Light sensitivity?

[Bill S]

Pokies and Lampropelma seem sensitive. I move the light I need slowly and that seems to help them not freak.

One of the L.violaceopes slings I have did a threat pose when a flash light was shone in front of him.

That may show a sensitivity to movement rather than an aversion to light. Tarantulas do have eyes, and although they probably don't have much acuity in their vision, they can certainly see movement.

 

[curiousme]

That may show a sensitivity to movement rather than an aversion to light. Tarantulas do have eyes, and although they probably don't have much acuity in their vision, they can certainly see movement.

I wouldn't say that they can 'see' movement. They really 'feel' movement.(air currents, web line movement etc.) From my understanding and reading, they only register light and dark with their eyes, which are otherwise useless.

 

[jebbewocky]

All I know is it irritates my H.mac, my Pokie, my L.parahybana, and none of my other T's give a crap even remotely. This isn't just camera flashes, but flashlights, and even a UVA light I tried using to regulate their day night cycles. I had the time and light leftover from when I had leopard geckos, so I figured I'd try it. It just made the aforementioned ones hide more.

 

[Bill S]

I wouldn't say that they can 'see' movement. They really 'feel' movement.(air currents, web line movement etc.) From my understanding and reading, they only register light and dark with their eyes, which are otherwise useless.

Research done with other spiders shows a wide range of use and accuity in different types of eyes. Some, like the large frontal pairs of jumping spider eyes, can see in color and function almost like telescopes. Their lateral eyes function as motion detectors. Some spiders have eyes that can see polarized light and are used for spatial orientation. I haven't seen comparable research on tarantula eyes, but they must serve some function or evolution would have eliminated them. (Cave spiders have lost their eyes over a period of time much shorter than that of tarantula evolution.) If they served no other function beyond distinguishing between light and dark, a single pair of eyes would suffice. Rainer Foelix has an interesting section on spider eyes in Biology of Spiders. If you know of papers on tarantula eyes or sight, pleas post links.

As for "feeling" movement - you're thinking of trichobothria. Those are the hairs set into sockets in spidersand in other arachnids that detect disturbances in the air around the animal. They do "feel" movement, but that can be different from motion detection. Let me try to explain.

Take a spider of a species that does detect motion with its secondary eyes (such as a Habronatus) and put it in a glass container. If something approaches from the side OUTSIDE of the glass container, the secondary eyes will see the motion, but the trichobothria won't detect movement because the air inside the glass container won't be disturbed by the outside movement. If you shut off all lights and place a cricket INSIDE the container, the spider's eyes won't see any motion because there isn't any light, but the trichobothria will detect the movement through the disturbance of the air.

In food getting and predator avoidance both visual motion detection and trichobothrial movement detection can play important roles.

Again, I haven't seen any specific research on tarantula eyes and would appreciate it if you (or anyone else) could provide links to such.