Wednesday, April 3, 2013

Nature's Most Deadly Predator

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)


  1. Who would have thought the dragon fly to be the greatest predator. Very interesting to learn that the military is studying their flight patterns and trying to manipulate them into some type of new aircraft. I think the future has many new and amazing things to come beginning with vehicles.
    Tonya Sulham (3)

  2. To me, this is mind-blowing research! I would never have expected that the U.S. military are the biggest supporters of dragonfly research so they could possibly advance their own technology. Thank you for informing me of such riveting information. I had no idea that dragonflies are such efficient and accurate predators. Do you think they are the only insect with such impressive selective attention abilities?

    Lindsey Dugas (1)

  3. Does the neuron that preserves the response of the single stimulus pick the same stimulus out of the two every time?

    It seems like "locking on" to a random stimuli wouldn't be very adaptive. Obviously, since the dragonfly is such an efficient predator as you stated, there must be a neural mechanism for "choosing" which firing pattern is preserved, as well as one for switching which stimulus the neuron is displaying the firing pattern for.

    And how does the dragonfly deal with the "ignored" stimulus? It must still be aware that is there, but how does the decision that one stimulus is more important than the other get translated into the switch in firing pattern of this midbrain neuron to the pattern of that previously "ignored" stimulus. I guess answering some of these questions would lead to an even greater understanding of how we are able to focus our attention and how we decide where to direct it.

    Joseph Starrett(3)

    1. The paper that went over this research (which I linked in my post) couldn't find any mechanism by which the dragonfly's were choosing to discriminate one stimulus over the other. However, in their experiment they were just flashing dots on a screen at the insects, so the dragonflies didn't really have any vested interest in paying attention to one over the other. The main point was just demonstrating that they could switch their attention, something that is apparently not to common in insects. It would be interesting if they repeated this experiment, using a neutral dot as the initial stimulus, but using a fly or some kind of prey as the second stimulus. One would predict that the dragonfly would consistently flip it's attention from the dot to the prey, as opposed to randomly selecting between the two dots as in the original experiment. I'm sorry that I don't have better answers to your questions, but I think that would require more research to be done.

      Posted by Sean McDougall

  4. It is amazing that the military is actually studying this creature to mimic this fascinating ability. Does the military research any other creatures for similar purposes.

    posted by Ashley Sterpka (1)

    1. Yes, I actually looked up a project that started about three years ago called AIRFOILS (Animal Inspired Flight with Outer and Inner Loop Strategies). The Office of Naval Research awarded a five year 7.5 million dollar grant to researchers at Boston University, University of Maryland, and other institutions to research the flight mechanics of various bats, birds, and insects with the intent of translating their findings to the design of unmanned aircraft. I was completely unaware of the military's interest in studying the flight mechanics of various animals before reading this article as well. It seems like a great way to get this research done though, since the Department of Defense has no shortage of money to devout to R&D, and it is hard enough for researchers to get grant money from conventional sources such as the NSF.

      Posted By Sean McDougall

  5. What is the nature of the military's interest in dragonfly's tracking capabilities? I wonder what branch of the military is most interested and how would they translate what they learn into military use. Are dragonflies the only insects that can use this 'eye trick' to catch prey? I never thought of insects as having such sophisticated hunting behaviors.

    Kaitlin Jones (3)

  6. It would be difficult to get something to fly with the same agility as a dragonfly. It's evolved to fly that way, but the physics are amazing. It would be pretty incredible if they were able to match that same agile flying pattern on an aircraft.