Polarization sensitivity as a contrast enhancer in pelagic predators: Lessons from in situ polarization imaging of transparent zooplankton

Johnsen, Sonke, Marshall, N. Justin and Widder, Edith A. (2011) Polarization sensitivity as a contrast enhancer in pelagic predators: Lessons from in situ polarization imaging of transparent zooplankton. Philosophical Transactions of the Royal Society of London: Biological Sciences, 366 1565: 655-670. doi:10.1098/rstb.2010.0193


Author Johnsen, Sonke
Marshall, N. Justin
Widder, Edith A.
Title Polarization sensitivity as a contrast enhancer in pelagic predators: Lessons from in situ polarization imaging of transparent zooplankton
Formatted title
Polarization sensitivity as a contrast enhancer in pelagic predators: Lessons from in situ polarization imaging of transparent zooplankton
Journal name Philosophical Transactions of the Royal Society of London: Biological Sciences   Check publisher's open access policy
ISSN 0962-8436
1471-2970
Publication date 2011-03-12
Sub-type Article (original research)
DOI 10.1098/rstb.2010.0193
Volume 366
Issue 1565
Start page 655
End page 670
Total pages 16
Editor Justin Marshall
Thomas W. Cronin
Martin F. Wehling
Place of publication London, United Kingdom
Publisher The Royal Society Publishing
Collection year 2012
Language eng
Abstract Because light in the pelagic environment is partially polarized, it has been suggested that the polarization sensitivity found in certain pelagic species may serve to enhance the contrast of their transparent zooplankton prey. We examined its potential during cruises in the Gulf of Mexico and Atlantic Ocean and at a field station on the Great Barrier Reef. First, we collected various species of transparent zooplankton and micronekton and photographed them between crossed polarizers. Many groups, particularly the cephalopods, pelagic snails, salps and ctenophores, were found to have ciliary, muscular or connective tissues with striking birefringence. In situ polarization imagery of the same species showed that, while the degree of underwater polarization was fairly high (approx. 30% in horizontal lines of sight), tissue birefringence played little to no role in increasing visibility. This is most likely due to the low radiance of the horizontal background light when compared with the downwelling irradiance. In fact, the dominant radiance and polarization contrasts are due to unpolarized downwelling light that has been scattered from the animal viewed against the darker and polarized horizontal background light. We show that relatively simple algorithms can use this negative polarization contrast to increase visibility substantially.
Keyword Polarization sensitivity
Camouflage
Zooplankton
Transparency
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Theme issue 'New directions in biological research on polarized light'

Document type: Journal Article
Sub-type: Article (original research)
Collections: Queensland Brain Institute Publications
Official 2012 Collection
 
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Created: Fri, 11 Nov 2011, 16:33:44 EST by Debra McMurtrie on behalf of Queensland Brain Institute