Gallery: Here Be Dragons
01Libellulidae
__Look at how happy this little fellow is! That's because it's about to kill and eat something.__ Dragonfly nymphs (immature stages) are aquatic predators. The "face" on this nymph is actually incredibly fast weaponized mouthparts. Photo © Jan Hamrsky.
JAN HAMRSKY02Libellulidae
In this photo, you can see how the mask covering the face is actually a shovel for stuffing prey into the nymph's mouth. Which makes it slightly less cute. The mask is made up the lower "lip", or Labium, of the dragonfly. At rest it is folded under the head and thorax between the legs. Photo © Jan Hamrsky.
Jan Hamrsky03Aeshnidae - labium
In this photo, the labium is extended. It's basically a pressurized hydraulic grabber. The nymph clenches its anus (more about this below) and contracts its thoracic and abdominal muscles to increase its body cavity pressure and push out the labium. The mask shoots out within milliseconds and harpoons prey with the two sharp "fangs" on the edge of the labium. The shape of the mask and the teeth on the edge are a key way to identify different species of dragonfly nymphs. Photo © Jan Hamrsky.
Jan Hamrsky04Aeshnidae
This side view shows how the labium folds back under the body, but also is used in handling prey items while they are consumed. Photo © Jan Hamrsky.
JAN HAMRSKY05Aeshnidae
Even vertebrates need to fear freshwater dragons, as this tadpole learned too late. Larger species of dragonfly nymphs will eat minnows and tadpoles, as well as any other dragonfly nymphs they can latch onto. Photo © Jan Hamrsky.
Jan Hamrsky06Spiketail dragonfly nymph (Cordulegastridae)
This Spiketail dragonfly nymph (Cordulegastridae) is an ambush predator. This series of photos shows how it buries itself to lie in wait for unsuspecting prey. You might notice it forgot to bury a part--its butt. That's because dragonflies breathe via anal gills. But wait! There's more! The gills have a secret function: Jet propulsion. Water in the rectal chamber can be jetted out at high pressure, pushing the nymph forward through the water. The forward thrust generated has been measured as 1.5 g in 0.1 second, and up to 10cm/second. Photo © Jan Hamrsky.
JAN HAMRSKY07Cordulegastridae
As dragonfly nymphs grow, their wings begin to develop. You can see the beginnings of 4 wings in this photo. Dragonflies have simple metamorphosis--they gradually change into their adult form. Dragonfly larvae molt varying numbers of times, and live from 1 to 6 years underwater before climbing onto land to assume their final form. Insects like moths and flies have complete metamorphosis; there are distinct changes in shape and form between larvae (caterpillars and maggots) and adults with a pupal stage. Photo © Jan Hamrsky.
JAN HAMRSKY08Dragonfly emerging
As the dragonfly nymph prepares to make its final transformation, it crawls up out of the water onto nearby vegetation. This photo shows a newly emerged adult next to its split open, shed nymphal outer skin (exoskeleton). As the dragonfly rests, it once again uses hydraulic body pressure, this time to expand its new soft outer shell and inflate the wings. You might notice two whitish strings extending out of the shed skin. Those are the remnants of the main tracheal trunks, a breathing system that runs through the entire insect. The inside of the respiratory system is also lined with exoskeleton, and is also shed when the insect molts. Once the dragonfly dries off and the exoskeleton hardens, it's ready to fly off and begin terrorizing animals in the air instead of water. It has assumed its final form. Photo © Jan Hamrsky.
