Dragonflies are members of the order Odonata (meaning "toothed one" in Greek), they are ancient and successful insects. One species of dragonfly that existed 300 million years ago is the largest insect recorded: its wingspan was 70 cm. There are approximately 6,000 species of dragonflies worldwide, and 320 in Australia.

Their appearance is characterised by small antennae, large mandibles, enormous eyes plus three small ocelli, tilted thorax, long slender abdomen and two pairs of veined membranous wings of similar shape and size. They have excellent sight, their compound eyes may have up to 30,000 individual lenses, and their head can rotate almost 360 degrees.

Many species have brightly coloured bodies and wings. Modern dragonflies are smaller than their ancestors, the largest species have wingspans of 19 cm and a body length of 12 cm and the smallest species has a wingspan of 1.7 cm.

There are three stages in the dragonfly’s life cycle. Adult dragonflies mate in the air and the female lays eggs on a water plant or in the water. The egg hatches into a nymph (larva). The nymph is a flattened chunky creature with wing pads and six legs located near its head. The nymph breathes by drawing water over its internal gills, so it is well adapted to life underwater. Growth and development occur and the nymph has multiple moults before it climbs out of the water for a final nymphal moult and emerges as a fully developed adult. Dragonflies spend most of their life as nymphs; most species spend an average of 1-2 years as nymphs and only a few weeks to a year as adults.

Dragonflies are found in a wide range of freshwater environments and are sensitive to pollution and habitat disturbance.

Both nymphs and adults are highly effective hunters which use sophisticated locomotion. Nymphs have a hollow bladder, which is lined with tracheal gills; water is drawn in across the gills then expelled as a powerful column of water that jet propels the nymph through the water. The adult dragonfly is unable to walk but is a prodigious acrobatic flier due to independent control of each of its four wings. Maneuverability with acceleration recorded as 4g in straight lines and 9g in turns, the ability to move in any direction, hover, as well as achieve speeds of sixty km per hour plus endurance are achieved by complex aerodynamic processes.