sliaditu/. describes the condition where the upper side 

 of tlie body, exposed to the brighter illumination, is 

 heavily pigmented and the lower side of the body, 

 which is in the shadow, is lighter in color. This colora- 

 tion obliterates the effect shadows have of making a 

 body stand out from its surroundings (Thayer 1910). 

 Agcfrcssivc resemblance is where the animal closely 

 resembles some particular object rather than the gen- 

 eral environment. The Kalliiiia butterfly of the Orient 

 and the preying mantis of Central America match the 

 shape, markings, and color of leaves when the insects 

 repose with wings folded. The familiar walkingstick 

 resembles a twig. Several insect species look like 

 bird-droppings. Such resemblances doubtless serve 

 the animals to escape the attention of predators only 

 as long as they remain motionless. Even slight move- 

 ments quickly call attention to animals, regardless of 

 any concealing coloration that they may have. Be- 

 havioral orientation is well shown by those caterpil- 

 lars that are lightly colored dorsally and darkly col- 

 ored ventrally. They bring their counter-shading into 

 proper position by coming to rest upside-down along 



FIG. 13 3 Protective resemblanco 

 of an incubating ruffed grouse 

 to her surroundings (courtesy 

 U.S. Forest Service). 



FIG. 13-4 Di- 

 obscures the 



e coloration ot 

 ction between he 



1 killdeer. The white color 

 id and body. 



FIG. 13-5 Countershading. (a) the caterpillar, last instar of 

 Dicranura vinula, In normal upside-down position on a willow 

 twig in natural diffuse light. The back of this animal Is lighter 

 than the underparts. annulling the shadow, (b) the same cater- 

 pillar. Inverted, is much more conspicuous, for the countershad- 



ing effect is lost. This caterpillar has second and third lines of 

 defense: when touched, it turns a kind of grotesque "face" 

 toward you; when pressed, It squirts acid (courtesy N. Tin- 



Food and feeding relationships 193 



