The official marine emblem of the state of South Australia is a creature that you might associate with myth, but leafy seadragons really do exist. They are less fearsome than their name would suggest – beautiful in shape and colour, they seemingly drift through the ocean.
These bony fish are endemic to the coastal waters off south and east Australia and are hidden in plain sight – their camouflaging appendages give them a plant-like appearance. These unique and fascinating marine creatures suck up their food and, like seahorses, the males are responsible for childbearing.
Are leafy seadragons fish?
Leafy seadragons are fish.
What is so special about them?
They may be fish but leafy seadragons don’t have scales. Instead, their rigid bodies are covered with bony plates, with long spines along the sides of their bodies that may be used defensively. It has leaf-like appendages on its body, head and tail. Their heads are small with long, thin snouts, and their eyes can move independently of one another. Their fins are transparent and their tails, which cannot be coiled, are about half their length. Leafy seadragons are usually yellowish to greenish-brown in colour.
How do they camouflage themselves?
The leaf-like appendages on the head, body and tail not only give these fish their common name but also enable them to resemble floating seaweed and blend into their habitat, protecting them from predators. Leafy seadragons are also able to change colour to match their surroundings.
How big are leafy seadragons?
Leafy seadragons measure up to 35cm long and weigh between 3-6g.
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How do they move?
Their movements also mimic the swaying motion of seaweed. They rely on a pair of pectoral fins and one dorsal fin to steer and move slowly through the water (they have lost their caudal and pelvic fins) and use their swim bladders to control buoyancy.
How fast are leafy seadragons?
They can travel at approximately 0.15kph.
What do leafy seadragons eat?
The long, pipe-like snout and small mouth work like a pipette, allowing the fish to suck up mysid shrimps and sea lice. Other prey includes small crustaceans, plankton and larval fish. Leafy seadragons swallow their prey whole and do not have teeth or stomachs, so they eat continuously.
Where do they live?
They inhabit the coastal waters of Australia, where temperatures fluctuate between 13°C and 19°C. These fish live among seagrass meadows, seaweed beds, rocky reefs and sand patches near weed-covered reefs, from the surface to depths of 30m.
What is their lifespan?
Little is known about how long leafy seadragons can live in the wild but lifespan is estimated at between seven and 10 years.
Are leafy seadragons poisonous?
Leafy seadragons aren't poisonous.
Do male leafy seadragons give birth?
Male leafy seadragons become pregnant and give birth to live young.
How do leafy seadragons mate?
Unlike the pouch that seahorses have, a male leafy seadragon has a special brood patch on the underside of his tail, which develops as mating season (October to January) approaches. Here, the female deposits up to 250 eggs during mating. The eggs are fertilised during the transfer from the female to the male. The male incubates the eggs and keeps them secure, providing them with the necessary levels of oxygen. After about four to six weeks, miniature seadragons are gradually released into the water. During each breeding season, the male will usually hatch two batches of eggs.
What are baby leafy seadragons like?
Baby leafy seadragons emerge from their egg capsule tail-first. They have a short snout, lack leafy appendages, and are silver and black in colour. As soon as a hatchling leaves the safety of its father’s tail, it is independent. For the first two days, it lives off the still-attached egg capsule before it starts hunting.
How big are the young?
At birth, the young are about 2cm long, making them highly vulnerable to predators, with only one in 20 surviving to adulthood. However, they grow rapidly, reaching 20cm within a year and attaining their full length by the age of two.
How many species are there?
The leafy seadragon (Phycodurus eques) is one of three species of seadragon: the others are the weedy, or common, seadragon (Phyllopteryx taeniolatus) and the ruby seadragon (Phyllopteryx dewysea). Seadragons are relatives of seahorses and bony fish that belong to the family Sygnathidae (pipefish and relatives). All three species of seadragon are only found in Australian waters.
Do leafy seadragons face any threats?
They are illegally collected by people looking to keep them as pets. Pollution caused by excessive fertiliser run-off and ongoing coastal development, habitat loss and degradation, and being caught as bycatch has also caused their numbers to decline. Because they are inhabitants of temperate waters, seadragons may be impacted by an increase in water temperature due to climate change.
Are leafy seadragons extinct?
No, but according to the IUCN, the leafy seadragon and weedy seadragon populations are decreasing, and the ruby seadragon population is unknown (the species was only discovered in 2015). All three species are fully protected, along with all other sygnathids, by the Australian Environment Protection and Biodiversity Conservation Act 1999.
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Main image: leafy seadragon. Credit: Getty
