This is not an ant - it's a spider
Next time you see an ant, count its legs because you might really be looking at a spider. And this isn't a rare phenomenon - scientists have found that as many as 300 spider species around the world mimic ants.
Spiders like Myrmarachne melanotarsa, a jumping spider, will hang out with ants and adopt ant behavior to blend in - and they do it to scare away predators. That may seem counter-intuitive to us since more people have arachnophobia than myrmecophobia (ant-phobia), but it turns out that many spiders and spider predators are terrified of ants.
“Ants are very dangerous to arthropods,” Ximena Nelson, of the University of Canterbury, told Discovery News. "Many ants contain formic acid, which they can use for defense by squirting it on potential predators, causing considerable harm.”
These strategies, which were selected by evolution over time, are not like most forms of animal mimicry, where an animal might temporarily mimic a sound or camouflage itself. "Each morph that resembled ants more was selected for and morphs that did not resemble ants were selected against,” added Nelson.
So for many spiders, being disguised as an ant is the perfect defense strategy. They use their front legs as pretend antennae, reflective hairs to look shiny, and a false waist.
But for some spider species, an ant disguise is ideal for sneaking up on an unsuspecting ant and eating it. These spiders tend to attack stray ants so they don't get attacked by a mass of ants. Some spiders use their ant-look to turn the tables on their predators and feast on their predators' eggs.
So not only is the disguise a good way to not get eaten, it's also useful to carry out a stealth attack.