Postprocessing as a fish. How to?

Fish do not see reds the way we do but much else is the same; stealth and camouflage is everything.

On the off chance that there is interest in learning how to render images "naturally", i thought i'd start a thread. Perhaps this means simply collecting from the literature, the spectral sensitivities of various marine animals?

   Visual pigments and the acquisition of visual information.

   Lythgoe JN, Partridge JC.

   Department of Zoology, University of Bristol.

   Journal Experimental Biology

   1989 September   146:1-20   Link    On-line Medical Dictionary

 

All the information available to the brain for the interpretation of the visual scene comes

from the number of photons absorbed by a very limited number of photoreceptor types

which are characterized by their spectral sensitivity.

 

In vertebrates there are considerable differences in the spectral absorption of the rods

and cones making up the retinal mosaic of different animals and, in some cases, including

fish and primates,  there are considerable differences between the cone sets of individuals

within a species.

 

Broadly speaking, the spectral sensitivity of the photoreceptors is related to the spectral

distribution of the ambient light and this is particularly true of the colour-biased light

under water.

 

When an animal migrates from one visual environment to another, its cone complement

may change to that suited to the new conditions.

 

However, significant differences between the cone sets of animals living within the same

environment and colour vision polymorphism within a species suggest that visual tasks

critical to survival or breeding success require particular visual pigment sets.

 

A start has been made in trying to understand what tasks are best served by different

pigment sets.

 

   Publication Type:   Review

   Hidden in plain sight: the ecology and physiology of organismal transparency.

   Johnsen S.

   Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

   Biological Bulletin  

   2001 Dec;201(3):301-18   Link     On-line Medical Dictionary

 

Despite the prevalence and importance of transparency in organisms, particularly pelagic species, it is a poorly understood characteristic.

 

This article reviews the current state of knowledge on the distribution, ecology, and physical basis of biological transparency.

 

Particular attention is paid to the distribution of transparent species relative to their optical environment, the relationship between transparency and visual predation, the physics of transparency, and what is known about the anatomical and ultrastructural modifications required to achieve this condition.

 

Transparency is shown to be primarily a pelagic trait, uncommon in other aquatic habitats and extremely rare on land.

 

Experimental and theoretical studies in terrestrial, freshwater, and marine ecosystems have shown that transparency is a successful form of camouflage, and that several visual adaptations seem to counter it.

 

The physical basis of transparency is still poorly understood, but anatomical observations and mathematical models show that there are various routes to transparency.

 

Future avenues for research include examination of the ultrastructure and optical properties of transparent tissue, exploring the link between transparent species and special visual modifications in the species they interact with, and analysis of the evolution of transparency using comparative methods.

 

   Publication Type: Review

   Visual pigments in the early life stages of Pacific northwest marine fishes.

   Britt LL, Loew ER, McFarland WN.

   School of Aquatic and Fishery Sciences, University Washington, Seattle, WA 98195, USA.

   J Exp Biol

   2001 Jul;204(Pt 14):2581-7       Link     On-line Medical Dictionary

 

Microspectrophotometry was used to measure the visual pigments in the rods and cones of 22 species of marine fish larvae netted from the surface waters off Friday Harbor Laboratories, Washington, USA.

 

13 species had rods, 12 of which contained visual pigments with a wavelength of maximum absorbance near 500 nm, while one, the sand lance (Ammodytes hexapterus), had its absorbance maximum at 482 nm.

 

The 22 species of fish larvae possessed varied combinations of single, double and twin cones, ranging in peak absorbance from 353 nm to 584 nm.

 

Of these, green-sensitive single cones were present in 20 of the 22 species, and were the dominant cone type.

 

Double and twin cones were present in 13 of the species.

 

Most common were identical green-sensitive (twin) cones (in 11 species).

 

Green/yellow-sensitive double cones occurred in four species.

 

In a single instance (Hemilepidotus hemilepidotus) twin blue-sensitive, twin green-sensitive and double blue/yellow-sensitive cones were recorded.

 

Of particular interest was the finding that 18 of the species had ultraviolet- and/or violet-absorbing single cones.

 

It has been suggested that short-wavelength photosensitivity may be beneficial for planktivory by extending the spectral range over which vision can occur.

 

The high percentage (82%) of ultraviolet and violet visual pigments in Pacific northwest fish larvae supports the prediction that short-wavelength sensitivity may be common in marine fish larvae.

 

PMID: 11511674