Ant-Mimicking Jumping Spider
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.
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.
There are two genera of anti-like Jumping Spiders in Singapore. The more common Mymarachne have a long waist (pedicel) and an elongated cephalothorax with a constriction dividing the higher cephalic region and the lower thoraxix part. The jaws of Myrmarachne spider, especially the males, are enormously enlarged and project in front making the spider appear to be a soldier ant.
The cephalothorax of the spiders of the genus Agorius is also divided into distinct “head” and “thoracic” regions but the division is not as obvious as that shown in Myrmarachne. The most diagnostic feature of Agorius spiders is that the first pair of legs are exceedingly long. The third last segments (patella) of the fore-legs are conspicuously more elongated than those of other spiders.