Barbosa Alexandra

No Thumbnail Available
Last Name
Barbosa
First Name
Alexandra
ORCID

Filters

2010 - 2017 2
2
2
Reset filters

Settings

Search Results

Now showing 1 - 2 of 2
  • Article
    A “mimic octopus” in the Atlantic : flatfish mimicry and camouflage by Macrotritopus defilippi
    (Marine Biological Laboratory, 2010-02) Hanlon, Roger T. ; Watson, Anya C. ; Barbosa, Alexandra
    The sand-dwelling octopus Macrotritopus defilippi was filmed or photographed in five Caribbean locations mimicking the swimming behavior (posture, style, speed, duration) and coloration of the common, sand-dwelling flounder Bothus lunatus. Each species was exceptionally well camouflaged when stationary, and details of camouflaging techniques are described for M. defilippi. Octopuses implemented flounder mimicry only during swimming, when their movement would give away camouflage in this open sandy habitat. Thus, both camouflage and fish mimicry were used by the octopuses as a primary defense against visual predators. This is the first documentation of flounder mimicry by an Atlantic octopus, and only the fourth convincing case of mimicry for cephalopods, a taxon renowned for its polyphenism that is implemented mainly by neurally controlled skin patterning, but also—as shown here—by their soft flexible bodies.
  • Article
    Changeable camouflage : how well can flounder resemble the colour and spatial scale of substrates in their natural habitats?
    (Royal Society, 2017-03-08) Akkaynak, Derya ; Siemann, Liese A. ; Barbosa, Alexandra ; Mathger, Lydia M.
    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 of perfect camouflage in 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.