Long before Velcro was invented, a species of South American ant used its own natural form of the wonder material to hunt.
The claws of Azteca andreae are shaped like hooks and fit neatly into fibrous loops on the undersides of its home plants’ leaves.
It’s “like natural Velcro that is reinforced by the group ambush strategy of the workers, allowing them to capture prey of up to 13,350 times the mean weight of a single worker,” wrote researchers in a study published June 25 in PLoS One.
A. andreae colonies live in trees, and individual ants line the underside edges of leaves, jaws open and outstretched. When an insect lands, the ants seize its legs, holding it down until other ants dismember the pinioned prey.
In the new study, the researchers held weighted threads in front of the ants. Instinctively, the ants bit and held. Without losing its grip, the average worker could hold on to 8 grams, or some 5,700 times its body weight. In proportional terms, that’s like a house cat holding on to a humpback whale. Passing insects don’t have a chance.
The ants keep their grip best while on Cecropia obtusa leaves, where the surface loops are pronounced. The two species seem to have co-evolved: A. andreae provides defense against plant-munching bugs, and C. obtusa helps the ants get a predatory grip.
Another, less gruesome example of Velcro-like plant-insect interaction was recently described between bumblebees and flower petals, which have microscopic loops that enable bees to hang upside-down with little effort.
Images: 1) Azteca andreae ants aligned on a leaf, and capturing a moth./PNAS. 2) Scanning electron micrographs of hook-shaped A. andreae claw, along with top and bottom surfaces of leaves to which they cling./PNAS.
“Citation: Arboreal Ants Use the “Velcro® Principle” to Capture Very Large Prey.” By Alain Dejean, Céline Leroy, Bruno Corbara, Olivier Roux, Régis Céréghino, Jérôme Orivel, Raphaël Boulay. Public Library of Science One, Vol. 5 No. 6, June 25, 2010.