MIMICRY IS a strategy for survival. By resembling and even behaving like unpalatable or dangerous ant species, some spiders in ant's clothing minimise the chance of being eaten by predators. Of course, the casual observer who chances upon these spiders would dismiss them as ants.
 Several of these ant-mimics are jumping spiders (family Salticidae) belonging to the genus Myrmarachne. So far, I have photographed one species, the Kerengga Ant-like Jumper (Myrmarachne plataleoides).
 As the name indicates, it is a mimic of the kerengga or weaver ant (Oecophylla smaragdina). Weaver ants need no introduction (for initiated MNS members, anyway) as they have long acquired a certain notoreity.
 Readers who have yet to cross their path (quite unlikely as weaver ants are a common species found in plantations, orchards, gardens, and the belukar or forest fringe), should know that they have no fear of humans and attack without hestitation.
 They have sharp and strong pincer-like mandibles, or jaws. As they bite, they discharge irritating secretions from mandibular glands which intensify the pain they inflict on anyone who comes into body contact with them. They also release formic acid, another irritant, from their gaster or abdomen.
 The combined effects of the powerful pinch and chemical cocktail often linger on for a couple of days.
 The Kerengga Ant-like Jumper is the same size, shape and colour of its model. The spider also walks like the weaver ant and only jumps when its safety is threatened. However, unlike the weaver ant, M. plataleoides does not bite people, and indeed seem rather timid.
 The spider can only be found in trees or bushes where weaver ants live in long-established colonies. Not many people would want to muck around in a bush crawling with kerengga, and that's one good reason why the spider is seldom seen.
 After reading about M. plataleoides some years ago, I began looking out for this amazing ant-mimicking arachnid and eventually found a male specimen in my old kampong in Kulim, Kedah. I managed to take some pictures, but not without first suffering the wrath of the weaver ants for intruding into their territory (a long-neglected starfruit tree).
 Subsequently, I found several more ~ male, female and juvenile ~ on an old mango tree nearby. Weaver ants have made this tree their home for many years. Because they keep away other insects and pests, we have been getting regular harvests of the fruit.
 Predators such as birds, lizards and frogs avoid weaver ants not only because of their ferocious nature but also because they taste terrible due to the formic acid they discharge when molested.
 How does a spider, an arachnid with two body segments and eight legs, manage to look like an ant, an insect with three body segments and six legs?
 By developing several constrictions around the cephalothorax and abdomen, M. plataleoides creates the illusion of having the distinct head, thorax and gaster of the weaver ant, complete with a long and slender waist.
 Two black patches on the head mimic the weaver ant's large compound eyes. These patches hide real eyes ~ the tiny posterior-lateral eyes. Like other jumping spiders, M. plataleoides has four pairs of eyes, the largest being the anterior-median eyes (but so far I could make out only three pairs). As a final touch to the disguise, the spider often holds up its two front legs like a pair of antennae.
 The female Kerengga Ant-like Jumper is a nearly perfect copy of the weaver ant, but not the male. His disguise is somewhat marred by a very prominent protuberance on the front of the head. Protruding by about half the length of his body, it looks like the nose of an arthropod Pinnochio that has just told a big lie. (Another writer says this long "nose" makes him seem a benign character ~ like the poet Cyrano de Bergerac.)
 This "nose" is in fact a pair of chelicerae (jaws bearing sabre-like fangs) which are normally held together. These oversized chelicerae are a second sexual characteristic which develops during the male spider's final moult when it turns into an adult.

 They are also a symbol of male dominance. Like the antlers of stags battering it out for domination during the rutting season, these fangs are used in duels with rival males for the opportunity to mate with a female. The one with the more impressive member usually wins.
 These fights rarely end in death. The defeated male backs away and scuttles off. The battle over, the spiders retract their fangs into the chelicerae.
 These fangs are also used for killing prey. Spiders normally paralyse their prey by injecting them with venom through ducts inside their fangs. The spiders suck up the liquefied food when digestive enzymes from the stomach have acted on the tissues of their victims.
 However, due to the exaggerated length of their fangs, M. plataleoides males have lost the ability to inject venom to immobilize prey. They resort to the less elegant method of holding down the prey and stabbing it with their fangs.
 Also because of their unwieldy chelicerae, feeding is a messy business for the male spiders. They have to stab their prey repeatedly in order to suck up nutrients through the holes.
 An arachnologist who studied M. plataleoides on Mount Mikiling in the Philippines says the huge chelicerae do not make the male spiders any less ant-like. According to him, the male's appearance resembles a larger weaver ant carrying a smaller one (in its mouth). Weaver ant workers which forage for food are larger than those which care for eggs and larvae inside the nest. The larger workers often transport the smaller ones between different parts of an extended weaver ant colony, he observes.
 Despite the less-than-perfect disguise of the male, the deception employed by M. plataleoides has generally succeeded and enabled the species to gain a special though somewhat precarious niche within the weaver ant's territory.
 It is believed that the spiders are able to produce pheromones, or chemical scents, to trick the weaver ants into accepting them as members of their colony.
 Perhaps, as an extra precaution, the spiders avoid any contact with weaver ants. On several occasions, I have seen solitary spiders running away to hide under a leaf when some exploring weaver ants got too close for comfort.
 These ant-mimicking spiders are fascinating creatures. I am currently on the lookout for other species such as the Giant Ant-like Jumper (Myrmarachne maxillosa) which resembles the common spiny ants of the genus Polyrhachis.
 Another weaver ant mimic is the Ant-like Crab Spider (Amyciaea lineatipes) of the family Thomisidae. This is an insidious species; it preys on the weaver ants at night.
 The literature on these ant-mimicking spiders is apparently quite limited. Although small in number and seldom seen, these creatures are an interesting part of our natural fauna. They deserve some attention from our biologists and naturalists.
 (This article was published in the Malayan Naturalist, Vol 51 No. 1, August 1997, under the heading "Amazing: Spider Mimics Ants".)
  * The weaver ants have since disappeared from that old mango tree. About a year after this article was published, I returned to my hometown and found all the ant nests gone. So were the ant-mimicking spiders. I asked my folks in Kulim if they had done anything to get rid of the kerengga. They said no. They just disappeared mysteriously.

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