I've not been the most active of writers on this blog of late but, fear not, I'm going to write another series of posts as I blog/blather from the field.
|Lizard Island, Australia. Photo: Michael Bok.|
|A mantis shrimp (stomatopod).|
The word that binds our research together is polarization. If my colleagues and I were the mince, polarization would be the egg that binds us together forming the burger (?!) that is our group. Slightly off the beaten (egg) track.
Serious science time:
What is polarization?
|Unpolarized light coming from a light source is oscillating at all|
possible angles in that plane, however, when it is passed through a
filter (polaroid) it becomes polarized, oscillating only at one angle.
How can an animal detect polarized light?
We, as humans, know that polarized light exists around us, but unfortunately, without polaroid filters, we cannot see it. Unless of course you are one of the lucky few who have deliberately tried to view strong sources of polarized light such as LCD monitor outputs and are now cursed, forever having a strange yellow bow tie shape appear randomly on the desktop. It's called Haidinger's brush if you fancy having a go yourself. To detect polarized light oscillating at one angle, your photoreceptors must be aligned at that same angle, to absorb the maximum amount of light. If your photoreceptor is, say, 90degrees out compared to the polarized light, then it's not going to absorb very efficiently. This sort of arrangement of photoreceptors where one lies at one angle and a second, connected photoreceptor is lined up perpendicular to it, is very common in invertebrates and is the basis for their polarization vision. Simply put, it allows them to compare the outputs of these two receptors and figure out what angle the light is oscillating at.
Why is polarization vision useful?
|Unpolarized light bouncing off the surface of the|
water becoming polarized horizontally.
Photo: Wehner (2001).
I still haven't got to the bit where I explain what we are doing in Australia. I think that is quite enough for one post, time for a cup of tea.