title: Changeable camouflage: how well can flounder resemble the colour and spatial scale of substrates in their natural habitats?
abstract: Flounder change colour and pattern for camouflage. We used a spectrometer to measure reflectance spectra and a digital camera to capture body patterns of two flounder species camouflaged on four natural backgrounds of different spatial scale (sand, small gravel, large gravel and rocks). We quantified the degree of spectral match between flounder and background relative to the situation ofperfect camouflagein which flounder and background were assumed to have identical spectral distribution. Computations were carried out for three biologically relevant observers: monochromatic squid, dichromatic crab and trichromatic guitarfish. Our computations present a new approach to analysing datasets with multiple spectra that have large variance. Furthermore, to investigate the spatial match between flounder and background, images of flounder patterns were analysed using a custom program originally developed to study cuttlefish camouflage. Our results show that all flounder and background spectra fall within the same colour gamut and that, in terms of different observer visual systems, flounder matched most substrates in luminance and colour contrast. Flounder matched the spatial scales of all substrates except for rocks. We discuss findings in terms of flounder biology; furthermore, we discuss our methodology in light of hyperspectral technologies that combine high-resolution spectral and spatial imaging.
authors.affiliation: Marine Biological Laboratory, Bell Center, Woods Hole, MA 02543, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Oceanography and Applied Ocean Science, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
authors.forename: Derya
authors.initials: D
authors.lastname: Akkaynak
authors.affiliation: Marine Biological Laboratory, Bell Center, Woods Hole, MA 02543, USA; Coonamessett Farm Foundation, 277 Hatchville Road, East Falmouth, MA 02536, USA.
authors.forename: Liese A
authors.initials: LA
authors.lastname: Siemann
authors.affiliation: Marine Biological Laboratory, Bell Center , Woods Hole, MA 02543 , USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Barbosa
authors.affiliation: Marine Biological Laboratory, Bell Center , Woods Hole, MA 02543 , USA.
authors.forename: Lydia M
authors.identifier: 0000-0002-0603-0345
authors.initials: LM
authors.lastname: Mäthger
keywords: Paralichthys dentatus; Scophthalmus aquosus; crypsis; natural substrates; summer flounder; windowpane flounder