Aquatic Macroinvertebrates
Amazing transformations
Aquatic macroinvertebrates are small animals (without a backbone) that live all, or part, of their lives in water. The ones featured below have a larval or nyphal stage and spend their adult lives outside water.
Many are very sensitive to pollution- which gives us a good idea of how healthy a waterway is.
Pictured here is a dragonfly nymph using its extendable jaw to catch prey.
Small but essential
Some creeks in the Manly Dam environs have a great diversity of aquatic life, others (concerningly) are devoid of life.
These aquatic creatures break down living (and decaying) plant material into forms of energy that can be consumed by other animals.
They are an important part of the food chain-providing a source of nourishment for frogs, birds, reptiles and fish.
Image: A frog leaps for and misses a dragonfly meal.
Meet some of the aquatic macroinvertebrates of Manly Dam.
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![Dragonfly]()
Dragonfly
They are excellent hunters of other flying insects and can hover, move in zigzags, and even fly backwards. And they are fast - some of the larger dragonflies can reach flying speeds of 70 km per hour.
Fossils from larger Dragonfly-like insects have been found from 325 million years ago, long before the dinosaurs evolved. -
![Dragonfly nymph]()
Dragonfly nymph
Dragonfly nymphs feed off other smaller animals, including smaller invertebrates making them predators. They have striking mouth parts that can extend out to catch prey.
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![Blue Damselfly]()
Blue Damselfly
Adult damselflies catch and eat flies, mosquitos and other insects. They are similar to Dragonflies but are smaller and have slimmer bodies.
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![Damselfly Nymph]()
Damselfly Nymph
Damselfly larvae have gills at the base of their tail which enable the animal to breathe under water. Like dragonflies, damselflies are also predators and have specialised mouthparts that can extend to catch prey.
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![Caddisfly]()
Caddisfly
There are approx 14,500 described species.
Adults are short-lived, do not feed, or at most ingest fluids. -
![Caddisfly nymph]()
Caddisfly nymph
Caddisfly larvae are scraper feeders which scrape algae from the rocks they live on, or filter material from the water current. Some types are even predators of insects and crustaceans.
These water bugs are sensitive to pollution so their presence is used as an indicator of water quality. -
![Mayfly.]()
Mayfly
There are 3,000 species worldwide. Immediately following emergence from the nymph stage, the adults fly in an erratic up and down flight pattern over water or nearby rocks and bushes, mate in flight, lay eggs on the surface of a water body and die, usually within a day.
Mayflies are popular with fly fishermen as they are good fish food. -
![Mayfly nymph]()
Mayfly nymph
Mayfly nymphs are scraper feeders which scrape algae from rocks or eat decaying plant and animal material.They have feathery gills on their abdomen and 3 tails at the end of their abdomen.
These water bugs are sensitive to pollution so their presence is used as an indicator of water quality. -
![Alderfly]()
Alderfly
Alderflies are active at twilight or during the night, and are attracted to light.
Alderflies, in both the larva and adult stages, are important food for fish. -
![Alderfly nymph]()
Alderfly nymph
A fearsome predator, feeding on other bugs, they are nicknamed ‘toebiters’.
These water bugs are sensitive to water pollution so their presence is used as an indicator of water quality. Healthy streams have highly sensitive bugs.
