Seeing things

Chapter 7 Gonodactylus, the genital-fingered stomatopod

page 100:  mantis shrimp. The Oatmeal explains why these are his new favorite animal.

page 104: trilobite [eyes]...lenses...of calcite crystals. This is a fossil Erbenochile:

page 108: Loosejaw dragonfish shown here:

page 108:  humans. Diversity in these remarkable photographs.

page 113: only a tiny part of the [electromagnetic spectrum]. Represented in this image:

page 113: enhance vision. For example, researchers have found the visible in the invisible: “Once we amplify these small motions there is a whole new world you can look at.”

This is the eighth in a new series of notes and comments on chapters in The Book of Barely Imagined Beings. It appears around the time of the US publication, and adds to an earlier series that appeared around UK publication. 

Full of eyes

Fourteenth in a series of notes and comments on The Book of Barely Imagined Beings
  
Chapter 7: Gonodactylus, the genital-fingered stomatopod

page 101: stompatopods have eight to twelve colour receptors. A podcast by RadioLab used a choir “singing a rainbow” to paint an audio picture of the range of colours that they see.

page 108: the Barreleye fish Macropinna microstoma. Seen but almost beyond belief:

page 113: brilliant light...on [the] bark and leaves in flakes and dapples of gold. I have left a lot out here. Such moments are experienced by many people. For Annie Dillard (whom I first read eight or ten years after the episode I describe in the book), a similar experience occasions this:

I stood on the grass with lights in it, grass that was wholly fire, utterly focused and utterly dreamed. It was less like seeing than like being for the first time seen, knocked breathless by a powerful glance...I had been my whole life a bell, and never knew it until at that moment I was lifted and struck. 

 page 113 technological stomatopod. John Grotzinger, the project scientist for Mars Science Laboratory mission, i.e. Curiosity, writes “several of our 17 cameras watched [the stone rounded by stream abrasion] disappear over the horizon.” Grozinger sounds like a whole human being:

in my mind’s eye I can picture the different scenarios that could bring that little stone into existence. And to a planetary geologist, each and every one of them has its own inner and outer beauty.

Curiosity: self-portrait

Tough customer

The clubs of the Peacock mantis shrimp Odontodactylus scyllarus withstand repeated very large shocks thanks to the jagged structure of chitinous fibers, which run at cross-angles. [1]  A similar solution was developed for Roman shields (report, paper).

Gonodactylus Smithii, a Mantis shrimp featured in The Book of Barely Imagined Beings,  also uses super-fast clubs to kill its prey.  But I still think its eyes are its most marvelous feature.

Note [1] Or as the original research paper puts it

Consisting of multiphase composite of oriented crystalline hydroxyapatite and amorphous calcium phosphate and carbonate, in conjunction with a highly expanded helicoidal oraganization of the fibrillar chitinous matrix, these structures display several effective lines of defense against catastrophic loading during repetitive high-energy loading events.

Seeing the light

Last year, scientists discovered that [Mantis shrimps] can...see circularly polarised light, which travels in the shape of a helix. To date, they are still the only animal that can see these spiralling beams of light.

The secret lies at a microscopic level. Each eye is packed with light-sensitive cells called rhabdoms that are arranged in groups of eight. Seven sit in a cylinder and each has a tiny slit that polarised light can pass through if it's vibrating in the right plane. The eighth cell sits on top and its slit is angled at 45 degrees to the seven below it. It's this cell that converts circularly polarised light into its linear version.

In technical terms, the eighth cell is a "quarter-wave plate", because it rotates the plane in which light vibrates. Similar devices are also found in camera filters, CD players and DVD players but these man-made versions are far inferior to the mantis shrimp's biological tech.

-- Ed Yong reports on a paper by N.W. Roberts et al.

By contrast some of the simplest known eyes consist of only two cells.

Seeing

Consider the Mantis shrimp, or Stomatopod, which has the most complex eyes in the animal kingdom, with hyperspectral colour vision allowing up to 12 colour (or perhaps 16) channels extending into ultraviolet, advanced depth perception, and an extensive ability to see polarized light. Intriguingly, these animals have little in the way of brains as we think of them.


Consider, too, a kind of seeing known only by Man: the Earth from space. James Lovelock, the man who imagined Gaia, writes:

The icon is undergoing a subtle change as the white ice fades away, the green of forests and grasslands fades into the dun of desert, and oceans loose their blue-green hue and turn a purer, swimming-pool shade of blue as they too become desert. [1]

Footnote

[1] The Vanishing Face of Gaia (2009). But surely the book is mis-titled; the face of Gaia is changing, not vanishing.