In our principal components analysis (PCA) of cuttlefish, body pattern principal components (PCs) often approximate body patterns identified by Hanlon and his co-workers ( Hanlon and Messenger, 1988 Mäthger et al., 2006). (C) Some of these components numbered according to the scheme proposed by Hanlon and Messenger ( Hanlon and Messenger,1988) (see Fig. 3A for further body patterns)( Mäthger et al., 2006 Kelman et al., 2007). between pebbles) appears to affect the overall contrast in the body pattern rather than the relative strengths of disruptive and mottle patterns (see Fig. The level of visual contrast within the image (e.g. Increasing pebble size would cause the animal to emphasise components associated with the disruptive pattern, and decreasing pebble size would favour the mottle. (B) A juvenile cuttlefish ( Sepia officinalis) settled amongst pebbles, which is displaying components that are characteristic of both the disruptive and mottle body patterns. The animals also illustrate a range of skin textures. From left to right the animals illustrate: a pale uniform pattern a stipple with some mottle a mottle with weak disruptive elements and a high contrast pattern(but not typically disruptive). (A) Examples of four camouflage patterns from juvenile cuttlefish (mantle length 50 mm). The fact that some clusters found by Crook and co-workers did not correspond to recognised body patterns emphasises the difficulty inherent in classifying such high-dimensional image data by eye.Ĭuttlefish coloration patterns and their components. Nonetheless, when Crook and co-workers ( Crook et al.,2002) used cluster analysis to investigate the expression of behavioural components in some 800 images of juvenile cuttlefish taken in diverse behavioural contexts (from a laboratory aquarium) they found the same number of clusters (13), several of which corresponded to the body patterns recognised by Hanlon and Messenger ( Hanlon and Messenger, 1988). This flexibility allows a vast range of patterns, and means that the classification of the principal body patterns is somewhat subjective. Just as we can combine surprise with fear or happiness, the cuttlefish mix their body patterns, and also modulate the strengths of the behavioural components separately. Hanlon and Messenger ( Hanlon and Messenger,1988) proposed that cuttlefish can similarly co-ordinate their behavioural components to give 13 basic body patterns. To conclude we argue that the visual strategy cuttlefish use to select camouflage is fundamentally similar to human object recognition.Ĭephalopod behavioural components can be compared to human facial signals,such as a smile or a frown, which are co-ordinated to produce basic expressions of happiness, fear, surprise and so forth( Ekman et al., 2002). We suggest that they use several visual cues to `identify' this type of background (including: edges, contrast, size,and real and pictorial depth). Naturally, cuttlefish probably use the disruptive pattern amongst discrete objects, such as pebbles. Here we show that visual depth is also relevant. On 2-D backgrounds, isolated pale objects of a specific size, that have well-defined edges, elicit the disruptive pattern. One can also ask what features in the visual environment elicit a given coloration pattern here most work has been on the disruptive body pattern, which includes well-defined light and dark features. We have, for instance, tested their sensitivity to image parameters including spatial frequency, orientation and spatial phase. This behaviour has great flexibility, allowing the animals to produce a very large number of patterns, and hence gives unique access to cuttlefish visual perception. They produce the appropriate pattern for a given environment by co-ordinated expression of about 40 of these`chromatic components'. Cuttlefishes of the genus Sepia produce adaptive camouflage by regulating the expression of visual features such as spots and lines, and textures including stipples and stripes.
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