First published online December 3, 2004
Journal of Experimental Biology 207, 4587-4594 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01314
Multiple cone visual pigments and the potential for trichromatic colour vision in two species of elasmobranch
Nathan S. Hart1,*,
Thomas J. Lisney2,
N. Justin Marshall1 and
Shaun P. Collin2
1 Vision, Touch and Hearing Research Centre (Queensland Brain Institute),
University of Queensland, Brisbane, Queensland 4072, Australia
2 Department of Anatomy and Developmental Biology School of Biomedical
Sciences, University of Queensland, Brisbane, Queensland 4072,
Australia

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Fig. 1. Dorsal (A) and lateral (B) views of the giant shovelnose ray,
Rhinobatos typus, showing the raised eyes and crescent-shaped pupil
in the light-adapted state. (C) Light micrograph of the retina of R.
typus showing the duplex nature of the photoreceptor layer (smaller
receptors are cones). gc, ganglion cell layer; h, horizontal cell layer; ipl,
inner plexiform layer; p, photoreceptor layer. Scale bars: (A) 50 mm; (B) 80
mm; and (C) 100 µm.
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Fig. 2. Ultrastructure of rods and cones in Rhinobatos typus. (A) Typical
rod (r) and cone (c) morphology. (B,C) Different types of cone photoreceptors
can be distinguished based on minor differences in receptor size,
mitochondrial alignment and the location of the nucleus in the outer nuclear
layer. (D) High-power micrograph of the outer segment (os) of a cone
photoreceptor showing the lack of a plasma membrane surrounding the discs. c,
cone; cn, cone nucleus; m, mitochondria; my, myoid; r, rod. Scale bars:
(AC) 5 µm; and (D) 0.5 µm.
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Fig. 3. Normalized absorbance spectra of rod and cone visual pigments in (A) the
giant shovelnose ray Rhinobatos typus, and (B) the eastern shovelnose
ray Aptychotrema rostrata. Prebleach spectra (circles) are
best-fitted with a rhodospin visual pigment template of the appropriate
max; postbleach spectra (squares) are fitted with an
unweighted running average. SWS, MWS and LWS refer to short-, medium- and
long-wavelength-sensitive visual pigments, respectively.
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Fig. 4. Spectral radiance along different lines of sight at different depths in
Australian reef and coastal waters. (A) Reef water 1 m depth; (B) coastal
water 1 m depth; (C) reef water 5 m depth; (D) coastal water 35 m
depth. Solid line, down-welling radiance; broken line, horizontal radiance;
dotted line, up-welling radiance.
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© The Company of Biologists Ltd 2004