Colour forms - for what??

[Thomas Grabiec]

Hi all.

As everyone knows, tarantulas have a lot of different colour forms. Could anybody tell me - for what do they need them?? Why can't they be f.e. just in normal colour form?

I've already asked a few guys and they do not know. Hope I will find it here.

All the best
Tom

[Colin D Wilson]

I think it's just regional variation that could depend on habitat (relating to camoflage etc), it interested me a few years back when it was mentioned that Aphonopelma seemanni was found in differing conditions and had a light and dark coulor form, some speculated that the colour change could be due to humidity and it seemed fairly logical.

I messed around with a couple of Grammostola rosea (which we knew them as at the time) and placed a couple on dry light substrate (coir / vermiculite / peat) and a couple on darker substrate (compost / peat / soil) which held water more readily. at the end of this little experiment (well over a year) when they had grown to juvenile size there was a noticable difference to the overall colour and the couple kept on the darker substrate were more a "dirty brown" colour to the light tan colour of the second lot, the carapace was a deeper pink too.

I tried the same with Brachypelma vagans, some on just vermiculite, some on peat, others on light coir but they showed no colour change ... they did however show a remarkable difference in growth, one outcome which i did not expect was those kept on vermiculite (just regular food and no water) grew at a rate higher than those on peat that was moistened weekly when being fed at the same time.