Hostname: page-component-78c5997874-t5tsf Total loading time: 0 Render date: 2024-11-18T23:25:04.820Z Has data issue: false hasContentIssue false
  • English
  • Français

Trilobite vision: a comparison of schizochroal and holochroal eyes with the compound eyes of modern arthropods

Published online by Cambridge University Press:  08 April 2016

David Fordyce  and
Thomas W. Cronin
David Fordyce
Affiliation:
Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21228
Thomas W. Cronin
Affiliation:
Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21228
Get access Rights & Permissions [Opens in a new window]

Extract

The compound eyes of trilobites provide the best examples of fossilized sensory organs for which the function in life can be worked out today because the optical array of their corneal lenses preserves the geometry with which the eye originally sampled the visual world. An analysis of trilobite vision is strengthened by the use of new mathematical approaches to compound eye design. In particular, the product of the facet diameter (D) and the interommatidial angle (Δϕ) gives the value of the eye parameter, DΔϕ, which is a reliable indicator of the photic conditions in which the eye was used. In modern arthropods, DΔϕ values range from 0.3 for animals active in bright sunlight to 20 or more for nocturnal or deep-sea animals. Two major types of compound eyes existed in trilobites: schizochroal and holochroal. In our previous work with schizochroal eyes in the phacopids Phacops rana crassituberculata and Phacops rana milleri, we found that eye parameter values ranged from 10 to >150. These values of the eye parameter are much greater than in any living arthropod, implying that modern compound eye theory does not apply to schizochroal eyes. We suggested that each ommatidium of the schizochroal eye served as a miniature lens eye. If so, phacopid vision must have been unique, with multiply overlapping visual fields. In the new work of this paper, we examined holochroal compound eyes in Asaphus cornutus, Isotelus gigas, and Homotelus sp. Holochroal eyes contain far more ommatidia than do schizochroal types, reducing both facet diameter (D) and interommatidial angle (Δϕ). Thus, DΔϕ values in these species fall into the same range as in modern nocturnal compound eyes. This implies that function of the holochroal eye was similar to that of modern arthropods, and that they were used in moderate to dim intensities of light.

Type
Research Article
Information
Paleobiology , Volume 19 , Issue 3 , Summer 1993 , pp. 288 - 303
Copyright
The Paleontological Society 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Literature Cited

Campbell, K. S. W. 1975. The functional anatomy of phacopid trilobites: musculature and eyes. Journal and Proceedings, Royal Society of New South Wales 108:168–188.Google Scholar
Clarke, J. M. 1889. The structure and development of the visual area in the trilobite Phacops rana, Green. Journal of Morphology 2:253–270.Google Scholar
Clarkson, E. N. K. 1966a. Schizochroal eyes and vision in some phacopid trilobites. Palaeontology 9:464–487.Google Scholar
Clarkson, E. N. K. 1966b. Schizochroal eyes and vision of some Silurian acastid trilobites. Palaeontology 9:1–29.Google Scholar
Clarkson, E. N. K. 1973a. Morphology and evolution of the eye in upper Cambrian Olenidae (Trilobita). Palaeontology 16:735–763.Google Scholar
Clarkson, E. N. K. 1973b. The eyes of Asaphus raniceps Dalman (Trilobita). Palaeontology 16:425–444.Google Scholar
Clarkson, E. N. K. 1975. The evolution of the eye in trilobites. Fossils and Strata 4:7–31.Google Scholar
Clarkson, E. N. K., and Levi-Setti, R. 1975. Trilobite eyes and the optics of Des Cartes and Huygens. Nature (London) 254:663–667.CrossRefGoogle ScholarPubMed
Cronin, T. W. 1986. Optical design and evolutionary adaptation in crustacean compound eyes. Journal of Crustacean Biology 6:1–23.Google Scholar
Fordyce, D., and Cronin, T. W. 1989. Comparison of fossilized schizochroal compound eyes of phacopid trilobites with the eyes of modern marine crustaceans and other arthropods. Journal of Crustacean Biology 9:554–569.Google Scholar
Haack, S. C. 1987. The evolution and acuity of the schizochroal eye in trilobites. Evolutionary Theory 8:69–72.Google Scholar
Harrington, H. J. 1959. General description of Trilobita. Pp. O38–O117in Moore, R. C., ed. Treatise on invertebrate paleontology, part O. University of Kansas Press, Lawrence.Google Scholar
Herzog, E. D., and Barlow, R. B. 1992. The Limulus-eye view of the world. Visual Neuroscience 9:571–579.CrossRefGoogle ScholarPubMed
Horridge, G. A. 1977a. Insects which turn and look. Endeavour, New Series 1 (1):7–17.Google Scholar
Horridge, G. A. 1977b. The compound eye of insects. Scientific American 237 (7):108–120.Google Scholar
Horridge, G. A. 1978. The separation of visual axes in apposition compound eyes. Philosophical Transactions of the Royal Society of London Series B 285:1–59.Google Scholar
Land, M. F. 1980. Compound eyes: old and new optical mechanisms. Nature (London) 287:681–686.Google Scholar
Land, M. F. 1981. Optics and vision in invertebrates. Pp. 471–592in Autrum, H., ed. Handbook of sensory physiology, VII/6B. Springer, Berlin.Google Scholar
Land, M. F. 1989. Variations in the structure and design of compound eyes. Pp. 90–111in Stavenga, D. G. and Hardie, R. C., eds. Facets of vision. Springer, Berlin.Google Scholar
Meyer-Rochow, V. B. 1974. Structure and function of the larval eye of the sawfly, Perga (Hymenoptera). Journal of Insect Physiology 20:1565–1591.Google Scholar
Miller, J., and Clarkson, E. N. K. 1980. The post-ecdysial development of the cuticle and the eye of the Devonian trilobite Phacops rana milleri. Philosophical Transactions of the Royal Society of London Series B 288:461–480.Google Scholar
Nilsson, D.-E. 1989. Optics and evolution of the compound eye. Pp. 30–73in Stavenga, D. G. and Hardie, R. C., eds. Facets of vision. Springer, Berlin.Google Scholar
Packard, A. S. 1980. The structure of the eye of trilobites. American Naturalist 14:503–508.CrossRefGoogle Scholar
Serway, R. A. 1983. Physics for scientists and engineers. Saunders College Publishing, Philadelphia.Google Scholar
Snyder, A. W. 1977. Acuity of compound eyes: physical limitations and design. Journal of Comparative Physiology 116:161–182.Google Scholar
Snyder, A. W., Stavenga, D. G., and Laughlin, S. B. 1977. Spatial information capacity of compound eyes. Journal of Comparative Physiology 116:183–207.Google Scholar
Stockton, W. L., and Cowen, R. 1976. Stereoscopic vision in one eye: paleophysiology of the schizochroal eye of trilobites. Paleobiology 2:304–315.Google Scholar
Stumm, E. C. 1953. Trilobites from the Devonian Traverse Group of Michigan. Contributions from the Museum of Paleontology, University of Michigan 10:101–157.Google Scholar
Towe, K. M. 1973. Trilobite eyes: calcified lenses in vivo. Science 179:1007–1009.Google Scholar
von Campenhausen, C. 1967. The ability of Limulus to see visual patterns. Journal of Experimental Biology 46:557–5701.Google Scholar
Waterman, T. H. 1954. Directional sensitivity of the single ommatidia in the compound eye of Limulus. Proceedings of the National Academy of Sciences, U.S.A. 40:252–257.Google Scholar
Zhang, X., and Clarkson, E. N. K. 1990. The eyes of Lower Cambrian eodiscid trilobites. Palaeontology 33:911–932.Google Scholar