Leafy seagdragon the protected marine emblem of South Australia; state has two species of seahorses

The leafy seadragon, a totally protected species in South Australia, with (inset) its relative, the seahorse, whose two main species in South Australia, the snout-nosed and potbelly, are both also protected.

Leafy seadragons, a unique species of marine fish with leafy appendages enabling them to camouflage themselves in weedy habitats, became South Australia's state marine emblem.

Found only in southern Australian waters, “leafies” were commonly sighted by scuba divers near capital city Adelaide, especially at Rapid Bay, Edithburgh and Victor Harbor. Because of natural and man-made threats, the species was totally protected in South Australia in 1987. 

The leafy seadragon (phycodurus eques) or Glauert's seadragonis was classified as a fish in the syngnathidae family, including sea horses and pipefish. The leafy seadragon propelled itself with pectoral and dorsal fins that are transparent and moved the creature sedately, completing the illusion of floating seaweed. The leafy seadragon changed colour to blend in but this depended on diet, age, location and stress level. Another unique feature is the small circular gill openings covering tufted gills.

Research showed seadragons travelled several hundred metres from their habitual locations, returning to the same spot using a strong sense of direction. They were mostly found over sand patches in waters up to 50 metres deep, around kelp-covered rocks and clumps of sea grass.  Leafy seadragons usually lived solitary lifestyle, pairing up only to breed, when the males cared for the up to 250 bright pink eggs. From hatching, leafy seadragons were completely independent. By the age of two, they were typically full grown and ready to breed. The species fed by sucking up small crustaceans through its long pipe-like snout.

The man-made threats to leafy seadragons include being caught by collectors and use in alternative medicine – in addition to pollution and industrial runoff. They are vulnerable to predators as slow swimmers when first born. Seadragons are often washed ashore after storms – unlike their seahorse syngnathidae relatives that could curl their tails and hold onto seagrasses to stay safe.  

The short-snouted and potbelly were South Australia’s two seahorse species out of 50 in the world. The short-snouted, only 10 centimetres tall, was found around Venus Bay and Denial Bay on the Eyre Peninsula. They clung  to drifting or anchored seaweed.

The potbelly was one of the largest seahorses, growing to 35cm tall. It hooked its tail around a sea sponge or seaweed. It ate shrimp or crustacean.  Potbellies could be brown, purple, orange or yellow with distinctive black spots. Potbelly seahorses were only found in the Southern Ocean, from the Great Australian Bight through to Tasmania and New Zealand.

The common seahorse, bigbelly and dull seahorse also have been seen in South Australian waters. All are protected from fishing or being collected.