The Tamborine Mountain Escarpment Protection Precinct is rich with abundant insect life. One of the heroes of the Escarpment is the dragonfly, an amazing flyer, successful hunter and a most intelligent insect.
Dragonflies are ancient animals, having been around long before the evolution of the dinosaurs. In fact, some 250 million years ago, a species of dragonfly measured a wingspan 70cm across.
There are 6,000 species of dragonflies and damselflies in the world, with Australia housing some 320 known species.
Dragonflies – very agile flyers
Dragonflies are agile flyers, with some flying across oceans to get to their destination. They can fly up, down, forwards, backwards, left and right. They have four different flying styles; counter-stroking, phased-stroking, synchronised-stroking and gliding, and use these different styles for different reasons, such as needing to change direction very quickly (for this, they use synchronised-stroking).
Where do they live?
They start their lives as nymphs, which is the larval stage of the insect. They may spend several years as a nymph; while the adult may live for a few days or weeks only.
Dragonflies are most often seen around water, but not always, and are found on every continent except Antarctica.
Some dragonflies live in and near running water and some in still water. But, if partial to still water, they don’t cross over into running water and visa versa.
Threats to dragonfly species
Because many species of dragonfly rely on precise water temperatures, good oxygen levels and unpolluted water to survive, they can act as good bio-indicators to water quality. Some dragonflies in NSW are endangered, because their habitats have been negatively impacted on by human activity.
Loss of habitat – chiefly wetlands – threatens dragonfly populations worldwide.
For example, in Japan, the loss of 60 per cent of the country’s wetlands has forced dragonflies out of their natural habitat and into domestic ponds and local creeks.
In Africa, their numbers have dropped dramatically, making them a focus of conservation attempts on the continent.
A beneficial predator against disease
A study reported by United Press International argues small insects, such as the dragonfly, are “essential for a healthy ecosystem”. And they can contribute to protecting humans from infectious diseases, such as lime disease and malaria.
The report suggests that the 20th Century reduction in biodiversity might be linked to a global increase in infectious diseases in humans.
The study undertook a range of research methods, such as field surveys, lab experiments and mathematical modelling to find out if the presence of dragonflies (and other predator insects) reduces infections in frogs caused by trematodes (parasitic flatworms).
It found that where more flatworm predators existed, fewer frog infections caused by the flatworm were found.
United Press International: Small predator diversity key to a healthy ecosystem
According to a report cited in the New Scientist, dragonflies have between 11 and 30 different visual opsins (light-sensitive proteins in the eyes of animals).
This means dragonflies can see beyond our red, blue, green colour combination and may have vision that sets a precedent for the entire animal kingdom.
Add this to other studies, which have found dragonflies see ultraviolet as well as red, blue, green and they can recognise polarised light reflections off water and you have yourself an insect with amazing visual capacity.
New Scientist article: Dragonfly eyes see the world in ultra-multicolor
The celebrated dragonfly
Many cultures revere the dragonfly. Native American tribe, the Navajos, use them as a symbol for water purity. And in Japan they’re seen as symbols of courage, strength and happiness.
While not celebrated in Europe, they play a big part in folklore, where the dragonfly is seen as sinister. UK-ites have referred to them as the “Devil’s darning needle” and in Portugal they’ve been referred to as the “eye-snatcher”.
Dragonflies in poetry
Dragonflies have found themselves in poetry.
One of Alfred Lord Tennyson’s earlier poems celebrated the dragonfly …
Today I saw the dragon-fly
Come from the wells where he did lie.
An inner impulse rent the veil
Of his old husk: from head to tail
Came out clear plates of sapphire mail.
He dried his wings: like gauze they grew;
Thro’ crofts and pastures wet with dew
A living flash of light he flew.
There are many great online and print resources on dragonflies. Find out more about the dragonfly, an amazing animal.
They rely heavily on the protection of their habitat, chiefly, water quality for their survival. Any change to their environment can impact on the very water they need to survive.
PNAS article on dragonfly sight: Extraordinary diversity of visual opsin genes in dragonflies
PNAS article on predator diversity: Predator diversity, intraguild predation, and indirect effects drive parasite transmission
Find a dragonfly: Australian Dragonfly Identification Key
Australian Museum: Dragonflies and damselflies: Order Odonata