Reasons behind theraphosid markings and colours

[Rich.Harrington]

Tried doing a search with regards to this topic and couldn't find much.

I was sat doing the usual upkeep and record of the spiders today when I came to wonder why some are coloured in certain ways.

Now for some this can be explained with logic, the archetype b.smithi for instance does have colour markings that are indicative of all poisonous/venomous cratures, with the classic black & yellows.
Some also tend to have markings that help facilitate an exellent camouflauge scheme.

However the vast majority seem to have colours that fit neither of these two basic principles of nature. Of course there is the third reason, being that of mating, however this also does not fit for theraposhids due to their very poor eyesight, where some may not even be able to discern colours, let alone detailed markings.

So has there been any theories put forward to offer explaination behind this question?

[Nicola Dolby]

Hi Rich,
What you say is a very good point. I'm pretty sure that a lot of the colouration and markings is designed to help the spiders blend in with their natural habitat. Take for example Brachypelmas. If you've been to Mexico or seen A. Smith's DVD you'll know that colouration of the soil in some parts is brick red. You could be sitting next to a B. bohemi or a B. baumgarteni and not know it was there until it moved! A lot of African tarantulas are camouflaged similarly and the only exceptions, the blue ones; well all I can think of is that they're saying "Look how bright I am, I must taste foul.
Myself I think you should go for the research on this yourself. Even if it turns out to be a camouflage thing, you'll still have proved it!

[Mark Pajak]

I agree with Nicola that Brachypelma smithi colouration is more a case of camoflague (crypsis) rather that warning colouration (aposematism).

For more obvious warning colouration the underside of Poecilotheria are a good example. And they more or less dissappear when in front of bark (their natural resting place) so the striking grey/white/black on the upper surface do actually seem to be a case of camoflage.

....so I think even some of the strikingly coloured species are actually just hiding amongst undergrowth... think of tigers, or zebras for example - out of context they are umisssable, but in their natural habitat they blend right in.

[Ray Hale]

I am currently working on adaptive colouration in tarantulas and spiders in general and am working towards an article for the BTS Journal and lecture.

Watch this space.

Ray Hale

[Nicola Dolby]

Great news about the research Ray, should be a good read.I can see about the camouflage, even M. balfouri ould hide well in the dark as its legs are a deep blue, almost navy coloured without sunlight. But without wishing to sound stupid (and I often do), where is a P. metallica camouflaged? I'm not aware of how many blue wall murials they have near Gooty, but I can't think of anywhere else it would blend in.!

[matthew spooner]

the main reason for all these beautiful markings and colours in Ts is simple, to look bloody fantastic for us collectors lol