Misumena vatia

These spiders may be yellow or white. This ultimately depends on the flower on which they are hunting (active camouflage). Younger females especially, which may hunt on a variety of flowers such as daisies and sunflowers, have a strong tendency to adapt to the color of the surrounding flower. However, the color-changing process is not instant and can require up to 25 days to complete. Older females need large amounts of relatively large prey to produce the best possible clutch of eggs. In North America, they are most commonly found in goldenrods, bright yellow flowers which attract large numbers of insects, particularly in autumn. It is often very hard even for a searching human to spot this spider on a yellow flower. These spiders are sometimes called 'banana spiders' because of their striking yellow color.

Females have light complexions, either white or yellow with darker sides. They may have some markings on the abdomen that can be brown or red. These markings are genetically determined and not affected by a background color change. Males are darker than females, with red or brown outer shells. They have a characteristic white spot in the middle that continues through the area around the eyes. Males specifically have two sets of red and white bands both dorsally and laterally. Similar species of the crab spiders appear in a variety of colors such as those of the genus Diaea, which can be lime green, or some species of Xysticus and Coriarchne which are brown.

These spiders change color based on visual cues. The color-change is most obvious on females of this species. The ability of males and juveniles to change color has not been documented. Two other known spiders with this color change ability include Thomisus onustus and Thomisus spectabilis. Depending on the color of flower they see around them, they can secrete a liquid yellow pigment into the body's outer cell layer. The baseline color of the spider is white. In its white state, the yellow pigment is sequestered beneath the outer cell layer so that inner glands which are filled with white guanine are visible. They are able to match with greater accuracy to white flowers, such as Chaerophyllum temulum (the rough chervil) in particular, compared to yellow flowers based on the spectral reflectance functions. While the spider is residing on a white plant, it tends to excrete the yellow pigment instead of storing it in its glands. In order to change back to yellow, the spider must first produce enough of the yellow pigment. For this reason it takes these spiders much longer to turn from white to yellow than it does for them to go from yellow to white. The color change from white to yellow can take between 10 and 25 days while the opposite color change takes only about six days. The yellow pigments are kynurenine and 3-hydroxykynurenine. Color changes are induced by visual cues and spiders with impaired vision lose this ability.

Notably, spiders of this species sometimes choose to hunt on flowers that, to the human eye, they do not appear to match in color. For instance, they can be found hunting on the pink petals of the pasture rose (Rosa carolina). The spider appears white, or changes to white, causing it to stand out to human observers. Arthropods, on the other hand, serve as both predators and prey to Misumena vatia, and have photoreceptors that allow them to see ultraviolet, blue, and green light but oftentimes lack red receptors altogether. As a result, Misumena vatia is camouflaged, appearing dark on a dark background.