How to measure your "T"

[Clinton Hogben]

Just a quick one for the new year is their a correct way to measure your little monster
My L Para has just moulted this morning and I placed the shed skin on a one inch grid (piccy attached) the front to back dimensions are 6 inches thats without stretching / flattening out the skin but obviously once she puffs herself up and dries the new skin will probably take her to over seven inches does anyone know of the proper way to measure without upsetting or stressing out the monster cos at the end of the day its only curiosity and not worth stressing the spider out by handling her



Cheers

Clinton

[Stanley A. Schultz]

... is their a correct way to measure your little monster ...

In a nutshell, no. Virtually every scheme that has been proposed has some serious failing. Here are some of them:

1. Tarantulas change shape and proportions
a. As they grow.
b. As they gain weight.
c. As they drink.
d. As they mature.

2. Living tarantulas are remarkably reluctant to let you measure them.

3. Shed skins are stretched way out of proportion so they aren't very good references under the best of circumstances.

4. The measurement you take depends on whether the tarantula is relaxed or tense, outstretched or wadded up, etc.

And lots more confounding issues.

"Sam Marshall (Tarantulas and Other Arachnids, 2001) has suggested using the length of the femur of the front legs as a good measure by which to compare tarantulas' sizes. This is probably a much better measure for scientific purposes than any other because this dimension would not vary appreciably depending on the tarantula's state of obesity or hydration. However, it still carries major problems when comparing animals of different sex or species. Also, from the enthusiast's point of view, one must admit that stating that one's tarantula has a 4.67 centimeter femur length just doesn't have the same impact as stating that it has a thirty centimeter leg span!" (Third edition of The Tarantula Keeper's Guide, in process.)

As a result, just about any measurement that's given is really only a guesstimation and often subject to a lot of "poetic license." It's been said that women always lie about their weight, guys about their height, and tarantula owners about the size of their tarantulas.

Generally, the two measurements most commonly used are

1. Leg span. The distance from the tip of one front leg to the tip of the rear leg on the opposite side when the tarantula is in a relaxed, stretched-out posture.

2. Body length. The length from the front of the tarantula (i.e., the most forward part of its chelicerae) to the rearward most part of its opisthosoma (abdomen) exclusive of the spinnerets.

For most immature tarantulas and mature females, the ratio between these two measurements is about 2:1 within reasonable levels of accuracy; so you can translate from one measurement to the other when making comparisons. Adult male tarantulas vary too much in proportion to be able to make any such ratio claims.

Enjoy your 40" (one meter) tarantula!

[Clinton Hogben]

Hi Stan
Wow thats a pretty comprehensive answer thank you for taking the time to post it
My L Para (female about 18 months old) was about 3 inches fangs to tail so using your equation of 2:1 would make her about 6 inches pre moult
She is stretched out drying/hardening off in the viv at the moment after this moult and looks a lot bigger now than before
but as you say it like the story of that big fish you caught when you were on your own it grows with each telling of the story
At the end of the day I am just happy she is fit and well, I only got her 4 months ago and this is her second moult with me so she must be fairly happy in her environment.
Once she is big enough to pick up her viv and a box of crickets then move house by herself I will know she is truly a monster

All the best

Clint