L The List
Myrmarachne assimilis is the only Myrmarachne species that mimics the aggressive weaver ant, with which it lives in close contact. Not only do they look alike and walk alike, it is also thought that Assimilis has developed a way to copy the chemical signatures the weavers use to recognize each other.
Amazingly, the baby spiders, when they are too minute to convincingly copy the much bigger ant species that the adult copies, use other smaller ant species as a model.
Myrmarachne melanotarsa, also called the dark-footed ant-spider, is an African jumping spider found around in Africa. This Myrmarachne mimics ants, like many other Myrmarachne, of the Crematogaster genus. However, these guys are unusual in that they exhibit social behavior, forming large communities. Hundreds of these spiders, of both sexes and of all ages, can be found in such communal nests, but most nests have between 10 and 50 spiders. It is theorized (and has been witnessed) that when Melanotarsa travels in larger groups (like ants do) they are much less likely to be attacked by specialist spiders - who actually prey on ant-mimics.
For many salticids (jumping spiders), ants can be very dangerous... but salticid eyesight seems to be up to the challenge. Some experiments have demonstrated that many species of ordinary salticids (species that are neither ant-like nor ant-eating) readily identify ants by sight and then avoid their proximity.
Ant-like and ant-eating salticids NEED to get close to ants, however, and they apparently have abilities to survive these close encounters better than other salticids. It has been thought that accurate mimics of a particular model species survive better ... but a brand new study might suggest that imperfect mimics possibly do better than their perfect couterparts.
Synemosyna formica is thought to mimic Pseudomyrmex gracilis, a nasty little a-hole that can both jump and sting.
This ant-like salticid is found from the northeastern United States southwest to Mexico. These could not look more like the super-aggressive harvester ants of the region. Specifically, note the markings on the spider's upper thorax that looks like big, bambi ant eyes.
The house I grew up in had regular infestations of these ridiculously mean little biting assholes, and I am pretty sure I would have preferred living with the spider version.
Aphanlochilus is a sly predator. Unlike many of the spiders and insects on this list, this guy looks and acts like the ants he eats. He can approach the colony without causing alarm because of his looks and his demeanor... but will strike when he gets close enough. This amazing picture (which I'm totally crediting to Alex Wild who takes stunning macros of insects & arachnids) shows Aphanlochilus rogersi holding one of its victims snatched from a column of foraging ants.
This particular spider is so specialized as a predator of these specific ants that they refuse to eat other types of insects. They not only blend in with ants by looking like them, they also hold their catches in a way that makes it look like they are just another member of the colony holding a deceased companion.
The Kerengga Ant-like Jumper mimics ant-like behaviour by the style of locomotion and by the way they wave their front legs like antennae to mimic the ants. These jumping-spiders jump only when their safety is threatened. Unlike the pissy, aggressive ants they mimic, they don't bite people.