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Other Information
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ADAPTIVE COLORATION / CAMOUFLAGE
Nearly all animals have some sort of adaptive coloration or camouflage patterning that is often linked to a behavior to make it adaptive.
Some of the functions of adaptive coloration include:
- defense against predators,
- communication with conspecifics,
- attracting or deceiving mates,
- repelling or deceiving rivals,
- signalling alarm to conspecifics and so forth,
- protection from the environment (e.g., ultraviolet radiation, cold), and
- approaching prey.
Camouflage
A primary defense against predators throughout the animal kingdom (and against the enemy during human warfare) is to avoid detection through camouflage. Achieving effective camouflage requires a suite of appropriate actions by an animal:
- sensing the local environment (including the animals in it),
- filtering the sensory input,
- using selected sensory input to make a behavior decision,
- directing the appropriate effectors (be they muscles/postures/color patterns, etc.) to achieve some form of camouflage, and
- implementing the appropriate behavior to render the camouflage effective.
How many kinds of camouflage are there?
At least six mechanisms of camouflage are recognized by biologists:
- general background resemblance,
- deceptive resemblance (including mimicry),
- disruptive coloration,
- countershading/concealment of the shadow,
- rarity through polymorphism, and
- cryptic behavior and vigilance.
Cephalopods: ultimate adaptive coloration?
A distinguishing feature of cephalopods is that individual animals can change their appearance with a speed and diversity unparalleled in the animal kingdom: we term this “rapid, neurally controlled polymorphism.” Some squids, octopuses and cuttlefish can show 30-50 different appearances. In fact, these marine invertebrates manifest most aspects of their behavior through body patterning. An example of their versatility is that – unlike other animals that use one or a few mechanisms of camouflage – cephalopods use all six mechanisms.
Sensory/motor mechanisms of achieving adaptive coloration in cephalopods
READ: How Squid Change Color
Due to their sophisticated neural control of the skin, cephalopods can adapt to a wide range of backgrounds. What sensory cues do they use to achieve background matching? Vision is probably the main cue, but cephalopods do not seem to have color vision. We are currently investigating the mechanisms and functions of polarization sensitivity in cephalopods. We have also begun to look at visual features of the background that cuttlefish use to switch on disruptive coloration.
Tactile cues seem not to be used by cuttlefish for regulating their skin texture - vision seems to be used. Olfactory cues are used by cuttlefish females to choose mates, yet we do not know if/how this translates to certain body patterns for communication.
Neural control of the complex skin has been studied at various levels in the central nervous system, particularly the lower motor centers (chromatophore lobes, lateral basal lobes).
How do you study camouflage?
Field work is mandatory to experience and understand the dynamic features of light throughout each daily, lunar, seasonal, and yearly cycle. Field work also enables observation and analysis of animal behavior under natural conditions. Laboratory experiments provide detailed testing of sensory cues, motor output and sequences of behavior. Computer simulations allow additional testing of hypotheses at multiple levels of analysis.
Recent Publications on Adaptive Coloration and Behavior:
Hanlon, R.T.; Messenger, J.B. 1996. Cephalopod Behaviour. Cambridge University Press.
Chiou, T.H., Hanlon, R.T.. Mathger, L.M., and Cronin, T.W. 2007. Spectral and spatial properties of the polarized light reflections on the arms of squid (Loligo pealeii) and cuttlefish (Sepia officinalis L.). Journal of Experimental Biology. 210: 3624-3635.
Mathger, L.M. and Hanlon, R.T. 2007. Malleable skin coloration in cephalopods: selective reflectance, transmission and absorbance of light by chromatophores and iridophores. Cell and Tissue Research 329: 179-186.
Hanlon, R.T., Conroy, L-A. and J.W. Forsythe. In press. Mimicry and foraging behavior of two tropical sand-flat octopus species off North Sulawesi, Indonesia. Biol. Journal of the Linnean Society
R. Hanlon 2007. Cephalopod dynamic camouflage. Current Biology 17 (11): 400-404. (PDF)
Hanlon, R.T., Naud, M.-J., Forsythe, J.W., Hall, K., Watson, A.C., McKechnie, J. 2007. Adaptable night camouflage by cuttlefish. American Naturalist 169 (4): 543-551. (PDF)
Barbosa, A., Mäthger, L.M., Chubb, C., Florio, C., Chiao, C.C. and Hanlon, R.T. 2007. Disruptive coloration in cuttlefish: a visual perception mechanism that regulates ontogenetic adjustment of skin patterning. Journal of Experimental Biology 210: 1139-1147. (PDF)
Mathger, L.M., Hanlon, R.T. 2006. Anatomical basis for camouflaged polarized light communication in squid. Biology Letters 2(4): 494-496. (PDF)
Chiao, C.C.; Kelman, E.J.; Hanlon, R.T. 2005. Disruptive body patterning of cuttlefish (Sepia officinalis) requires visual information regarding edges and contrast of objects in natural substrate backgrounds. Biological Bulletin. 208: 7-11.
Anderson, J.C., Baddeley, R.J., Osorio, D., Shashar, N., Tyler, C.W., Ramachandran, V.S., Cook A.C. and Hanlon, R.T. (2003) Modular organization of adaptive colouration in flounder and cuttlefish revealed by independent component analysis. Network: Comput. Neural Syst. 14: 321-333
Chiao, C.-C.; Hanlon, R.T. 2001. Cuttlefish camouflage: visual perception of size, contrast and number of white squares on artificial substrata initiates disruptive coloration. J. Exp. Biol. 204: 2119-2125..
Chiao, C.-C.; Hanlon, R.T. 2001. Cuttlefish cue visually on area—not shape or aspect ratio—of light objects in the substrate to produce disruptive body patterns for camouflage. Biol. Bull. 201:269-270.
Hanlon, R.T.; Forsythe, J.W.; Joneschild, D.E. 1999. Crypsis, conspicuousness, mimicry and polyphenism as antipredator defences of foraging octopuses on Indo-Pacific coral reefs, with a method of quantifying crypsis from video tapes. Biol. J. Linn. Soc. 66: 1-22.
Hanlon, R.T.; Maxwell, M.R.; Shashar, N.; Loew, E.R.; Boyle, K.-L. 1999. An ethogram of body patterning behavior in the biomedically and commercially valuable squid Loligo pealei off Cape Cod, Massachusetts. Biol. Bull. 197(1): 49-62.
Shashar, N; Hanlon, R.T. 1997. Squids (Loligo pealei and Euprymna scolopes) can exhibit polarized light patterns produced by their skin. Biol. Bull. 193(2): 207-208.
Forsythe, J.W.; Hanlon, R.T. 1997. Foraging and associated behavior by Octopus cyanea Gray, 1849 on a coral atoll, French Polynesia. J. Exp. Mar. Biol. Ecol. 209: 15-31.
Cornwell, C.J.; Messenger, J.B.; Hanlon, R.T. 1997. Chromatophores and body patterning in the squid Alloteuthis subulata. J. mar. biol. Assoc. U.K. 77: 1243-1246.
DiMarco, F.P.; Hanlon, R.T. 1997. Agonistic behavior in the squid Loligo plei (Loliginidae, Teuthoidea): Fighting tactics and the effects of size and resource value. Ethology 103(2): 89-108.
Adamo, S.A.; Hanlon, R.T. 1996. Do cuttlefish (Cephalopoda) signal their intentions to conspecifics during agonistic encounters? Anim. Behav. 52: 73-81.
Hanlon, R.T.; Smale, M.J.; Sauer, W.H.H. 1994. An ethogram of body patterning behavior in the squid Loligo vulgaris reynaudii on spawning grounds in South Africa. Biol. Bull. 187(3): 363-372.
Cooper, K.M.; Hanlon, R.T.; Budelmann, B.U. 1990. Physiological color change in squid iridophores II. Ultrastructural mechanisms in Lolliguncula brevis. Cell Tissue Res. 259: 15-24.
Hanlon, R.T.; Cooper, K.M.; Budelmann, B.U.; Pappas, T.C. 1990. Physiological color change in squid iridophores I. Behavior, morphology and pharmacology in Lolliguncula brevis. Cell Tissue Res. 259: 3-14.
Cooper, K.M.; Hanlon, R.T.; Budelmann, B.U. 1990. Physiological color change in squid iridophores II. Ultrastructural mechanisms in Lolliguncula brevis. Cell Tissue Res. 259: 15-24.
Novicki, A.; Budelmann, B.U.; Hanlon, R.T. 1990. Brain pathways of the chromatophore system in the squid Lolliguncula brevis. Brain Res. 519(1-2): 315-323.
Hanlon, R.T.; Wolterding, M.R. 1989. Behavior, body patterning, growth and life history of Octopus briareus cultured in the laboratory. Am. Malacol. Bull. 7(1): 21-45.
Hanlon, R.T. 1988. Behavioral and body patterning characters useful in taxonomy and field identification of cephalopods. Malacologia 29(1): 247-264.
Hanlon, R.T.; Messenger, J.B. 1988. Adaptive coloration in young cuttlefish (Sepia officinalis L.): The morphology and development of body patterns and their relation to behaviour. Phil. Trans. R. Soc. Lond. B 320: 437-487.
See also full publication list
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Octopus vulgaris camouflage change video
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