Coral Reefs

, Volume 34, Issue 3, pp 823–833 | Cite as

Fish mucus versus parasitic gnathiid isopods as sources of energy and sunscreens for a cleaner fish

  • Maxi Eckes
  • Sophie Dove
  • Ulrike E. Siebeck
  • Alexandra S. GrutterEmail author


The cleaning behaviour of the bluestreak cleaner wrasse Labroides dimidiatus is extensively used as a model system for understanding cooperation. It feeds mainly on blood-sucking gnathiid isopods and also on the epidermal mucus of client fish; the nutritional quality of these foods, however, is unknown. The epidermal mucus of reef fish contains ultraviolet (UV)-absorbing compounds (mycosporine-like amino acids, MAAs), which are only obtained via the diet; nevertheless, while La. dimidiatus has high amounts of MAAs in its mucus, their source is unknown. Therefore, the energetic value (calories and protein estimated using carbon and nitrogen) and MAA level in gnathiids and mucus from several clients [parrotfishes, wrasses (Labridae), and a snapper (Lutjanidae)] were determined. The energetic value of mucus and gnathiids varied among fishes. Overall, carbon, nitrogen, calories, and protein per dry weight were higher in the mucus of most client species compared to gnathiids. Thus, depending on the client species, mucus may be energetically more advantageous for cleaner wrasse to feed on than gnathiids. UV absorbance, a confirmed proxy for MAA levels, indicated high MAA levels in mucus, whereas gnathiids had no detectable MAAs. This suggests that La. dimidiatus obtain MAAs from mucus but not from gnathiids. Hence, in addition to energy, the mucus of some clients also provides La. dimidiatus with the added bonus of UV-absorbing compounds. This may explain why cleaner fish prefer to feed on mucus over gnathiid isopods. The likely costs and benefits to clients of the removal of UV protecting mucus and parasitic gnathiids, respectively, and the variation in benefits gained by cleaner fish from feeding on these foods may explain some variation in cooperation levels in cleaning interactions.


Mycosporine-like amino acids (MAA) Fish mucus Cleaning behaviour Ultraviolet (UV) absorbance UV protection Calories 



Thanks to J. Fenton, L. Curtis, and T. Byrne for their field assistance. Sirada Oratanachai helped with formatting of the manuscript. Staffs of Lizard Island Research Station, a facility of the Australian Museum, are greatly appreciated for their help. This work was funded by a Seaworld Research and Rescue Foundation award (ME), the ARC Centre of Excellence for Coral Reef Studies (SD), and The University of Queensland Foundation Research Excellence Award (ASG). This study was conducted under the approval of The University of Queensland Ethics Committee.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Maxi Eckes
    • 1
  • Sophie Dove
    • 1
    • 2
  • Ulrike E. Siebeck
    • 3
    • 4
  • Alexandra S. Grutter
    • 1
    Email author
  1. 1.School of Biological SciencesThe University of QueenslandSt. LuciaAustralia
  2. 2.ARC Centre for Excellence in Coral Reef StudiesThe University of QueenslandSt. LuciaAustralia
  3. 3.Sensory Neurobiology Group, School of Biomedical SciencesThe University of QueenslandSt. LuciaAustralia
  4. 4.Global Change Institute and Visual Neuroethology group, SBMSThe University of QueenslandSt. LuciaAustralia

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