Spiders That Look Like Ants

The jumping spider genus Myrmarachne (family Salticidae) has evolved bodies that closely resemble ants. This is a classic example of Batesian mimicry. Ants are highly territorial and often avoided by predators, making them an advantageous model for imitation. More than 200 species of Myrmarachne have been described, making it one of the most species-rich genera within the jumping spider family.

(a) Myrmarachne acromegalis, (b) M. cornuta, (c) M. hashimotoi, (d) M. melanocephala, (e) M. maxillosa, and (f) M. plataleoides（圖片來源：Yoshiaki Hashimoto et al，採用 CC BY 4.0 授權）

In terms of appearance, ant-mimicking spiders have an unusually elongated cephalothorax. Their first pair of legs is frequently raised and waved in the air, mimicking the antennae of ants rather than being used for walking. Their chelicerae also resemble the mandibles of ants, and in males these structures are typically even more elongated. Behaviorally, these spiders further enhance the resemblance by imitating the walking patterns of ants. Because ants commonly follow chemical trails left by nestmates, ant-mimicking spiders often move as if they are following such trails, creating the illusion that they are ordinary ants engaged in routine activity.

Myrmarachne spissa（圖片來源：Chathuri Jayatissa，採用 CC BY 4.0 授權）

What advantages come from resembling ants? Ant colonies are often avoided by other animals, as many predators hesitate to attack them for fear of retaliation. Most ant-mimicking jumping spiders do not possess particularly strong venom, and spiders are generally solitary arthropods, making them vulnerable to predators. By adopting an ant-like appearance, they can reduce the risk of predation from larger spiders, wasps, birds, and other enemies. Some ant-mimicking spiders imitate ants in a generalized way without copying a particular species, whereas others closely resemble a specific ant species. For example, Myrmaplata plataleoides closely imitates the Asian weaver ant Oecophylla smaragdina.

Although these spiders resemble ants in appearance, they do not actually integrate with the ants they mimic. They usually remain near the colonies of their model species but avoid direct contact. Their body form may be similar, yet they cannot replicate the chemical cues that ants use to recognize nestmates. If they approach too closely, the ants will quickly detect the difference and attack them.

Myrmaplata plataleoides（圖片來源：Sean.hoyland，CC0 1.0 公共領域）

Myrmarachne formosana（圖片來源：嘎嘎昆蟲網，採用 CC BY-NC-ND 4.0 授權）

Below are several ant-mimicking spider species that may be encountered in Taiwan. With a bit of luck, you might come across these convincing impostors in the wild.

Myrmarachne angusta

Myrmarachne edwardsi

Myrmarachne formosana

Myrmarachne formosicola

Myrmarachne inermichelis

Myrmarachne japonica

Myrmarachne kiboschensis

Myrmarachne sansibarica

Myrmarachne tamsuiensis

Video of Myrmaplata plataleoides:

https://www.youtube.com/watch?v=Ef2TpHHL3VI

Author: Shui-Ye You

Reference:

Hashimoto Y et al. (2020). Constraints on the jumping and prey-capture abilities of ant-mimicking spiders (Salticidae, Salticinae, Myrmarachne). Scientific Report.