Meijer-Kuiper, W. (1993) Skin patterning in Octopus vulgaris and its importance for camouflage. Master's Thesis / Essay, Biology.
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Abstract
Camouflage is a method by which animals obtain concealment from other animals by blending in with their environment. Of the cephalopods, the octopods have an extra-ordinary ability to match their surroundings by changing the colour and texture of their skin. Skin patterns of the common octopus, O.vulgaris, are built up hierarchically from elements, units and components. Chronic patterns are longlasting, and are most commonly worn by Octopus; acute patterns last only seconds or minutes. Patterns are made up of components. Light and dark (chromatic) components can be distinguished, as well as components related to skin texture, or those related to posture and movement of arms, mantle, funnel, head and eyes. Components combined in series with like components and in parallel with unlike components, comprise whole patterns. At close range, Octopus skin is seen to be made up of units; patches surrounded by grooves. Papillae often arise from the centre of patches. each "chromatic unit" is made up of 3 types of elements. Most superficially lie differently coloured chromatophores; underneath these are two types of reflecting elements, reflecting cells and leucophores. Chromatophores can be expanded or retracted by their radial muscle fibres, which are under nervous control. The nervous control system is hierarchical: the paired anterior and posterior chromatophore lobes send nerves to innervate chromatophores of the head, arms and mantle. These lobes receive fibres form the paired lateral lobes which, in turn, receive fibres from the paired optic nerves, the ultimate controllers of chromatophores. Interestingly, O.vulgaris is found to be colour-blind. However, this animal is very capable of discerning differences in brightness, and this information is used to regulate the state of the chromatophores, thereby matching the tone of the surroundings. The reflector cells and leucophores (especially revealed in bright light when chromatophores are contracted) reflect incident wavelengths. The colour-blind Octopus is able to perfectly match its surroundings by actively forming a good intensity match using its chromatophores, thereby incidentally revealing a reflecting system that is able to match the background hues. Thus, if Octopus takes care of the luminance, the colour takes care of itself resulting in perfect camouflage.
| Item Type: | Thesis (Master's Thesis / Essay) |
|---|---|
| Degree programme: | Biology |
| Thesis type: | Master's Thesis / Essay |
| Language: | English |
| Date Deposited: | 15 Feb 2018 07:47 |
| Last Modified: | 15 Feb 2018 07:47 |
| URI: | https://fse.studenttheses.ub.rug.nl/id/eprint/9981 |
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