Leafy seadragons (Phycodurus eques) are exquisitely camouflaged fish. Belonging to the same family as seahorses and pipefish (Syngnathidae), they resemble these with their elongated snout and bony-plated body (2). Leafy seadragons are yellowish-brown to green in colour, although they may vary depending on their age, diet or location (2). The pectoral fins are located on the neck, and a dorsal fin runs along the seadragon's back (3). As their common name suggests, there are a number of leaf-like appendages along the body, which help to make these fish resemble the seaweed of their habitat. The eyes are located above the elongated snout and there are a number of defensive spines along the sides of the body (2).
Leafy seadragons are seen either solitarily or in pairs, they are slow-moving and rely on their elegant camouflage to provide protection from predators (2). In common with seahorses, it is the male seadragon that carries the developing eggs. The breeding season runs from October to March (5), and males develop a 'brood patch' on the underside of the tail that consists of cups of blood-rich tissue, which each hold an egg (4). The female transfers around 120 eggs into these pits; the eggs are then fertilised and carried by the male for about a month (2). Hatchlings emerge over several days and are initially only around 20 millimetres in length. They are extremely vulnerable to predation but grow quickly, attaining adult size by the time they are two years old (2). Seadragons feed on small organisms such as plankton and mysids by sucking them into their tube-like snout (2).
Unlike seahorses, seadragons are not in demand from the Traditional Chinese Medicine market but they may nevertheless be captured for the aquarium trade. Loss of habitat is considered the greatest threat to seadragons. Coastal habitats are increasingly damaged from the effects of urban and agricultural run-off, industrial pollution and other human activities and impacts (5).
Little is known about the population distribution of leafy seadragons, or much of their behaviour. They are fully protected in Australian waters (4). A database of seadragon sightings, known as 'Dragon Search' has been established with support from the Marine and Coastal Community Network (MCCN), Threatened Species Network (TSN) and the Australian Marine Conservation Society (AMCS), which encourages divers to report sightings (2). Monitoring of populations may provide indications of local water quality and seadragons could also become an important 'flagship' species for the often-overlooked richness of the unique flora and fauna of Australia's south coast (2).
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