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Comparative Morphology of the Eye (with Particular Attention to the Retina) in Various Species of Cardinal Fish (Apogoni

Comparative Morphology of the Eye (with Particular Attention to the Retina) in Various Species of Cardinal Fish (Apogonidae, Teleostei).

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Comparative Morphology of the Eye (with Particular Attention to the Retina) in Various Species of Cardinal Fish (Apogoni

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  1. Comparative Morphology of the Eye (with Particular Attention to the Retina) in Various Species of Cardinal Fish (Apogonidae, Teleostei) Fishelson, L., Ayalon, G., Zverdling, A., Holzman, R. 2004. Comparative Morphology of the Eye (with Particular Attention to the Retina) in Various Species of Cardinal Fish (Apogonidae, Teleostei). The Anatomical Record 271A: 249-261.

  2. Background Information: • Class: Actinopterygii • Ray-finned fishes • Order: Perciformes • Perch-like • Family: Apogonidae • Cardinal fish

  3. Apogonidae • Approximately 300 species • Diurnal or Nocturnal • Warm-water seas • Shallow waters • Benthic • Feed on small prey and plankton

  4. Apogon cookii Apogon angustatus Apogon coccineus Apogon annularis

  5. In past studies: • Diurnal species • Retinas contain more cones in the cone/rod ratio • Nocturnal species • Retinas contain more rods in the cone/rod ratio • Reasoning: • Cones enable the eye to adapt to various intensities of UV-light • Rods adjust to enhance vision at low light or during darkness

  6. Objectives: • To compare the eyes, particularly the retinas, of several species of cardinal fish • Observe differences in the retinas of diurnal and nocturnal cardinal fish C. quinquelineatus

  7. Methods: • Most fish were observed and collected along reefs of the Red Sea and Mombassa, Kenya • The fish were taken to a laboratory where they were injected with an overdose of MS 222 (anesthetic for aquatic wildlife) • Body length measurements were taken for comparisons • Eyes removed, measured, dissected, examined under microscopes • Total of 140 eyes from 110 fish representing 15 species

  8. Results and Discussion: • Compared to past research, the eyes of the cardinal fish are much larger than other perciforms in comparison to total body length. • As cardinal fish grow in size, their eyes grow as well • Nocturnal cardinal fish have higher eye diameter per total length than diurnal cardinal fish

  9. Results and Discussion: • As cardinal fish grow in size, their %ED/TL decreases • This decrease occurs less in the small nocturnal fish than the diurnal fish

  10. Results and Discussion: • The larger the eye, the larger the retina • More visual cells in the smaller, nocturnal fish than the larger diurnal fish • ex.) A. fucata, 68mm TL – 562,500 visual cells • ex.) C. lineatus, 180mm TL – 155,560 visual cells

  11. Results and Discussion: • The cones of the eyes do not differ significantly between the nocturnal or diurnal cardinal fish with similar retinal size • The rods differ significantly: • ex.) A. annularis 72mm TL, 150mm2 retina • ex.) Ch. lineatus, 150mm TL, 150mm2 retina

  12. Conclusions: in comparison • Nocturnal cardinal fish: • Tend to be smaller in total length • Have larger retinas per total length • Retain large retinas as total length increases • Retinas are rich in rods • Therefore, can see better in darkness or in low-lit waters • Diurnal cardinal fish: • Grow larger in total length • Retina sizes aren’t as large compared to body length • Retinas are rich in cones • Better adapted to see during the day or afternoon hours

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