title: Open-ocean fish reveal an omnidirectional solution to camouflage in polarized environments.
abstract: Despite appearing featureless to our eyes, the open ocean is a highly variable environment for polarization-sensitive viewers. Dynamic visual backgrounds coupled with predator encounters from all possible directions make this habitat one of the most challenging for camouflage. We tested open-ocean crypsis in nature by collecting more than 1500 videopolarimetry measurements from live fish from distinct habitats under a variety of viewing conditions. Open-ocean fish species exhibited camouflage that was superior to that of both nearshore fish and mirrorlike surfaces, with significantly higher crypsis at angles associated with predator detection and pursuit. Histological measurements revealed that specific arrangements of reflective guanine platelets in the fish's skin produce angle-dependent polarization modifications for polarocrypsis in the open ocean, suggesting a mechanism for natural selection to shape reflectance properties in this complex environment.
authors.affiliation: Department of Integrative Biology, University of Texas, Austin, TX 78712, USA.
authors.forename: Parrish C
authors.initials: PC
authors.lastname: Brady
authors.affiliation: Optical Remote Sensing Laboratory, the City College of New York-CUNY, New York, NY 10031, USA.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Gilerson
authors.affiliation: Department of Physics and Astronomy and Institute for Quantum Science and Engineering, Texas A&M University, College Station, TX 77843-4242, USA.
authors.forename: George W
authors.initials: GW
authors.lastname: Kattawar
authors.affiliation: Harbor Branch Oceanographic Institute, Florida Atlantic University, Ft. Pierce, FL 34946, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Sullivan
authors.affiliation: Harbor Branch Oceanographic Institute, Florida Atlantic University, Ft. Pierce, FL 34946, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Twardowski
authors.affiliation: Department of Marine Sciences, University of Connecticut Avery Point, 1080 Shennecossett Road, Groton, CT 06340-6048, USA.
authors.forename: Heidi M
authors.initials: HM
authors.lastname: Dierssen
authors.affiliation: Department of Physics and Astronomy and Institute for Quantum Science and Engineering, Texas A&M University, College Station, TX 77843-4242, USA.
authors.forename: Meng
authors.initials: M
authors.lastname: Gao
authors.affiliation: Department of Integrative Biology, University of Texas, Austin, TX 78712, USA.
authors.forename: Kort
authors.initials: K
authors.lastname: Travis
authors.affiliation: Department of Integrative Biology, University of Texas, Austin, TX 78712, USA.
authors.forename: Robert Ian
authors.initials: RI
authors.lastname: Etheredge
authors.affiliation: Optical Remote Sensing Laboratory, the City College of New York-CUNY, New York, NY 10031, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Tonizzo
authors.affiliation: Optical Remote Sensing Laboratory, the City College of New York-CUNY, New York, NY 10031, USA.
authors.forename: Amir
authors.initials: A
authors.lastname: Ibrahim
authors.affiliation: Optical Remote Sensing Laboratory, the City College of New York-CUNY, New York, NY 10031, USA.
authors.forename: Carlos
authors.initials: C
authors.lastname: Carrizo
authors.affiliation: Optical Remote Sensing Laboratory, the City College of New York-CUNY, New York, NY 10031, USA.
authors.forename: Yalong
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Department of Marine Sciences, University of Connecticut Avery Point, 1080 Shennecossett Road, Groton, CT 06340-6048, USA.
authors.forename: Brandon J
authors.initials: BJ
authors.lastname: Russell
authors.affiliation: Department of Integrative Biology, University of Texas, Austin, TX 78712, USA.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Mislinski
authors.affiliation: Department of Integrative Biology, University of Texas, Austin, TX 78712, USA.
authors.forename: Shulei
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Department of Integrative Biology, University of Texas, Austin, TX 78712, USA.
authors.forename: Molly E
authors.initials: ME
authors.lastname: Cummings
mesh_terms: D000818:Animals; D000067558:Biological Mimicry; D001792:Blood Platelets / Q000166:cytology; D017753:Ecosystem; D005399:Fishes / Q000502:physiology*; D009792:Oceans and Seas; D011235:Predatory Behavior; D012641:Selection, Genetic; D012867:Skin / Q000033:anatomy & histology / Q000098:blood supply; D014785:Vision, Ocular