If I asked you to think of the world’s most deadly predator, which species would come to mind? Maybe the cheetah, who can dart after its prey at speeds up to seventy five miles per hour? Or perhaps the great white shark, a 2,000lb monstrosity capable of tearing into its prey with a mouth full of razor sharp teeth with pressures up to 1.8 tons? It might surprise you to learn that you have probably stood face to face with one of the most efficient predators in the world today, the common dragonfly. In terms of the efficiency with which it manages to catch it’s prey, dragonflies are in fact one of the most lethal killers out there.
The dragonfly’s efficiency as a predator stems from several key attributes. Researchers have recently identified a circuit of sixteen neurons in dragonflies that connects their brains with their flight centers in the thorax, allowing them to tract and readjust their position to intercept a moving target, the way a heat seeking missile does. A dragonfly also makes good use of its visual system to actively track prey. Dragonfly eyes are some of the most acute of all insects. Furthermore, their large eyes occupy most of their heads, providing a near 360 degree field of vision. Dragonflies also make use of a neat mathematic trick in order to track and intercept their prey. Say that two objects are heading in roughly the same direction, with the second object at an angle less than fifty degrees from the direction the first object is facing. If the first object maintains this angle with the second object, the two objects must eventually collide. Dragonflies make sue of this principle by positioning and maintaining the image of their prey on a specific spot on their retina as they fly towards them. As long as the prey stays on the same retinal spot, the dragonfly is guaranteed to intercept them.
Despite their many hunting attributes, one trait in particular may set them apart from other predators. This is there ability for selective attention, something that resembles that of higher functioning organisms such as primates more than insects. A recent study in Australia looked at exactly this. The researchers used electrophysiological techniques to show the degree of selective attention in dragonflies. When presented with a single stimulus (i.e. small dot on a LCD screen), recordings from a midbrain neuron responsive to the visual stimulus elicited one pattern of firing. When presented with a different single stimulus, the same neuron would show a different characteristic pattern of firing. However, when presented with both stimuli at the same time, the neuron would show the pattern of firing characteristic of one or the other single stimulus, not a blend of the two. The researchers interpreted this as evidence for the dragonfly’s impressive selective attention abilities.
It is intriguing to ponder what we can learn from studying the mechanics of nature’s masterful little machines, such as the dragonfly. Research such as that done in the Australian study could provide us with a potential new model organism for studying selective attention as it may operate in more cognitively advanced organisms, such as humans. In addition, one of the biggest supporters of research on dragonflies is the U.S. military, who wishes to learn the secrets of one of nature’s most finely crafted aerial drones. Maybe next time you spot a dragonfly humming by outside your window, you’ll see him in a somewhat new light.
Posted by Sean McDougall (2)