Crab spider (Misumena vatia), SEM

Coloured scanning electron micrograph (SEM) of goldenrod crab spider (Misumena vatia). Crab spiders hide in flowers and move sideways to align themselves with their prey, hence their name. They prey on insects such as flies or bees 2 to 3 times their size. These spiders may be yellow or white, depending on the flower in which they are hunting, as they can change their colour at will. Crab spiders change colour by secreting a liquid yellow pigment into the outer cell layer of the body. On a white base, this pigment is transported into lower layers, so that inner glands, filled with white guanine, become visible. If the spider dwells longer on a white plant, the yellow pigment is often excreted. It will then take the spider much longer to change to yellow, because it will have to produce the yellow pigment first. The colour change is induced by visual feedback. Magnification: x5.3 when shortest axis printed at 25 millimetres.