Best Flashlight Color for Tarantula Viewing

[bryverine]

I found a study on tarantula eye sensitivity awhile back and I waited until I could find someone to give me permission to use the data in the plot I made below.

The data shows the maximum normalized sensitivity.
The background shows the approximate color of each wavelength (I did it in excel as a background gradient, so if the colors are a little off, that's why)


This shows to me that the best flashlight color for the human eye while minimizing tarantula disturbance is indeed a red one! If I wanted to find the best flashlight (or worst I guess) for my eyes and not the tarantula, I'd consider the following plot.


Looks like anything around orange or lower frequency will do the trick!

Data for the tarantula vision came from:
Dahl, R. D.and A. M.Granda.1989.Spectral sensitivities of photoreceptor in the ocelli of the tarantula, Aphonopelma chalcodes (Araneae, Theraphosidae) . J. Arachnol ., 1 :195-205

 

[EulersK]

Wow, awesome. I'm certainly saving these pictures, thank you very much for sharing! One question, though. It appears as if the key isn't set up quite right. In the first graph, which color represents the tarantula's sight? I'm assuming red, given how the curve is.

 

[bryverine]

Sorry, I think the keys are correct, but they are a bit on the light/small side (it looked ok when they were bigger ). The blue-ish one is indeed 'people vision' the other is 'tarantula vision'.

 

[Radium]

I already had a red flashlight for astronomy when I started keeping, so this confirms that I was correct in being cheap. Awesome graphs!

 

[assidreemz]

yes, i have found that my t's arent disturbed by my dim red headlight used indirectly

 

[Chris11]

I use both red and blue light, depending on the enclosure material, red goes through glass and kks better, but blue shines through thin plastic better imo... none of my spiders notice if i shine them directly.

 

[AphonopelmaTX]

I found a study on tarantula eye sensitivity awhile back and I waited until I could find someone to give me permission to use the data in the plot I made below.

Could you provide an explanation on how to interpret these graphs? What is normalized sensitivity?

 

[JLPicard]

For budgetary motives, I have to ask, would this include bike lights?

 

[soundsmith]

For budgetary motives, I have to ask, would this include bike lights?

You can get a red LED flashlight on eBay for like $9 shipped.

 

[JLPicard]

9$ can make the difference between a full belly and an empty one at the end of the month. I'm on a student budget, haha.

 

[soundsmith]

9$ can make the difference between a full belly and an empty one at the end of the month. I'm on a student budget, haha.

I know those times.

 

[bryverine]

Could you provide an explanation on how to interpret these graphs? What is normalized sensitivity?

Sure thing! These plots were made to illustrate the capability of the different receptors (cones or eyes) to a span of wavelengths.

For normalization, basically I just divided all the data by the maximum value leaving a new maximum of 1. Though it gets rid of any units, it makes it much easier to compare data and stays away from those nasty log plots…

I did this for each of the cones in the human eye and the tarantula data.

For the human data, I took all three cone sensitivities, normalized them and then overlaid the signals (Note: I did not add them). Our total vision is a little different because cones actually overlay a bit so it makes a sort of lumpy looking shape. Search google images for “photopic vision”. In other words, these plots do not show what our eye actually perceives for each wavelength as far as intensity but give a pretty good idea about the capability of each cone.

From this article, I gathered that tarantulas can distinguish light differently depending on the eye the light is seen through. The test in the article was specifically done on the following: anterior median eye, anterior lateral eye, posterior median eye, and the posterior lateral eye. I think that this means front to back on one side. I normalized this data and found the max capability at each wavelength to get the “total” tarantula vision plot.

I'm not sure if this is what you were asking or not, but I think that explains it?

Also, you can read the lines below if you are really interested in equations n' things.

Sciency stuff:
Sensitivity usually measured in Lumens = (Radiant power in watts)(Constant)(luminous efficiency for specific light)

Perceived Intensity or sensitivity to different colors for humans of a 5mW monochromatic light source
450 (blue)
.005W*773.500=3.87 [lumens]
532 (green)
.005W*1378.700=6.89[lumens]
632 (red)
.005W*5.670=0.028[lumens]​

Normalization - X'= (X-X[SUB]min[/SUB])/(X[SUB]max[/SUB]-X[SUB]min[/SUB]) but because X[SUB]min[/SUB] << X[SUB]max[/SUB]- (like 6 orders of magnitude or 1,000,000 times smaller) X'= X/X[SUB]max[/SUB]- .

 

[viper69]

Sure thing! These plots were made to illustrate the capability of the different receptors (cones or eyes) to a span of wavelengths.

I have to weigh in here as I don't think you have properly communicated what you know.

Eyes aren't receptors at all when mentioned in the biology world of science, the way you wrote it gives the reader the impression that the author (you) thinks eyes are receptors; they aren't. Photoreceptors are a type of neuron that are light-senstive, eyes are not photoreceptors, they are organs. Cones and Rods are different neuronal cell types which are types of photoreptors. In point of fact, there are different types of cones for different colors as you alluded to, but I digress.

 

[bryverine]

Thanks for helping me not sound silly! What you say is true.

With my limited understanding of the complexities of each individual tarantula eye, I made a blanket statement and compared the sensitivity of the all of the tarantula's eyes (each full of receptors) to the sensitivity of our color receptors.

Each eye had slight variations in it's sensitivity which I can assume is due to different receptor concentrations. I went ahead and overlaid them to compare to the human receptor sensitivity overlay.

I hope that's correct and if it is, I hope it explains what I should have said.

Thank you for your input Viper, I appreciate you clarifying that.

 

[Fullyauto12]

I had a question reguarding this post. It may seem kinda of beginner knowledge, but I am a beginner and would like to educate myself. When you mention light sensitivity. What exactly does that mean, as far as if you used a white led light vs a dim redled one like suggested.

 

[viper69]

I had a question reguarding this post. It may seem kinda of beginner knowledge, but I am a beginner and would like to educate myself. When you mention light sensitivity. What exactly does that mean, as far as if you used a white led light vs a dim redled one like suggested.

In a general way re Ts and light, we just mean how sensitive they are to light. Some species/individuals of the same species even, are more sensitive to light than others, based on observations but nothing scientific in my case.

Regarding spectral sensitivity, some neurons ( a type of cell ) in the retina (your retina is the only exposed portion of your Central Nervous System in the human body) are more sensitive to different wavelengths of light than others. In other words, some retinal neurons are more likely to detect certain wavelengths of light than other neurons in the retina.

Unrelated, but some insects can see in the ultraviolet spectrum, whereas humans cannot because our neurons are not sensitive to that portion of the spectrum.

 

[bryverine]

White is a combination of all the different colors and for human eyes, is the combination of red, blue, and green. LEDs actually utilize the combination quite well; look at your monitor/phone really close or with a water bead on it. DON'T BREAK YOUR PHONE/MONITOR!!!

As far as LEDs go, depending on the semiconductor material used in a LED (and several other factors) you get different types of 'white' light. Ever notice how some lights look more blue or red? It's because there actually is more blue or red in the white light.

Back to the flashlight question, I think that even if you get a BRIGHT red light, it would stimulate a tarantulas less than a dim white light.

---------- Post added 12-16-2015 at 01:38 PM ----------

Unrelated, but some insects can see in the ultraviolet spectrum, whereas humans cannot because our neurons are not sensitive to that portion of the spectrum.

Not unrelated at all! I actually have a 'bad flashlight' choice shown in the near UV spectrum.