This first article must be the one that spawned this factoid...
HOWEVER!! I think the article I've quoted after it shows that only recently have researchers started to work on visual acuity, and that much of the work has been restricted to
UV wavelengths. Of the 211 reef fish tested, 105 could see in the
UV wavelength. You've got to guess that at least a few of these can also see in the infrared wavelengths.
So, the long and short of it is that the factoid may be right in saying that goldfish can see in the infrared and
UV wavelengths of light, but was certainly wrong to assume they are the *only* animals that can. They may be the only animals tested so far that can, but that says nothing, considering there are well over 20,000 species of fish in the world and hundreds of thousands of other types of animals!!
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First Article
Wavelength dependence of visual acuity in goldfish
C. Neumeyer1
(1) Institut für Zoologie III (Neurobiologie), Johannes Gutenberg-Universität, 55099 Mainz, Germany
Received: 2 June 2003 Revised: 22 August 2003 Accepted: 22 August 2003 Published online: 23 September 2003
Abstract Visual acuity was measured in a two-choice training experiment with food reward. Four goldfish were trained to select a homogeneously illuminated testfield when a high-contrast grating (transparancy) was shown for comparison at the second testfield. Measurements were performed for white and monochromatic testfield illuminations in the light adapted state. Fourteen wavelengths between 404 nm and 683 nm were tested. For each wavelength (and white light) the testfield intensity was determined for which spatial resolution was highest. Between 446 nm and 683 nm maximal values of 2.0 cycles/deg (corresponding to a visual acuity of 15' of arc) were found. At 404 nm and in the ultraviolet resolution was lower (0.6 and ~0.25–0.35 cycles/deg, respectively). Cone and small ganglion cell densities may equally account for visual acuity. The action spectrum of maximal visual acuity is very similar to the spectral sensitivity function representing recognition of "colour". Measurements under reduced room illumination and after treatment with Ethambutol further indicate that the detection of high contrast gratings is processed by the same "channel" as colour vision. A similar separate and parallel processing of "colour" and "form" on the one hand, and "brightness" and "motion" on the other hand was found in humans.
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The Second Article
From: Siebeck and Marshall (2001): "Ocular media transmission of coral reef fish — can coral reef fish see ultraviolet light?"
"
UV sensitivity has also been shown for a variety of fish species. It was demonstrated with behavioural experiments in the goldfish (Neumeyer and Hawryshyn), the rainbow trout ( Hawryshyn and Browman), and the roach ( Douglas, 1986). Measurements of the cone photopigments revealed the existence of
UV sensitive photoreceptors in the dace, the carp and a series of other freshwater fishes ( Avery; Harosi and Hawryshyn)."
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