This business with the odds of getting one gender or the other...

Tim Benzedrine

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It only applies if you get multiples of the same species, correct? in other words, if you get six of all different species, your odds don't improve from around 50/50 for each sling, right? For the purpose of this question, say that all sacs are created equal.
 

awiec

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It only applies if you get multiples of the same species, correct? in other words, if you get six of all different species, your odds don't improve from around 50/50 for each sling, right? For the purpose of this question, say that all sacs are created equal.
Its hard to put a number down just due to the fact that some species historically are biased for one gender (p.muticus males are pretty uncommon) so I would say 3 minimum will get you what you want in species that are more 50/50 but 5 is even better. At certain point there is no increase in your ratio odds so I think buying more than 10 is unnecessary
 

Sam_Peanuts

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Correct, your odds of getting one gender of the specific species won't increase, but your global odds of getting a specific gender will increase.

Assuming a 50/50 rate of production, you still only have a 50% chance for all six species(so no, it doesn't improve for each sling), but you'll have 98.4375% chances of having at least one of the gender you wan in the whole lot, you just don't know for which species it will happen.


There's always an increase in the odds the more you take but at a certain point, the increase is pretty much negligible. At 5 you already have almost 97%(96.875%) chances of getting at least one of which ever you want which is good enough unless you're extremely unlucky.


To calculate the odds, you just have to halve in two the increase you get from the last amount you had and add it to the total of the previous chances you had to get the total. That's what I observed so it may not be totally right, but it seems to be although I only confirmed up to 4.

1 is a 50% increase(from 0) so half of that is 25% which means your chances for 2 are 75%.
To get to 75% you had a 25% increase so half of that is 12.5% which means your chances for 3 are 87.5%.
Then 93.75% for 4, 96.875% for 5, 98.4376% for 6 and so on and so forth until it gets ridiculously close to but never reaching 100%.

There's probably something to take into account that it would be impossible to not reach 100% if you get more than half the sac, but I'm not a statistics guy so I have no idea there.
 
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Tim Benzedrine

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Tee-hee! Math is hard!

Alrighty then, just for fun...one of the slings hooked out, leaving five to be determined. What's that do? Statistically speaking.
 

viper69

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Tee-hee! Math is hard!

Alrighty then, just for fun...one of the slings hooked out, leaving five to be determined. What's that do? Statistically speaking.
If you assume the each sac from each species, produces a 50/50 split of the genders (which we don't know obviously). Your odds of getting a female for any of them is 50%. Discovering the gender is called an 'event'. So the odds of getting one gender in one species, do not influence the odds of the next event. However, if you were getting slings from the same sac, assuming a 50/50 split, then the odds of getting a particular do change, they will increase.
 

Poec54

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I'm not seeing the point to this thread. All sacs ARE NOT 'created equal.' There's no reason to assume a 50/50 sex ratio with any tarantula species. Humans aren't even born at a 50/50 ratio; young male Homo sapiens have a certain attrition rate in establishing themselves thru various challenges and risks, and have an extra 3 percentage points over females to cover the losses. By the time they reach maturity, the sex ratios have become equal.

Each species of tarantula has carefully evolved it's sex ratios over thousands of years to fit it's specific habit depending how far the males have to travel, how intense predation is, how much foliage cover is available, how spread out females are from each other, how aggressive the females are towards males, etc. Some situations require extra males to ensure enough make it to mate with all of the receptive adult females. In other cases males don't have to travel far and females may be concentrated, so one male may be able to mate with a number of females.

Look at the variation in the number of eggs per sac, the size of the slings, and rate of growth. Those have also evolved to be part of their survival strategies. Some large South Americans like Lasiodora and Acanthoscurria have huge numbers of tiny slings, whereas Theraphosa has a much smaller number of large slings. Generalizations don't work.

Of the juvenile tarantulas I've had over the decades, there's probably been around 60-65% males overall. In some, females slightly outnumber males, and in others males are scarce. I've had some where almost all have been males (and were too small to sex when I got them).

So, with the understanding that all sacs 'are not created equally', the best advice is to get 5 to 10+ slings at a time of a species if you're looking for females. Don't forget you also have to cover potential losses from bad molts. Even with getting 10 slings of a species you could wind up with 2 females. Do not get one of this, one of that. Usually a big disappointment. Because sex ratios are so variable, get as many slings at a time that you can afford of a species. Sell/trade the surplus once you can sex them. Breeders are always looking for males.
 

viper69

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Tim wanted numerical answers, and for his question the only way to give him an answer is one has to assume a 50/50 split. We all know it's not real world.
 

Tim Benzedrine

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I'm not seeing the point to this thread.

Point? Have you not read any of my ramblings? :D ;)

I was just trying to get a handle on the way it worked, actually. They say that one should buy X amount of s'lings to have a chance of getting Y number of the desired sex. My math skills are almost non-existent, I really suck when it comes to calculations. Of course, I knew that no sacs were created equal, I just thought it might make it simpler.
I'm sure I'll be disappointed, but all of my s'lings were gifts, I only chose one of the bunch. I was only expecting it and possibly a freebie, but the gifter decided to be generous and plus I'm sure figured in the adage of paying as much for shipping as one does for the actual spider is silly. I'm hoping it will be female, but I know that chances are as good that it won't be as that it will.
In short, I was just wondering if the odds charts referred to all of the same species or just the general odds altogether. I suspected it applied to a single species, but was just curious since I had not seen that explicitly stated.
 

viper69

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Point? Have you not read any of my ramblings? :D ;)

I was just trying to get a handle on the way it worked, actually. They say that one should buy X amount of s'lings to have a chance of getting Y number of the desired sex. My math skills are almost non-existent, I really suck when it comes to calculations. Of course, I knew that no sacs were created equal, I just thought it might make it simpler.
I'm sure I'll be disappointed, but all of my s'lings were gifts, I only chose one of the bunch. I was only expecting it and possibly a freebie, but the gifter decided to be generous and plus I'm sure figured in the adage of paying as much for shipping as one does for the actual spider is silly. I'm hoping it will be female, but I know that chances are as good that it won't be as that it will.
In short, I was just wondering if the odds charts referred to all of the same species or just the general odds altogether. I suspected it applied to a single species, but was just curious since I had not seen that explicitly stated.
Tim, egg sac aside (which is the central determining factor haha), one event doesn't influence the other in this probability context.
 

MrDave

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Tim, egg sac aside (which is the central determining factor haha), one event doesn't influence the other in this probability context.
Exactly. If you have 5 slings, and the first 4 are male, then the 5th is just as likely to be male as any other.
 

Ellenantula

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True. If a woman has 6 daughters, her chance of a male next birth is unaffected by the previous 6 -- it's still 50-50 (actually slightly skewed but 50-50 for sake of argument).
Likewise if I flip a coin 100 times and it always lands on heads, my 101th throw is still a 50-50 because previous events do not affect the odds -- I'm not "due" for a tails because they are all independent events..
(Although if that really happened, I'd like an expert to examine that coin!)
 

Poec54

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- Point? Have you not read any of my ramblings?

- I was just trying to get a handle on the way it worked, actually. They say that one should buy X amount of s'lings to have a chance of getting Y number of the desired sex. My math skills are almost non-existent...I just thought it might make it simpler.

- In short, I was just wondering if the odds charts referred to all of the same species or just the general odds altogether.

- No more than absolutely necessary.

- Because males often tend to outnumber females (by an unknown amount), the advice is simply to get 'plenty' of slings of a species at a time, as many as you can afford. There is no magic number, ever. You can get 2 slings and have 1 turn out to be female. Or you can get 10 slings and have 1 female. Even if a species would happen to have a 50/50 ratio, that's overall, and every sac isn't going to be perfectly equal, just as some human families have much more of one sex than the other, sometimes only one sex.

- Because tarantula sex ratios vary widely, and we don't even know what any of them are, then there's no point in any math that follows. There's no solid starting point.
 

Tim Benzedrine

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- No more than absolutely necessary.
-Hmm...that's good, because you really wouldn't enjoy the ones you don't read either. :D
Of course, what's the use of posting a legitimate thread when you are going to be informed that there is no point in it? Might as well post drivel, eh? Just be glad it wasn't "I'm a newbie, should I get an OBT?" :D
 

Tcollector

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- No more than absolutely necessary.

- Because males often tend to outnumber females (by an unknown amount), the advice is simply to get 'plenty' of slings of a species at a time, as many as you can afford. There is no magic number, ever. You can get 2 slings and have 1 turn out to be female. Or you can get 10 slings and have 1 female. Even if a species would happen to have a 50/50 ratio, that's overall, and every sac isn't going to be perfectly equal, just as some human families have much more of one sex than the other, sometimes only one sex.

- Because tarantula sex ratios vary widely, and we don't even know what any of them are, then there's no point in any math that follows. There's no solid starting point.
This is correct.

When getting slings I get a minimum of 3 and a max of 6 if I'm trying to get a female. When I got back in the hobby I started with 3 P. regalis slings. All of them are 6" now with 2 of them female.

Get as many slings per species that you can afford. I personally like to buy 1 female per species with 3 or 4 slings extra for that species.
 

Poec54

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Of course, what's the use of posting a legitimate thread when you are going to be informed that there is no point in it?
This thread revolves around sex ratios, which vary and haven't been studied. Without something tangible to go on, you can't do any math calculations. This is still a new hobby and most things about tarantulas aren't known yet. We don't even know how many kinds of tarantulas there are. We're still figuring out how to breed what we currently have in captivity. Many are challenging, so figuring out sex ratios is a long ways off. It requires raising up a number of sacs for each species, and keeping all the slings. Who has the time/space/money to raise hundreds of thousands of spiders to a sexable size? And preserve all those molts and put them under magnification? How many people can even raise up all the slings in a single LP sac? There is no funding for this; it's just hobbyists and their resources are limited. Dealers can't sit on that many slings for a study; they need cash flow to stay in business. If you're a young man, maybe sex ratios will be figured out in your lifetime. Maybe.

Now you know.
 

Tim Benzedrine

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Therein lies my initial confusion. The chart, which I believe is in TKG, did not specify single species. Now, what little common sense I have told me that it must mean a single species, but then I thought, "Well, maybe there is some crazy law of averages I am missing." I'll admit that it is even more likely my reading comprehension was off.

Eh, that's why I prefer to try to give people a chuckle. My attempts at being serious almost always fail. :eek:
 
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