The foregoing example illustrates how visual conspicuousness and crypticity are literally in the eyes of the beholder. Detailed sensory physiology may be needed to figure out whether color patterns that appear conspicuous or cryptic to us appear that way to the animals that normally view them (for examples see Endler and Mielke 2005; Fleishman, Leal, and Sheehan 2006). A particularly nice example involves camouflage of crab spiders (Thery et al. 2005). Crab spiders make their living sitting on flowers waiting to grab bees or other pollinators that happen by. But by resting in such an exposed position, the spiders make themselves conspicuous to insectivorous birds. Clearly, they should be colored so as to be inconspicuous to both birds and bees, but this is not easy because bees and birds have different color sensitivities (see Box 3.1). Thery and colleagues (2005) collected crab spiders (Thomisus onustus) from the yellow centers of white marguerite daisies and measured the relative inten- sities of wavelengths across the spectrum, including the ultraviolet, reflected by daisy petals and centers and by crab spiders. The daylight reflectance spectra were then related to the color sensitivities of birds (blue tits, typical predators in the French meadows where the spiders were collected) and honeybees. These computations showed that the spiders’ color did not contrast sufficiently with the flower centers for them to be detected by either predator or prey. Their contrast with the petals was well above both birds’ and bees’ thresholds, which presumably selected for spiders to rest in the center. To make matters even more interesting, individuals of this species of crab spider also match their color to pink flowers, and they are similarly of low contrast to both birds and bees on this background as well (Thery and Casas 2002). To human eyes, Australian crab spiders (T. spectabilis) are cryptic on white daisies, but from a honeybees’ point of view they are highly visible because they reflect much more UV than the daisy petals. Bees are actually attracted to flowers with these UV- reflecting spiders, apparently expressing a general preference for flowers with con- trasting markings (Heiling, Herberstein, and Chittka 2003).