Abstract
Members of the billfish family are highly visual predatory teleosts inhabiting the open ocean. Little is known about their visual abilities in detail, but past studies have indicated that these fishes were likely to be monochromats. This study, however, presents evidence of two anatomically distinct cone types in billfish. The cells are arranged in a regular mosaic pattern of single and twin cones as in many fishes, and this arrangement suggests that the different cone types also show different spectral sensitivity, which is the basis for colour vision. First measurements using microspectrophotometry (MSP) revealed a peak absorption of the rod pigment at 484 nm, indicating that MSP, despite technical difficulties, will be a decisive tool in proving colour vision in these offshore fishes. When hunting, billfish such as the sailfish flash bright blue bars on their sides. This colour reflects largely in ultraviolet (UV) light at 350 nm as revealed by spectrophotometric measurements. Billfish lenses block light of wavelengths below 400 nm, presumably rendering the animal blind to the UV component of its own body colour. Interestingly, at least two prey species of billfish have lenses transmitting light in the UV waveband and are therefore likely to perceive a large fraction of the UV peak found in the blue bar of the sailfish. The possible biological significance of this finding is discussed.
Full Text
The Full Text of this article is available as a PDF (243.6 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Hart N, Partridge J, Cuthill I., I Visual pigments, oil droplets and cone photoreceptor distribution in the european starling (Sturnus vulgaris) . J Exp Biol. 1998 May;201(Pt 9):1433–1446. doi: 10.1242/jeb.201.9.1433. [DOI] [PubMed] [Google Scholar]
- Levine J. S., MacNichol E. F., Jr Visual pigments in teleost fishes: effects of habitat, microhabitat, and behavior on visual system evolution. Sens Processes. 1979 Jun;3(2):95–131. [PubMed] [Google Scholar]
- Loew E. R., Lythgoe J. N. The ecology of cone pigments in teleost fishes. Vision Res. 1978;18(6):715–722. doi: 10.1016/0042-6989(78)90150-5. [DOI] [PubMed] [Google Scholar]
- Lythgoe J. N. Visual pigments and environmental light. Vision Res. 1984;24(11):1539–1550. doi: 10.1016/s0042-6989(84)80003-6. [DOI] [PubMed] [Google Scholar]
- Munz F. W., McFarland W. N. Part I: Presumptive cone pigments extracted from tropical marine fishes. Vision Res. 1975 Oct;15:1045–1062. doi: 10.1016/0042-6989(75)90001-2. [DOI] [PubMed] [Google Scholar]