I absolutely adore the theory of evolution. It has a divine predictive, the results so wondrous in and of themselves. During my studies into symbiosis I have seen alot of strange and unusual adaptations, but the deeper I dig they more they keep getting stranger and stranger. The word this week is:

Myrmecomorphy

Top: Sandilya Theuerkauf; Bottom: Sean Hoyland (both from Wikipedia Commons).

What does this word mean? The root words myrmex means at and morphos means form. Myrmecomorphy is ant mimicking! It is a fantastic word brought to my attention recently from a paper published in the Journal of Natural History by Nelson & Jackson.

This is a form of Batesian mimicry, which occurs between two often very different species that appear very similar. The caveat is that the initial species is usually toxic, spiny or otherwise unpleasant to eat, while the mimic is a fraud and only appears to be dangerous. In the two photos at left did you spot the real ant? If you count the legs its easy to tell. The individual in the bottom photo has 8 legs whereas the top photo is the Weaver Ant, Oecophylla smaragdina, the queen nonetheless. The mimic is Myrmarachne plataleoides (female shown in photo, males have gigantic mandibles, about 33% of their body length).

The spider genus Myrmarachne (Salticidae – the jumping spiders) is characterized by these fraudulent mimics with nearly 200 species of ant wannabes, and for good reason!

“Ants are dangerous and unpalatable prey-size organisms and a variety of would-be predators of salticids, including other salticids and mantises, avoid making predatory attacks on, or coming close to, ants. Experimental studies have also shown that salticids and mantises that are averse to attacking ants are averse to attacking Myrmarachne.”

Jumping spider have complex mating behavior. Nelson & Jackson describe in detail the mating behavior of the mimics Myrmarachne assimilis and M. bakeri. Its quite the romance novel. Visualize a hot steamy jungle next to a white sand beach, a gentle breeze, seagulls laughing in the distance…

He’s alone, walking through the brush and then he sees her. The morning dew glistening off her abdomen. Her four eyes catching the sunrise to the east. He arches his palp and twitches his abdomen, standing erect. She faces him, waves her palps in the air as he watches with anticipation. She turns away, he follows. She turns around, he waits. Her cephalothorax lowers, he dances in response. She lunges past him, yet is blocked by his desire. Eight eyes are staring. She tries to leave, but his approach beckons her. His legs erect, brushing up against hers. She wants to run away, escape from these feelings, yet can’t seem to pull away. The hypnotic, primordial power of lust overcomes all her senses. She shifts her abdomen closer, he gently places his chelicerae upon her abdomen. Softly, calmly, he applies each palp once, then its over.

“When the male disengaged his applied palp, he moved over the female (her abdomen no longer raised or rotated), tapped and stroked and then, once positioned again beside the female, the male scraped his palp across her now flexed-up and rotated abdomen and resumed copulation. Before next palp application, while centered over the female, the male sometimes stepped backwards and forwards, stroking and tapping intermittently.”-Nelson & Jackson 2007

Top: Oecophylla smaragdina, Bottom: Myrmarachne plataleoides (female). Photos by Chih Fah Shin

Nelson, X., & Jackson, R. (2007). Complex display behaviour during the intraspecific interactions of myrmecomorphic jumping spiders (Araneae, Salticidae) Journal of Natural History, 41 (25), 1659-1678 DOI: 10.1080/00222930701450504