bottom male. I see the bald 'line' of the epigastric furrow which usually i see people identify with female, but i also see a faint, light circle/dot so i will guess male.

Thanks for playing .

 

[Hardus nameous]

As Theneil said, I'm no expert either, but I would guess the top is male and the bottom is female.

 

[The Grym Reaper]

I guessed 1M/2F.

Tbh, I find it much easier in person but it also depends on the species. I suck at vent sexing Avics but I could probably spot the gonoslit of an Acanthoscurria female from a mile off after being pepper-sprayed.

 

[Rigor Mortis]

I guessed 1M/2F.

Tbh, I find it much easier in person but it also depends on the species. I suck at vent sexing Avics but I could probably spot the gonoslit of an Acanthoscurria female from a mile off after being pepper-sprayed.

You sure do have a way with words, Grym.

 

[The Grym Reaper]

You sure do have a way with words, Grym.

I get told that a lot

 

[cold blood]

First male, second female.

I concur that many times, vent sexing can be completely accurate, depending on the species, quality of pic and experience of the person doing the sexing.

 

[Greasylake]

I don't chime in on vent sexing photos, because half the time I look at them and i would just be guessing. I've used it in person and so far I've been spot on, but pictures are just too hard for me.

 

[Liquifin]

I don't chime in on vent sexing photos, because half the time I look at them and i would just be guessing. I've used it in person and so far I've been spot on, but pictures are just too hard for me.

Pictures are easy to vent if people didn't use potato operated cameras.

 

[boina]

Its much much easier in person. When you are able to look from any angle you want with a flashlight.

Top female bottom male.

top is male and the bottom is female.

I guessed 1M/2F.

First male, second female.

I don't chime in on vent sexing photos,

Pictures are easy to vent

Ok, let me clear this up before I go to bed.

- If you haven't voted don't read this but vote first, please -




These two pics are actually of the same spider and she's female. Yes, the top pic is from a female. I played with lighting a bit and realized I could make her look male if I shone the flashlight at just the right angle and took the pic just a little out of focus. And that's what I wanted to demonstrate: Even experienced people get it wrong if the only have a bad pic to work with. So, think again before you commit to identifying a specific sex from a bad pic. - I know this was just a guessing game and the experienced people would probably not have claimed male if a pic like that would show up in the sexing gallery.

 

[The Grym Reaper]

I played with lighting a bit and realized I could make her look male if I shone the flashlight at just the right angle and took the pic just a little out of focus.

So, you deliberately misled me? I'm not angry... Just disappointed

 

[MetalMan2004]

You certainly proved a good point. It’s extremely hard to take good vent pics, so people tend to use what they can get. I’ve spent 20-30 minutes before trying to get lighting correct and the spider in the right position, only to give up.

It’s almost impossible to get a good picture without a secondary light source besides the flash, given the reflectivity of acrylic and glass. Then if the tarantula doesn’t want to cooperate it can sometimes be plain impossible to get a picture good enough to accurately use.

 

[boina]

So, you deliberately misled me? I'm not angry... Just disappointed

Cookie as peace offering...

 

[antinous]

Cookie as peace offering...

I prefer beer myself tbh

I actually did something similar as a ‘private’ experience for myself on a FB group I’m part of. Mind you I can’t sec a T centrally for the life of me and I’m pretty new at sexing in general. Anyways, I posted two photos of the same T at two different angles and got different answers for each photo from people who claimed to be ‘proficient’ at sexing T’s. Didn’t tell them that tho, I feel that people on the groups would jump on me.

 

[Minty]

I don't consider myself to be particularly good with ventral sexing, especially in photos. I thought the first photo was a male and the second photo was a female. Given that the opening post said boina was trying to prove a point, I thought both were going to turn out to be female, but I was honest with my poll answer as the first picture did look male, to me.

 

[AphonopelmaTX]

Ventral sexing, also called epiandrous fusillae sexing, is generally considered not as reliable as molt sexing.

I hope you don't think I'm picking on you by correcting some of the terminology in your posts. I am not and I actually like how you elaborate on some of these topics in tarantula husbandry.

Ventral sexing and sexing by looking for the epiandrous fusillae are not the same thing. When people use the term "ventral sexing" they are usually looking at the epigastric furrow for a raised or swollen epigynal plate in females in which one can see unsclerotized tissue (the white or pale blue area in the epigastric furrow). If the top of the epigastic furrow is raised it is female; if the epigastric furrow is smooth or nearly indistinguishable, then male. This is most noticeable in your second picture. This can be a reliable means of sexing a tarantula but only in large immatures and also it isn't consistent across taxa. Like looking for the epiandrous fusillae, this develops over time as a tarantula grows. So both methods of sexing by external examination can never ever be reliably done in small spiderlings.

I bet you a hundred euros that people who said the top picture is male and the bottom picture is female were basing their analysis on the presence or absence of the white strip of tissue between the anterior book lungs and not by seeing epiandrous fusillae in the top picture.

 

[Venom1080]

I hope you don't think I'm picking on you by correcting some of the terminology in your posts. I am not and I actually like how you elaborate on some of these topics in tarantula husbandry.

Ventral sexing and sexing by looking for the epiandrous fusillae are not the same thing. When people use the term "ventral sexing" they are usually looking at the epigastric furrow for a raised or swollen epigynal plate in females in which one can see unsclerotized tissue (the white or pale blue area in the epigastric furrow). If the top of the epigastic furrow is raised it is female; if the epigastric furrow is smooth or nearly indistinguishable, then male. This is most noticeable in your second picture. This can be a reliable means of sexing a tarantula but only in large immatures and also it isn't consistent across taxa. Like looking for the epiandrous fusillae, this develops over time as a tarantula grows. So both methods of sexing by external examination can never ever be reliably done in small spiderlings.

I bet you a hundred euros that people who said the top picture is male and the bottom picture is female were basing their analysis on the presence or absence of the white strip of tissue between the anterior book lungs and not by seeing epiandrous fusillae in the top picture.

I swear I've had female Poecilotheria with a flat line. Good info though.

 

[Theneil]

These two pics are actually of the same spider and she's female. Yes, the top pic is from a female. I played with lighting a bit and realized I could make her look male if I shone the flashlight at just the right angle and took the pic just a little out of focus. And that's what I wanted to demonstrate: Even experienced people get it wrong if the only have a bad pic to work with. So, think again before you commit to identifying a specific sex from a bad pic. - I know this was just a guessing game and the experienced people would probably not have claimed male if a pic like that would show up in the sexing gallery.

i knew it all along! I meant female for both, stupid auto correct on my phone messed it up...