Details:

Journal Title:
Current Biology
Personal Author:
Davis, Alexander L. ; Thomas, Kate N. ; Goetz, Freya E. ; Robison, Bruce H. ; Johnsen, Sönke ; ... More +
Davis, Alexander L. ; Thomas, Kate N. ; Goetz, Freya E. ; Robison, Bruce H. ; Johnsen, Sönke ; Osborn, Karen J. Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research)
Description:
At oceanic depths >200 m, there is little ambient sunlight, but bioluminescent organisms provide another light source that can reveal animals to visual predators and prey [1, 2, 3, 4]. Transparency and mirrored surfaces—common camouflage strategies under the diffuse solar illumination of shallower waters—are conspicuous when illuminated by directed bioluminescent sources due to reflection from the body surface [5, 6]. Pigmentation allows animals to absorb light from bioluminescent sources, rendering them visually undetectable against the dark background of the deep sea [5]. We present evidence suggesting pressure to reduce reflected bioluminescence led to the evolution of ultra-black skin (reflectance <0.5%) in 16 species of deep-sea fishes across seven distantly related orders. Histological data suggest this low reflectance is mediated by a continuous layer of densely packed melanosomes in the exterior-most layer of the dermis [7, 8] and that this layer lacks the unpigmented gaps between pigment cells found in other darkly colored fishes [9, 10, 11, 12, 13]. Using finite-difference, time-domain modeling and comparisons with melanosomes found in other ectothermic vertebrates [11, 13, 14, 15, 16, 17, 18, 19, 20, 21], we find the melanosomes making up the layer in these ultra-black species are optimized in size and shape to minimize reflectance. Low reflectance results from melanosomes scattering light within the layer, increasing the optical path length and therefore light absorption by the melanin. By reducing reflectance, ultra-black fish can reduce the sighting distance of visual predators more than 6-fold compared to fish with 2% reflectance. This biological example of efficient light absorption via a simple architecture of strongly absorbing and highly scattering particles may inspire new ultra-black materials.
Keywords:
[+]
General Agricultural And Biological Sciences General Biochemistry, Genetics And Molecular Biology
Source:
Current Biology, 30(17), 3470-3476.e3
DOI:
https://doi.org/10.1016/j.cub.2020.06.044
ISSN:
0960-9822
Format:
PDF
Publisher:
Elsevier BV
Document Type:
Journal Article
Funding:
Grant no. NA17OAR0110208
Rights Information:
Other
Compliance:
Library
Main Document Checksum:
[+]
urn:sha256:3cae259c3cd696327077f608c4c1af37e898601146e6caae0fe6a59b1e7463e0
Download URL:
https://repository.library.noaa.gov/view/noaa/60147/noaa_60147_DS1.pdf
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