# Moult size-growth rate ratio?



## Mavet (Jan 19, 2014)

Hi all, I'm curious if there tends to be a greater jump in size from moult to moult the larger the spider is? I know the rate at which larger spiders moult is much slower than that of smaller spiders, but when larger spiders do moult, do you guys notice a greater jump in size than when smaller spiders moult?

Also, are there certain species or genera in which you find this is more or less prevalent? 

Just wanting to sate my idle curiosity, and maybe develop some questions for further study... 

Cheers.


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## Tomoran (Jan 19, 2014)

By "larger the spider", do you mean larger by species or larger as in a sling compared to a young adult? Also, different species gain more size from each molt than others. An LP sling, for example, will put on much more size during a molt than say a G. rosea sling.


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## prairiepanda (Jan 19, 2014)

I find that it's quite the opposite. Slings can double in size with a single molt, but when a 4" T molts I barely notice a difference. I've seen the same pattern with every species.

Tarantula growth rate for any species tends to slow down as they get larger. Their baby stages are quite vulnerable, so growing up fast is important for survival. But once they start getting big, there's not much pressure to grow fast.


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## Misty Day (Jan 19, 2014)

My p.regalis gains about a half inch with a molt. It went from 1 inch to 1.75 inch in 12 weeks. My gbb sling only gains 1/4 of an inch with each molt and went from 1/2 inch to 1 inch in 12 weeks. 

Really just depends on the species and age.


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## Mavet (Jan 19, 2014)

Tomoran said:


> By "larger the spider", do you mean larger by species or larger as in a sling compared to a young adult? Also, different species gain more size from each molt than others. An LP sling, for example, will put on much more size during a molt than say a G. rosea sling.


I meant within a given species, will you see a greater size increase from moult-to-moult when the spiders are smaller (slings) or when they are larger (juvenile/sub-adult)? I realize that once a tarantula matures, (assuming it's female) any moulting that occurs is for maintenance or regenerative purposes only, and that even if there is some growth taking place it will most likely be negligible. 

I have heard that LPs are infamous for their ridiculous size-increases between moults; any other species that even come close to this? And also, do you guys think there might be a correlation between the time spent between moults and the relative size increase?

For example: one of my GBB slings/juvies has moulted 3 times since I got her in September as a 3cm sling, and has grown ~1cm in size each time. She is now about 6cm DLS, which means she increased 1/3 her pre-moult size during moult 1, +1/4 her pre-moult size during moult 2, and +1/5 her pre-moult size during moult 3.

My other GBB I got in mid-October as a 4cm sling. She's moulted twice so far (she's in pre-moult again now) and increased 1/4 her size to 5cm the first time, then increased 2/5 her size to 7cm the second time. I'll be interested to see if her somewhat faster growth rate starts to slow down during her next moult or if she maintains it for a while longer.

Anyone else have any similarly interesting experiences? Which species have you seen the largest size increases with? The smallest? Do you guys find that tarantula species which grow to be larger as adults also grow the most between moults, or is it the opposite? I'm all ears!!


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## LordWaffle (Jan 19, 2014)

All the Ts I have and all the Ts I've helped raise are all very consistent in that te larger they get, the slower their growth from molts. The growth rate slows down at different times for different species, and obviously the slower growing species tend to not have as many huge jumps in size after molts.

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## Mavet (Jan 19, 2014)

What about tarantulas that have large or very large maximum adult sizes? Do these species exhibit greater growth jumps between moults when the tarantulas are younger than species who's maximum adult size is comparatively smaller?


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## LordWaffle (Jan 19, 2014)

Depends on the species and general growth rate. Take for example G pulchripes versus L parahybana. LPs grow up to 10 inches and G pulchripes can reach around 8 inches. LPs grow very fast up until they get to about 6 inches. My LP meatball has molted three times in my care, each molt being such a large jump that she has more than doubled her size (from about an inch and a half to 4 inches). G pulchripes on the other hand tends to grow much slower overall. Spiderling molts have definitely been larger jumps in size than when they're older, but nowhere near the size differences you see with LPs. I think the big difference in growth rates has to do with lifespan in general, how the spider is kept, and the conditions that the species has in it's natural habitat.

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## Mavet (Jan 19, 2014)

Thanks LordWaffle, that's a really helpful comparison. And that's a pretty crazy jump for one moult! Is there any other species (or genus) of tarantula that has been known to exhibit growth rates/jumps even close to that of an LP? Or are LPs just miles ahead of the rest of the pack?


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## LordWaffle (Jan 19, 2014)

Sorry, it was across three molts. First molt happened within a day of getting her, and was pretty negligible. 1.5-1.75 or so. The next one she got to 3 an the third she got to 4.

---------- Post added 01-19-2014 at 07:57 PM ----------

To answer your question, there are other species that have comparable growth rates that I've seen. A geniculata is a fast grower, so are pokies. I have a T stirmi, but no molting yet and none of my friends have owned any genus Theraphosa spiders, but from what I understand they grow like weeds too.

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## Mavet (Jan 19, 2014)

LordWaffle said:


> Sorry, it was across three molts. First molt happened within a day of getting her, and was pretty negligible. 1.5-1.75 or so. The next one she got to 3 an the third she got to 4.
> 
> ---------- Post added 01-19-2014 at 07:57 PM ----------
> 
> To answer your question, there are other species that have comparable growth rates that I've seen. A geniculata is a fast grower, so are pokies. I have a T stirmi, but no molting yet and none of my friends have owned any genus Theraphosa spiders, but from what I understand they grow like weeds too.


Ah, yes, that sounds a lot more realistic than from 1-4" in a single moult! Thanks for the info. I will definitely keep those species in mind if my research leads in that direction!


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## viper69 (Jan 20, 2014)

Mavet said:


> I realize that once a tarantula matures, (assuming it's female) any moulting that occurs is for maintenance or regenerative purposes only, and that even if there is some growth taking place it will most likely be negligible.
> 
> Anyone else have any similarly interesting experiences? Which species have you seen the largest size increases with? The smallest? Do you guys find that tarantula species which grow to be larger as adults also grow the most between moults, or is it the opposite? I'm all ears!!



I'm not sure if you understand or perhaps you are misswording your concept of molt, could be more clear?

Molting is a sign of growth in the animal, case closed, regardless of its age or the amount of growth which takes place. My adult females still molt, they get larger, there is no "maintenance", whatever does that mean??  Nor were there any missing body parts. Nor do I understand what you meant why writing "negligible". Even a millimeter increase in DLS is an increase in size, be it as a spiderling or as an adult, hence they molt.  Also, while we measure size increases in DLS typically, that is a LINEAR measurement which completely doesn't take into account VOLUMETRIC (the other 2 dimensions) increases in size. It's growing in 3 dimensions.



As for jumps in sizes, there are species that do take great leaps in size. However, I believe from the posts I have read over time, that these leaps in size are not continuous by any means. It depends on the species, and in some cases the gender of that species too, coupled with the life cycle of that T. For example, Poec54 told me that one species (I believe it is the Singapore Blue), the males (can't recall if females do this), go from 4" to 6" in a single molt! That's a huge jump in size. However, before that they don't have such a large increase, mine didn't at least.

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## LordWaffle (Jan 20, 2014)

Viper brings up a very good point with volumetric growth. While every molt brings volumetric growth for obvious reasons, when the T is an adult (especially females) the molts begin to add bulk. DLS is an important indicator for size, but body size is what makes the infamously heavy species like T blondi as heavy as they are.

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## Mavet (Jan 20, 2014)

viper69 said:


> I'm not sure if you understand or perhaps you are misswording your concept of molt, could be more clear?
> 
> Molting is a sign of growth in the animal, case closed, regardless of its age or the amount of growth which takes place. My adult females still molt, they get larger, there is no "maintenance", whatever does that mean??  Nor were there any missing body parts. Nor do I understand what you meant why writing "negligible". Even a millimeter increase in DLS is an increase in size, be it as a spiderling or as an adult, hence they molt.  Also, while we measure size increases in DLS typically, that is a LINEAR measurement which completely doesn't take into account VOLUMETRIC (the other 2 dimensions) increases in size. It's growing in 3 dimensions.
> 
> ...


Ah, I'm not sure I was fully aware of this, thanks for pointing it out! I was under the impression that adult females didn't do much growing after reaching maturity, and that their infrequent moults were a way to 'refresh' themselves, regenerate urticating setae and repair any damage that may have occurred. That does make quite a bit of sense, though, regarding volumetric growth.


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## viper69 (Jan 20, 2014)

Mavet said:


> Ah, I'm not sure I was fully aware of this, thanks for pointing it out! I was under the impression that adult females didn't do much growing after reaching maturity, and that their infrequent moults were a way to 'refresh' themselves, regenerate urticating setae and repair any damage that may have occurred. That does make quite a bit of sense, though, regarding volumetric growth.



Adult females do have a slower rate of growth, but they still continue to grow. Ts don't molt because they have lost setae. You have to remember ALL the setae get replaced in a molt, molting is due to growth of physical body size. This "refresh/maintenance" is not accurate.


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## Mavet (Jan 20, 2014)

viper69 said:


> Adult females do have a slower rate of growth, but they still continue to grow. Ts don't molt because they have lost setae. You have to remember ALL the setae get replaced in a molt, molting is due to growth of physical body size. This "refresh/maintenance" is not accurate.


Gotcha. Thanks for the correction. So basically tarantulas don't stop growing until they die. Awesome!


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## Keith B (Jan 20, 2014)

Skipping all of the complex stuff, I'm just going to generalize, as in what I've seen with most Ts, not all.  Generally you, will see a slightly different growth rate from males to females.  Depending on the species, the male usually grows faster than the female, but mature sooner and ultimately smaller (in mass, and sometimes legspan).  Most T's grow about the same incrementally until they've reached close to full size.  It will seem like they grow more as adults because of the size difference, but in fact, grow about the same.  For example a 3" LP molting to a 6" LP is the same as growing from a .5" to a 1", but the growth at a larger size appears more impressive.  Keep in mind though, that it takes more time to achieve this growth as they get older.  There are plenty of species that rival the growth rate of LPs, the difference is though, that they don't grow as large, and therefore get less "hype" for it.  Like was mentioned about the Lampropelma growing from 4 to 6".  Most arboreals grow immensely between molts.  But the difference is that most arboreals just don't get as impressively large as an LP.


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## jgod790 (Jan 22, 2014)

Sorry, kinda off topic. Does T. Stirmi compare to LP as far as growth rate goes? I have a 6" stirmi, just wondering how fast untill it is 8" or more.


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