Some Jumping Spiders assume the appearance of an ant by having long and slender legs and what appears to be a three-part (head-thorax-abdomen) body of an insect. To add further to the deception, the fore-legs are often raised in the air like a pair of antennae.
(Dairy Farm Nature Park - 11 Nov 2009)
Some scientists believe that by mimicking ants, the spiders deceive their ant-models and prey either on the ants themselves, or on the homopteran bugs "tended" by the ants. However, it should be noted that the ant-mimicking Jumping Spiders in Singapore have never been observed to have attacked the ants they imitate. A more plausible explanation is that by copying the physical appearance of ants, the ant-mimicking Jumping Spiders are actually buying insurance for self-protection, since spider-hunting wasps, birds and other spider-predators generally avoid ants which secrete the distasteful formic acid when attacked.