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Encyclopedia > Countershading
Countershading employed by the grey reef shark.
Countershading employed by the grey reef shark.
Anolis caroliensis showing blending camouflage and countershading.
Anolis caroliensis showing blending camouflage and countershading.
Countershading in caterpillars.
Countershading in caterpillars.
Countershading in Eyed hawkmoth larvae.

Countershading, or Thayer’s Law, is a form of camouflage. Countershading, in which an animal’s pigmentation is darker dorsally, is often thought to have an adaptive effect of reducing conspicuous shadows cast on the ventral region of an animal’s body. In essence the distribution of light on objects that are lit from above will cause unequal reflection of light on a solid body of uniform colour, such shadows could provide predators with visual cues to a prey's shape and projection. Countershading therefore, reduces the ease of detection of prey by potential predators by counterbalancing the effects of shadowing. Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... Binomial name Carcharhinus amblyrhynchos (Bleeker, 1856) The Gray Reef Shark (Carcharhinus amblyrhynchos) is one of the most common sharks found around coral reefs of Indo-Pacific waters. ... Carolina anole Photo by Pollinator, on goldenrod, South Carolina, October, 2001 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Carolina anole Photo by Pollinator, on goldenrod, South Carolina, October, 2001 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Binomial name Anolis carolinensis Linnaeus, 1758 Subspecies Anolis carolinensis carolinensis Anolis carolinensis seminolus The Carolina Anole (Anolis carolinensis), also known as the Green Anole, is an arboreal lizard found primarily in the southeastern parts of the United States and some Caribbean islands. ... Image File history File links Size of this preview: 440 × 600 pixel Image in higher resolution (887 × 1209 pixel, file size: 837 KB, MIME type: image/jpeg) h rowland This image is in the public domain in the United States. ... Image File history File links Size of this preview: 440 × 600 pixel Image in higher resolution (887 × 1209 pixel, file size: 837 KB, MIME type: image/jpeg) h rowland This image is in the public domain in the United States. ... Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... An infant Cuttlefish blends into the surrounding sand substrate. ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ...


Countershading is observed in a variety of animals: pronghorn antelope, White-tailed deer, squirrels, birds, and various lepidiopteran larvae. Binomial name Antilocapra americana Ord, 1815 The pronghorn (Antilocapra americana) is the only surviving member of the family Antilocapridae, and the fastest land animal in North America running at speeds up to 54 mph (90 km/h). ... Binomial name Odocoileus virginianus Zimmermann, 1780 The White-tailed deer (Odocoileus virginianus), also known as the Virginia deer, is a medium-sized deer found throughout most of the continental United States, southern Canada, Mexico, Central America and northern portions of South America as far south as Peru. ... Genera Several, see text Squirrel is the common name for rodents of the family Sciuridae. ...


Alternatively, in many marine animals (including various species of fish, particularly sharks, and cephalopods) this form of camouflage may work through background matching; when seen from the top, the darker dorsal area of the animal blends into the darkness of the water below, when seen from below, the lighter ventral area blends into the sunlight from the surface. A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... Orders Carcharhiniformes Heterodontiformes Hexanchiformes Lamniformes Orectolobiformes Pristiophoriformes Squaliformes Squatiniformes Symmoriida(extinct) Sharks (superorder Selachimorpha) are fish with a full cartilaginous skeleton[1] and a streamlined body. ... Orders Subclass Nautiloidea †Plectronocerida †Ellesmerocerida †Actinocerida †Pseudorthocerida †Endocerida †Tarphycerida †Oncocerida †Discosorida Nautilida †Orthocerida †Ascocerida †Bactritida Subclass †Ammonoidea †Goniatitida †Ceratitida †Ammonitida Subclass Coleoidea †Belemnoidea †Aulacocerida †Belemnitida †Hematitida †Phragmoteuthida Neocoleoidea (most living cephalopods) Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida The cephalopods (Greek plural (kephalópoda); head-foot) are the mollusk class Cephalopoda... In anatomy, the dorsum is the upper or back side of an animal, as opposed to the ventrum. ...


Furthermore, countershading could also result from differential selection pressures on dorsal and ventral surfaces, from the need to protect against the damaging properties of UV light, or abrasion.

The original drawings from Thayer's patent application, 1902.
The original drawings from Thayer's patent application, 1902.

Abbott Handerson Thayer was one of the first to conduct extensive research on and to write about certain aspects of protective colouration in nature. In 1892, he wrote about the function of countershading in nature, in which he accounted for the white undersides of animals. For this reason countershading is sometimes called Thayer’s Law. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A Virgin, painted allusion to Winged Victory of Samothrace Abbott Handerson Thayer (August 12, 1849 – 1921), American artist, was born at Boston, Massachusetts. ...


Military camouflage sometimes uses the same principle; Thayer even obtained a patent in 1902 to paint warships using a countershaded scheme. Camouflage became an essential part of modern military tactics after the increase in accuracy and rate of fire of weapons at the end of the 19th century. ...


Countershading research as a means of education

The Australian education authority has initiated a scheme whereby members of the public can become involved in research trying to determine if countershading enhances camouflage. media:pastry prey and countershading.pdf


References

  • Edmunds, M. & R.A. Dewhirst (1994). The survival value of countershading with wild birds as predators. Biological Journal of the Linnean Society 51(4): 447-452.
  • Ruxton, G.D., M.P. Speed & D.J. Kelly (2004). What, if anything, is the adaptive function of countershading? Animal Behaviour 68(3): 445-451.
  • Speed, M.P., D.J. Kelly, A.M. Davidson, G.D. Ruxton(2005). Countershading enhances crypsis with some bird species but not others. Behavioral Ecology 16(2): 327-334.
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  Results from FactBites:
 
The Ocean Channel > How does countershading help fish in the ocean? (136 words)
Countershading is a type of camouflage used by open ocean fish and mammals, like tuna, sharks, and dolphins.
When predators are above them, they see the dark blue, which blends into the ocean below; when predators are below them, the light undersides blend in with the brightness of the water near the surface.
Using countershading, open ocean fish and mammals are able to escape the attention of their predators.
  More results at FactBites »

 
 

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