Chain Forming Leptogenys Ants from Cambodia – Stephane de Greef (2014)

The ant behavior described in these observations were first recorded by citizen scientists in Cambodia (see the original recording at the end of this post) where ants have been shown to form chains to transport large prey. The level of cooperation is so striking that myrmecologists scrambled to find out whether it is genuine. Two researchers have successfully documented the behavior by filming them in Angkor Thom, Siem Reap, Cambodia.

Self-assembling cooperation in ants is known to take many interesting forms. Weaver ants (Oecophylla spp.) ants bring leaves together by forming pulling chains while constructing their nests. Fire ants (Solenopsis spp.) congregate together to form colony rafts when there is flooding. Army ants (Eciton spp.) make bridges and ramps using their bodies to achieve speedy movement of their raiding colonies and form bivouac. Here in this short observation we see workers of the genus Leptogenys forming “daisy chains” to drag an oversized cargo after a predation event which have never been reported.

Video 4: Retrieval of various prey by Leptogenys from Stephane De Greef on Vimeo.

Body size of a worker ant is quite telling about its evolutionary adaptation to the challenges of its environment. The large workers of the Mediterranean Cataglyphis ants must solve their problems alone since the environment is too variable to leave navigational pheromone trails. Hunting a prey as big as a millipede is a challenge for such lone hunters. However, some ponerine ants are known to hunt millipedes in solitary but they never form chains after a kill.

The Leptogenys species described from Cambodia is a swarm raider. It has a narrow range of prey consisting mostly of millipedes belonging to four orders (Polydesmida, Spirostreptida, Spirobolida, Sphaerotheriida). They also attack on earthworms. Chain formation by workers enables transport of large millipedes weighing as much as 16.4 g.

Millipede predation is rare among ants for a few reasons. Millipedes are well protected due to their articulated body armor. They can defend themselves with rapid coiling motions. They also secrete potent defensive chemicals including benzoquinones, hydrogen cyanide and terpenoids. Here in this observation we can see a single 15-cm-long millipede being sieged by a swarm. The millipede gets into a defensive coil position. Soon after a worker tries to penetrate between its legs the millipede freaks out and switches into active defense by thrashing its body around. Ants swarm and paralyze the prey with a so called “rodeo-style” attack. Workers then form daisy chains with up to 52 workers grabbing gaster of their fellow workers. It appears an ant busy pulling triggers others to grab its gaster and elongate the chain. Researchers are also curious about the role of few workers grasping on to the millipede’s underside. Are they pulling or pushing or lifting? Lifting may make sense to reduce friction.

The video below is the original footage that aroused the curiosity of the biologists. We have much to learn from ants. Solutions to many Human problems like the efficient postal delivery service are solved based on Ant behavior. Ants indeed are a natural force to reckon with: