How Do Crab Spiders Change Colour?
WouterWhen a crab spider changes its colour, it does so to blend into the background. Its camouflage is useful for protecting itself against predators. However, it may not work against predators that use other senses.
In addition to blending in, a crab spider may also change its colour in order to catch prey. For example, a white crab spider may appear to match a yellow flower. But it can also pump a yellow substance into its outer layer, allowing it to revert back to white.
In contrast, some crab spiders may change their colour to attract pollinators. These spiders may choose to forage on flowers that are of their own colour, instead of the flowers of the plant they are hunting on.
Several species of spiders, including goldenrod spider Misumena vatia (Gabritschevsky 1927), change their colour in response to the presence of ultraviolet light. This is important because some spiders can reflect UV light.
Researchers at the University of Tours and CNRS in France studied the pigmentation of crab spiders. Their study revealed several interesting details about their color-changing abilities. They discovered that it took about two to six days for a crab spider to change its colour from yellow to white.
The researchers also found that it was possible to photograph crab spiders on yellow flowers. But they also noted that it was not always easy to get a good shot. One method used was to place the spider on a bright yellow flower and use an Adobe Photoshop program to take pictures.
