How reliable is it sexing sling/small juve molts?

[Frodo240203]

Is it unreliable to sex 5cm legspan tarantulas both ventrally and by molts? This is because my 2inch legspan GBB looks to be female, ventrally, however the molt shows otherwise. Is it possible that the molt has not developed fully yet?

 

[MissouriArachnophile]

Molt should override ventral, but younger specimens the spermetheca would be lighter in color and may not be as visible. Correct me if I'm wrong.

 

[Minty]

A moult is 100% reliable, for sexing. What isn't reliable, is our ability to see the presence, or lack of, spermetheca when they're at those smaller sizes, without equipment such as a microscope.

In other words, sexing a moult at small sizes can be difficult. I don't bother trying until they're a bit bigger.

 

[Tenebrarius]

checking molts are the most reliable method friend. you would need a microscope for really small molts. so if the molt says different then the ventral then pick what the molt says, cause otherwise it will only be wrong if you had your eyes closed while examining, don't worry it is a simple beginner mistake just make sure to keep them open next time.

 

[Sarkhan42]

With a good dissecting scope I'd be fine sexing as small as 1-1.5" molts, and have done so before with success. Without a scope it becomes MUCH more difficult and unreliable due to how underdeveloped the spermatheca are. It also depends on the species, as some are more distinct and easy to see than others.

 

[Nightstalker47]

Ventral sexing can be very underrated. If you know what to look for, and have experience with that particular species/genus...its pretty much one hundred percent.

 

[korg]

Ventral sexing can be very underrated. If you know what to look for, and have experience with that particular species/genus...its pretty much one hundred percent.

Very true. When you've seen a lot of a certain kind the sex can stick out like a sore thumb.

Generally speaking, though, I would say molt sexing is the usual standard. For non-dwarf species I often don't even attempt that until they're 2"+ (but I don't have a scope) since I kind of figure the sex isn't going to change... no real need to stress over finding out today versus a couple months from now.

 

[Teal]

Is it possible that the molt has not developed fully yet?

Tarantulas are male or female from the start. That won't change with subsequent molts. As others said, the issue with smaller molts is *seeing* the details unless you have the right equipment. 2" molts are about the smallest I attempt with anymore... I always end up tearing any that are smaller

 

[Goopyguy56]

In my experience it depends on the species. I have some with obvious female parts at only one inch. Some I don't see till later. I think the hardest part is getting a sling molt unfolded without tearing it up. Im a science teacher so i have microscopes and all that jazz. You would need some way to magnify the image at sling sizes. I don't have the patience to wait to juvenile sizes so I attempt to sex any molt I can at about 1.5 inches or so. I always make sure to grab their next molt too.

 

[Frodo240203]

Thanks everyone! I will sex its next molt, and if it is truly a male, i’ll make sure I buy a few more GBB slings.

 

[The Grym Reaper]

GBBs are a pain to vent sex (especially at smaller sizes) so I'd say moult sexing would be more reliable in this case.

Generally speaking, at 2" you should be able to sex either way pretty reliably if you know what you're doing.

 

[Vanisher]

If one has a microscope and knows where to look, its not hard to sexing small spiders down to spiderlings

 

[EulersK]

If one has a microscope and knows where to look, its not hard to sexing small spiders down to spiderlings

This about sums it up. By far the biggest determining factor is just unfolding the exuvia without mangling it. Adult specimens can be done with your bare hands, but slings require thin sewing pins and a very steady hand.

A jeweler's microscope works great for anything larger than 2" (5cm). If you want to sex something smaller, you'll need a proper low-powered microscope. I have an endoscope I use, which can reliably sex slings down to 0.5" (1.3cm):



Of course, it is much easier once they get larger than 1":


The actual shape of spermatheca plays a factor as well. The 'alien antenna' style are much easier to catch than the 'flap' style. Here's a few different types (all are adult) so you can see what I'm talking about:

 

[Vanisher]

Exactly! The hardest part is to unfolding such a small and fragil exuvia! If it is dry, soke it in warm water with a drop of dish soap for some minutes!

 

[Vanisher]

A little tip for ya all! that i often use is to unfolding the exuvia and take photographs with my mobileohone (modern phones have good cameras!) I take many pictures snd use a small toothpick to jiggle little where spermatheca is located between photos, hoping to manage to change position on the spermatheca if it is there! I use the flash function ON, on the phone for better picture! Then i can use the zoom to enlarge the picture, and see the spermatheca, or no spermatgeca! This works well down to small juveniles! For slings one has to have a microscope

 

[viper69]

European breeders have been sexing slings at 2" and less for eons. Like anything else, you have to know what to look for. Some NW species are easy to ID than other NWs species.