Chameleon of the spiders: Misumena vatia
If you love spiders, as well as insects, then this post is just for you! HOPE for the Future Collections Assistant, Steven H. Williams, tells us about a fascinating spider with the ability to change colour; Misumena vatia, the flower spider.
Gerald Durrell wrote in his famous book: My Family and Other Animals, that he excitedly discovered little spiders that ‘could change colour just as successfully as any chameleon’. He was referring to a family of spiders commonly known as crab-spiders. Crab-spiders get their name due to the position in which they hold their front legs that resembles a crab’s claws, and their ability to walk sideways like a crab. Although we cannot be clear which species Durrell had found, we know that a colour-changing crab spider which is quite common in the southern half of Britain during May-August is Misumena vatia (the flower spider).
Only about 30 species of crab-spider can change colour, most stay as different shades of brown or green with a slight pattern on the abdomen, but some species, including our native Misumena vatia, can alter their appearance quite drastically to blend into the background.
Crab-spiders do not spin webs like orb-weaving spiders would, instead they wait, poised for action, ready to attack insects that stray into their path. Misumena vatia (the flower spider), as its common name suggests, sits on flowers ready to pounce on any insect that chooses to land near it, often hover-flies or even bumblebees. The venom inside crab-spiders is quite strong as they can kill insects much larger than themselves but don’t worry, the flower spider and all other British crab-spiders only have small jaws and cannot hurt humans!
The flower spider is mostly seen as pure white or a lemony-yellow colour with a red mark on either side of its abdomen, but it has also been found green and even faintly slate-blue.
Colour-changing crab spider with prey. Image credit: Bendix Grunlich; CC BY-SA 4.0 
Yellow crab spider. Image credit: Abijithka. CC BY-SA 4.0
The total transformation from one colour to another takes several days and it is easier to go from yellow to white than white to yellow. These spiders can choose from many different types of flowers as they easily disappear into their surroundings. The favourite flower of Misumena vatia in Britain appears to be the ox-eye daisy, but it has also been seen on ragwort, and other flowers with white or yellow petals. Only the females can make these drastic colour changes though, the males are much smaller and sadly cannot change colour.
So next time you are out exploring for insects and spiders why not see if you can spot a Misumena vatia inside a flower?
Steven H. Williams
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Crunchy on the outside 