Dragonflies

Order Odonata

Introduction

The dragonfly belongs to the Order Odonata. Odonata means "tooth-jawed" and comes from a classification system developed by the 18th century entomologist , Johann Christian Fabricius.

Dragonfly Characteristics

Dragonflies are predators and use their enormous eyes for hunting. They can search for prey in all directions (360 degrees) at the same time with their large compound eyes. Each eye contains up to 30,000 lenses.Their legs end in a clawed, three segment tarsi (feet), used for grabbing and holding prey, before it kills and then eats them. They also have biting mouth parts with toothed mandibles (jaws). The name dragonfly came from their fierce jaws (looks like a dragon's) which they use to catch flies.
The dragonfly has four wings and each wing is capable of independant motion giving it the ability to change direction instantaneously, even reverse. The adult dragonfly can reach speeds of 40km/h. The male dragonflies are colourful and very territorial and tend to live near water which they guard possessively. If another male dragonfly enters his territory a mid-air fight is likely to ensue. An adult dragonfly will bite if handled by a human and can give a painful pinch (so be careful).

Dragonfly Lifecycle

The dragonfly goes through three development stages in its life, egg, larva and adult. The female dragonfly will lay her eggs in fresh water , sometimes hiding her eggs in the safety of plant tissue or mud. The reason for this watery home is that when the eggs hatch the larvae (nymphs) will be aquatic. The egg cycle lasts between 6 - 30 days. The nymphs which emege from the eggs will be fully aquatic, using their gills (concealed in its rectum) for breathing. The rectum is also used for movement, the nymph moves along by pumping water in and out of its rectum. The nymph also has deadly jaws that shoot out a long lower lip (labium) to catch its prey. Prey consists of aquatic animals such as fish, tadpoles and water insects. Unfortunately for the poor old nymph, it will have to endure up to 15 development stages during its larval period. In that time the larva will develop its wings. Once the wings have developed to their final stage, the larva will emerge from the water and find a reed, plant or rock to complete its final stage of metamorphisis. Once the larva is safely perched out of the water it begins to shed its skin. For about an hour the adult will slowly wiggle out of its old skin to emerge and fly off as an adult dragonfly. Some species may take as long as three years to become an adult. 
The adult dragonflies live for only a relatively short time (up to three months) however in that time, the female can lay up to 3,000 eggs.