It’s been a rough week, and next week will be even rougher. I seem to have accumulated a collection of scheduled committee meetings. On top of that, I’ve got my first heavy dollop of grading to get done, and next Friday is a big math day which is always frustrating for some of the students.
So today I’m playing hooky and skipping town! Mary and I are heading north with a cooler to stock up on groceries, and to make a field trip to the ecostation looking for spiders. I shall emerge rested and refreshed later this afternoon, I hope.
If you haven’t read this Onion article yet, you should: https://www.theonion.com/and-after-the-100-foot-tall-spiders-destroy-the-cities-1844845891
So now I’m curious, what parts of the EM spectrum do (some? all?) spiders see?
Spectral sensitivity of a colour changing spider
JérémyDefrizea
Claudio R.LazzariaEric J.WarrantbJérômeCasasa
https://doi.org/10.1016/j.jinsphys.2011.01.016
Abstract
Vision plays a paramount role in some spider families such as the Salticidae, Lycosidae and Thomisidae, as it is involved in prey hunting, orientation or choice of substrate. In the thomisid Misumena vatia, for which the substrate colour affects the body colour, vision seems to mediate morphological colour changes. However, nothing is known about which component of visual signals from the substrate might be perceived, nor whether M. vatia possesses the physiological basis for colour vision. The aim of this study is thus to investigate the vision of this spider species by measuring the spectral sensitivities of the different pairs of eyes using electrophysiological methods. Extra- and intracellular electrophysiological recordings combined with selective adaptation revealed the presence of two classes of photoreceptor cells, one sensitive in the UV region of the spectrum (around 340 nm) and one sensitive in the green (around 520 nm) regions in the four pairs of eyes. We conclude that M. vatia possesses the physiological potential to perceive both chromatic and achromatic components of the environment.
… of course, your spiders may vary.
Humans see down to about 380nm. So spiders can see way out in the UV. PZ’s choice of IR camera means that they likely can’t see the light he uses.
Since spiders fluoresce, they have proteins that interact strongly with UV which means they may be colorful in the UV.
https://royalsocietypublishing.org/doi/10.1098/rsbl.2007.0016
Spiders fluoresce variably across many taxa
Kindra Andrews , Scott M Reed and Susan E Masta
Published:03 April 2007https://doi.org/10.1098/rsbl.2007.0016
Abstract
The evolution of fluorescence is largely unexplored, despite the newfound occurrence of this phenomenon in a variety of organisms. We document that spiders fluoresce under ultraviolet illumination, and find that the expression of this trait varies greatly among taxa in this species-rich group. All spiders we examined possess fluorophores in their haemolymph, but bright fluorescence appears to result when a spider sequesters fluorophores in its setae or cuticle. By sampling widely across spider taxa, we determine that fluorescent expression is labile and has evolved multiple times….
Not on color vision but structure: https://www.wired.com/2014/04/spider-vision-made-clear/
.. but most spiders don’t have the great vision that jumping spiders do.
I know my own vision is poor, but now I’m wondering why the helpful & informative comments on IR and spider-vision are being made in this thread, rather than in the almost-immediately-previous thread (about poopyhead’s IR camera trial experiment), Night moves…
</snark>@ 3-5 bcwebb
Thank you!!
@ 6 blf
My fault, I thought that I was posting to the previous thread when I submitted @2.
No one, at the end of their life, has ever said “Oh, I wish I had attended more committee meetings”.
I remember a time, many years ago, when I was invited to a summer retreat on the shore of West Lake Okoboji in Iowa. We got to the house and it was filled with spiders.
We vacuumed them up.
I feel now as if I was a mass murderer.
stroppy@7, Yeah, I kind-of guessed it was something as trivial as that. Just to make very very clear: Those comments are very interesting, I am not criticising you or anyone else, I am not “policing” the comments in any sense except for amused, and I myself do the same silly (if I may use that word) thing. Thanks!