Photo 1. A flower crab spider (Misumena vatia) on a daisy. This species has the ability to change the colour of its body to match differently coloured surfaces. The change does not take effect quickly, as for instance in cuttlefish, but gradually, over a period of two to three days (Photo by Dinko Dorčić) Crab spider (family Thomisidae) The crab spider is characterised by its unusual crab-like appearance. Unlike other spiders, it has long front legs, a stocky body and does not spin a web to hunt prey. Crab spiders can be found on the petals of brightly coloured flowers. They are very agile, and can move quickly back and forth over the flower, as well as sideways (like a crab), a special feature of this spider. Most of the time, however, they quietly sit in ambush, waiting to grab visiting insects. Misumena vatia is one of the best-known flower crab species and, depending on the colour of the surface it is on, the spider can be either yellow (Photos 1 and 2) or white. To flying insects – the usual prey of crab spiders – brightly coloured petals are like landing strips, indicating the way to the centre of the flower or flowerhead, where a prize – nutritious pollen and sweet nectar – awaits them, providing the crab spiders, that are skilled hunters, don’t catch them first. M.R.
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