Camouflage of Predatory Crab Spiders on Flowers and the Colour Perception of Bees (Aranida: Thomisidae / Hymenoptera: Apidae)

Abstract

The crab spider species Misumena vatia (Clerck 1757) can match its colour to the flowers it preys on. It can reversibly change between the colours white and yellow. For the first time, the spectral reflectance functions (including the ultraviolet) of such spiders are measured, and compared with the flowers on which they wait for prey. The bee-subjective similarity of the predators with their flowers is assessed using a model of colour vision for bees. While spiders are well matched to white flowers, the colour similarity between spiders and yellow flowers is not perfect. The UV-absorbing spiders often present themselves on UV-reflecting yellow flowers. From longer distances or for smaller flowers, however, bees may use only their green receptors, and spiders may therefore be well camouflaged. Also, spiders do not necessarily catch insects on the very flowers on which they sit; they sometimes move rapidly within respective infloresences.