| Leafy seadragon | |
|---|---|
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| OffKangaroo Island,Australia | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Syngnathiformes |
| Family: | Syngnathidae |
| Subfamily: | Syngnathinae |
| Genus: | Phycodurus T. N. Gill, 1896 |
| Species: | P. eques |
| Binomial name | |
| Phycodurus eques (Günther, 1865) | |
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| Phycodurus eques range | |
| Synonyms | |
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Theleafy seadragon (Phycodurus eques) orGlauert's seadragon, is a marinefish. It is theonly member of the genusPhycodurus in the familySyngnathidae, which includesseadragons,pipefish, andseahorses.[2]
It is found along the southern and western coasts ofAustralia. The name is derived from their appearance, with long leaf-like protrusions coming from all over the body. These protrusions are not used for propulsion; they serve only ascamouflage. The leafy seadragon propels itself utilising a pair ofpectoral fins on the sides of its neck and adorsal fin on its back closer to the tail end. These small fins are almost completely transparent and difficult to see as theyundulate minutely to move the creature sedately through the water, completing the illusion of floatingseaweed.
Popularly known as "leafies", they are themarine emblem of the state ofSouth Australia and a focus for local marine conservation.[3][4]
The generic name is derived from the Greek wordsφῦκοςphûkos "seaweed"[5] andδέρμαderma "skin".[6][7]
Much like theseahorse, the leafy seadragon's name is derived from its resemblance to another creature (in this case, the mythicaldragon). While not large, they are slightly larger than most seahorses, growing to about 20–24 cm (8–9.5 in). They feed onplankton and smallcrustaceans.
The lobes of skin that grow on the leafy seadragon providecamouflage, giving it the appearance of seaweed.[8] It is able to maintain the illusion when swimming, appearing to move through the water like a piece of floating seaweed. It can also change colour to blend in, but this ability depends on the seadragon's diet, age, location, and stress level.
The leafy seadragon is related to thepipefish and belongs to the familySyngnathidae, along with the seahorse. It differs from the seahorse in appearance, form of locomotion, and its inability to coil or grasp things with its tail. A related species is theweedy seadragon, which is multicoloured and grows weed-like fins, but is smaller than the leafy seadragon. Another unique feature is the small, circular gill openings covering tufted gills, very unlike the crescent-shaped gill openings and ridged gills of most fish species.[9]
The leafy seadragon is found only in southern Australian waters, fromWilson’s Promontory inVictoria at the eastern end of its range, westward toJurien Bay, 220 km (140 mi) north ofPerth inWestern Australia.[1][10] Individuals were once thought to have very restricted ranges; but further research has discovered that seadragons actually travel several hundred metres from their habitual locations, returning to the same spot using a strong sense of direction. They are mostly found over sand patches in waters up to 50 m (160 ft) deep, around kelp-covered rocks and clumps of sea grass.[3] They are commonly sighted by scuba divers nearAdelaide in South Australia, especially atRapid Bay,Edithburgh, andVictor Harbor.[11][12]
Leafy seadragons usually live a solitary lifestyle. When the time comes, males court the females, they then pair up to breed. From the moment they hatch, leafy seadragons are completely independent. By the age of two, they are typically full grown and ready to breed.[13]
The species feeds by sucking up small crustaceans, such asamphipods andmysid shrimp,plankton, andlarval fish through its long, pipe-like snout.[3]
As with seahorses, the male leafy seadragon cares for theeggs. The female produces up to 250 bright pink eggs, then deposits them onto the male's tail with herovipositor, a long tube. The eggs then attach themselves to a brood patch, which supplies them with oxygen. After 9 weeks, the eggs begin to hatch, depending on water conditions. The eggs turn a ripe purple or orange over this period, after which the male pumps his tail until the young emerge, a process which takes place over 24–48 hours. The male aids the hatching of the eggs by shaking his tail, and rubbing it against seaweed and rocks. Once born, the young seadragon is completely independent, eating smallzooplankton until large enough to huntmysids. Only about 5% of the eggs survive.[3] Each newborn fry begins life with a small, externally-attached yolk-sac. This sac provides them sustenance for their first few days of life. Despite this initial nutrition source, the majority of fry will instinctively learn to hunt and catch prey upon hatching, and will become self-reliant before the sac is gone.[14]
The leafy seadragon uses the fins along the side of its head to allow it to steer and turn. However, its outer skin is fairly rigid, limiting mobility. Individual leafy seadragons have been observed remaining in one location for extended periods of time (up to 68 hours), but will sometimes move for lengthy periods. The tracking of one individual indicated it moved at up to 150 m (490 ft) per hour.[15]
Leafy seadragons are subject to many threats, both natural and man-made. They are caught by collectors, and used inalternative medicine.[citation needed] They are vulnerable when first born, and are slow swimmers, reducing their chance of escaping from a predator. Seadragons are sometimes washed ashore after storms.[16]
The species has become endangered throughpollution and industrial runoff, as well as collection for the aquarium trade. In response to these dangers, the species has been totally protected inSouth Australia since 1987,Victoria since at least 1995, andWestern Australia since 1991. Additionally, the species' listing in theAustralian government'sEnvironment Protection and Biodiversity Conservation Act 1999 means that the welfare of the species has to be considered as a part of any developmental project.[1][17][18]
Due to being protected by law, obtaining seadragons is often an expensive and difficult process as they must be fromcaptive bred stock, and exporters must prove theirbroodstock were caught before collecting restrictions went into effect, or that they had a license to collect seadragons. Seadragons have a specific level of protection under federalfisheries legislation as well as in most Australian states where they occur.[1] Seadragons are difficult to maintain in aquaria. Success in keeping them has been largely confined to the public aquarium sector, due to funding and knowledge that would not be available to the average enthusiast. Attempts to breed the leafy seadragon incaptivity have so far been unsuccessful.[19]
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Australian aquaria featuring leafy seadragons include theSydney Aquarium,[20] theMelbourne Aquarium, and theAquarium of Western Australia.[21]
Ripley's Aquarium of Canada inToronto displays both leafy and weedy seadragons.[22][23]
S.E.A. Aquarium, located in theMarine Life Park ofSingapore, displays both leafy and weedy seadragons.
A number of aquaria in the United States have leafy seadragon research programs and/or displays. Among these are theAdventure Aquarium in Camden, New Jersey;[24]Aquarium of the Pacific at Long Beach;[25]Birch Aquarium in San Diego;[26] theMinnesota Zoo;[27]Monterey Bay Aquarium;[28] theDallas World Aquarium & theDallas Children's Aquarium, Dallas;[29] theNew England Aquarium, Boston;[30] thePoint Defiance Zoo & Aquarium in Tacoma, Washington;[31] theNewport Aquarium in Kentucky,[citation needed] theShedd Aquarium, Chicago;[32] theCalifornia Academy of Sciences;[33] theTennessee Aquarium;[34]Sea World Orlando, Florida; thePittsburgh Zoo & PPG Aquarium;,[35] Ripley's Aquarium of the Smokies, Gatlinburg, Tennessee;[citation needed], The Florida Aquarium[36] in Tampa, Florida; the Mote Aquarium in Sarasota, Florida;[citation needed], and Ripley's Aquarium Broadway at Myrtle Beach, South Carolina.[citation needed]
The Lisbon Aquarium (Lisboa Oceanarium) has both leafy sea dragons and weedy sea dragons.[37]
The leafy seadragon is the official marine emblem of the state of South Australia.[38] It also features in the logos of the following South Australian associations — theAdelaide University Scuba Club Inc. and theMarine Life Society of South Australia Inc.[39][40]
A biennialLeafy Sea Dragon Festival is held within the boundaries of theDistrict Council of Yankalilla in South Australia. It is a festival of the environment, arts and culture of theFleurieu Peninsula, with the theme of celebrating the leafy seadragon. The inaugural festival in 2005 attracted over 7,000 participants including 4000 visitors.[41]
In 2006, an animated short film,The Amazing Adventures of Gavin, a Leafy Seadragon, was made on behalf of several South Australian organisations involved in conserving the marine environment, including the Coast Protection Board, theDepartment of Environment and Heritage and the Marine Discovery Centre.[42][43][44] Made through a collaboration ofThe People's Republic of Animation, Waterline Productions and theSA Film Corporation,[45] the film is an introductory guide to marine conservation and the marinebioregions of South Australia suitable for 8–12 year olds,[46] and copies were distributed on DVD to all primary schools in the State. An educator's resource kit to accompany the film was released in 2008.[47][48]
Australia
International
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