Red fluorescence in reef fish: A novel signalling mechanism?

Michiels, Nico K., Anthes, Nils, Hart, Nathan S., Herler, Jurgen, Meixner, Alfred J., Schleifenbaum, Frank, Schulte, Gregor, Siebeck, Ulricke E., Sprenger, Dennis and Wucherer, Matthias F. (2008) Red fluorescence in reef fish: A novel signalling mechanism?. BMC Ecology, 8 16: 1-14. doi:10.1186/1472-6785-8-16


Author Michiels, Nico K.
Anthes, Nils
Hart, Nathan S.
Herler, Jurgen
Meixner, Alfred J.
Schleifenbaum, Frank
Schulte, Gregor
Siebeck, Ulricke E.
Sprenger, Dennis
Wucherer, Matthias F.
Title Red fluorescence in reef fish: A novel signalling mechanism?
Formatted title

Journal name BMC Ecology   Check publisher's open access policy
ISSN 1472-6785
Publication date 2008-09-16
Year available 2008
Sub-type Article (original research)
DOI 10.1186/1472-6785-8-16
Open Access Status DOI
Volume 8
Issue 16
Start page 1
End page 14
Total pages 14
Editor Melissa Norton
Place of publication London, U.K.
Publisher BioMed Central
Language eng
Subject C1
060805 Animal Neurobiology
110906 Sensory Systems
830102 Aquaculture Fin Fish (excl. Tuna)
0608 Zoology
060299 Ecology not elsewhere classified
Formatted abstract
Background
At depths below 10 m, reefs are dominated by blue-green light because seawater selectively absorbs the longer, 'red' wavelengths beyond 600 nm from the downwelling sunlight. Consequently, the visual pigments of many reef fish are matched to shorter wavelengths, which are transmitted better by water. Combining the typically poor long-wavelength sensitivity of fish eyes with the presumed lack of ambient red light, red light is currently considered irrelevant for reef fish. However, previous studies ignore the fact that several marine organisms, including deep sea fish, produce their own red luminescence and are capable of seeing it.

Results

We here report that at least 32 reef fishes from 16 genera and 5 families show pronounced red fluorescence under natural, daytime conditions at depths where downwelling red light is virtually absent. Fluorescence was confirmed by extensive spectrometry in the laboratory. In most cases peak emission was around 600 nm and fluorescence was associated with guanine crystals, which thus far were known for their light reflecting properties only. Our data indicate that red fluorescence may function in a context of intraspecific communication. Fluorescence patterns were typically associated with the eyes or the head, varying substantially even between species of the same genus. Moreover red fluorescence was particularly strong in fins that are involved in intraspecific signalling. Finally, microspectrometry in one fluorescent goby, Eviota pellucida, showed a long-wave sensitivity that overlapped with its own red fluorescence, indicating that this species is capable of seeing its own fluorescence.

Conclusion
We show that red fluorescence is widespread among marine fishes. Many features indicate that it is used as a private communication mechanism in small, benthic, pair- or group-living fishes. Many of these species show quite cryptic colouration in other parts of the visible spectrum. High inter-specific variation in red fluorescence and its association with structures used in intra-specific signalling further corroborate this view. Our findings challenge the notion that red light is of no importance to marine fish, calling for a reassessment of its role in fish visual ecology in subsurface marine environments.


Keyword Fluorescence
Reef fishes
Guanine crystals
Eviota pellucida
Q-Index Code C1
Q-Index Status Confirmed Code

 
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Created: Tue, 31 Mar 2009, 01:51:15 EST by Shirley Rey on behalf of Faculty of Science