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Ultra-black Camouflage in Deep-Sea Fishes.

Publication ,  Journal Article
Davis, AL; Thomas, KN; Goetz, FE; Robison, BH; Johnsen, S; Osborn, KJ
Published in: Current biology : CB
September 2020

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 [1-4]. 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 [9-13]. Using finite-difference, time-domain modeling and comparisons with melanosomes found in other ectothermic vertebrates [11, 13-21], 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.

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Published In

Current biology : CB

DOI

EISSN

1879-0445

ISSN

0960-9822

Publication Date

September 2020

Volume

30

Issue

17

Start / End Page

3470 / 3476.e3

Related Subject Headings

  • Skin Pigmentation
  • Oceans and Seas
  • Melanosomes
  • Melanins
  • Fishes
  • Developmental Biology
  • Color
  • Biological Mimicry
  • Animals
  • Adaptation, Physiological
 

Citation

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Davis, A. L., Thomas, K. N., Goetz, F. E., Robison, B. H., Johnsen, S., & Osborn, K. J. (2020). Ultra-black Camouflage in Deep-Sea Fishes. Current Biology : CB, 30(17), 3470-3476.e3. https://doi.org/10.1016/j.cub.2020.06.044
Davis, Alexander L., Kate N. Thomas, Freya E. Goetz, Bruce H. Robison, Sönke Johnsen, and Karen J. Osborn. “Ultra-black Camouflage in Deep-Sea Fishes.Current Biology : CB 30, no. 17 (September 2020): 3470-3476.e3. https://doi.org/10.1016/j.cub.2020.06.044.
Davis AL, Thomas KN, Goetz FE, Robison BH, Johnsen S, Osborn KJ. Ultra-black Camouflage in Deep-Sea Fishes. Current biology : CB. 2020 Sep;30(17):3470-3476.e3.
Davis, Alexander L., et al. “Ultra-black Camouflage in Deep-Sea Fishes.Current Biology : CB, vol. 30, no. 17, Sept. 2020, pp. 3470-3476.e3. Epmc, doi:10.1016/j.cub.2020.06.044.
Davis AL, Thomas KN, Goetz FE, Robison BH, Johnsen S, Osborn KJ. Ultra-black Camouflage in Deep-Sea Fishes. Current biology : CB. 2020 Sep;30(17):3470-3476.e3.
Journal cover image

Published In

Current biology : CB

DOI

EISSN

1879-0445

ISSN

0960-9822

Publication Date

September 2020

Volume

30

Issue

17

Start / End Page

3470 / 3476.e3

Related Subject Headings

  • Skin Pigmentation
  • Oceans and Seas
  • Melanosomes
  • Melanins
  • Fishes
  • Developmental Biology
  • Color
  • Biological Mimicry
  • Animals
  • Adaptation, Physiological