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Revision as of 15:45, 27 November 2012

Leafy seadragon
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Actinopterygii
Order:
Syngnathiformes
Family:
Syngnathidae
Subfamily:
Syngnathinae
Genus:
Phycodurus

Species:
P. eques
Binomial name
Phycodurus eques
(Günther, 1865)

The leafy seadragon or Glauert's seadragon,[1] Phycodurus eques, is a marine fish in the family Syngnathidae, which also includes the seahorses. It is the only member of the genus Phycodurus. It is found along the southern and western coasts of Australia. The name is derived from the appearance, with long leaf-like protrusions coming from all over the body. These protrusions are not used for propulsion; they serve only as camouflage. The leafy seadragon propels itself by means of a pectoral fin on the ridge of its neck and a dorsal fin on its back closer to the tail end. These small fins are almost completely transparent and difficult to see as they undulate minutely to move the creature sedately through the water, completing the illusion of floating seaweed.

Popularly known as "leafies",[2][3] they are the marine emblem of the state of South Australia and a focus for local marine conservation.

Description

Much like the seahorse, the leafy seadragon's name is derived from its resemblance to another creature (in this case, the mythical dragon). While not large, they are slightly larger than most seahorses, growing to about 20–24 cm (8–10 in). They feed on plankton and small crustaceans.

The lobes of skin that grow on the leafy seadragon provide camouflage, giving it the appearance of seaweed. 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 creature feeds by sucking up small crustaceans, such as amphipods and mysid shrimp, plankton and larval fish through its long, pipe-like snout.[2]

The leafy seadragon is related to the pipefish and belongs to the family Syngnathidae, 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 the weedy seadragon, which is multi-coloured and grows weed-like fins but is smaller than the leafy seadragon. Another unique feature are small,circular gill openings covering tufted gills, very unlike the crescent shaped gill openings and ridged gills of most fish species (Lourie 1999)Current research at the Scripps Institution of Oceanography is investigating the evolutionary relationships of the Syngnathidae[4] and the DNA variation of the two seadragon species across their ranges.[5]

Reproduction

As with seahorses, the male leafy seadragon cares for the eggs. The female produces up to 250 bright pink eggs, then deposits them on to the male's tail via a long tube. The eggs then attach themselves to a brood patch, which supplies them with oxygen. It takes a total of nine weeks for the eggs to begin to hatch, depending on water conditions. The eggs turn a ripe purple or orange over this period, after which the male pumps its tail until the infants emerge, a process which takes place over 24–48 hours. The male aids in the babies hatching by shaking his tail, and rubbing it against seaweed and rocks. Once born, the infant seadragon is completely independent, eating small zooplankton until large enough to hunt mysids. Only about 5% of the eggs survive. Leafy seadragons take about 28 months to reach sexual maturity.[6]

Movement

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 metres (490 feet) per hour.[7]

Threats

Leafy seadragons are subject to many threats, both natural and man-made. They are caught by collectors, and used in alternative medicine. They are vulnerable when first born, and are slow swimmers, reducing their chance of escaping from a predator. Seadragons are often washed ashore after storms, as unlike their relative the seahorse, seadragons cannot curl their tail and hold onto seagrass to stay safe.[8]

They have become endangered through pollution and industrial runoff as well as collection by fascinated divers who are entranced by their unique appearance. In response to these dangers they have been officially protected by the Federal Government of Australia.

Habitat

The leafy seadragon is found only in southern Australian waters, from Kangaroo Island at the eastern end of its range, westward to Jurien Bay,[9] 220 km (140 mi) north of Perth. It was once thought that individuals had very restricted ranges; however, further research has discovered that seadragons will 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 metres (164 feet) deep, around kelp-covered rocks and clumps of sea grass.[2] They are commonly sighted by scuba divers near Adelaide, especially at Rapid Bay and Edithburgh.[10]

In captivity

Due to being protected by law, obtaining seadragons is often an expensive and difficult process as they must be from captive bred stock, and exporters must prove their broodstock 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 federal fisheries 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 in captivity have so far been unsuccessful.[11]

Australia

Australian aquaria featuring leafy seadragons include the Sydney Aquarium,[12] the Melbourne Aquarium, and the Aquarium of Western Australia.[13]

United States

A number of aquaria in the United States have leafy seadragon research programs or displays. Among them are the Aquarium of the Pacific at Long Beach,[14] the Birch Aquarium at Scripps, San Diego,[15] and the Monterey Bay Aquarium;[16] in California; the Dallas World Aquarium, Texas;[17] the New England Aquarium, Boston;[18] the Point Defiance Zoo & Aquarium in Tacoma WA;[19] the Shedd Aquarium, Chicago;[20] and the Tennessee Aquarium.[21]

Cultural references

The leafy seadragon is the official marine emblem of the state of South Australia.[22] It also features in the logo of the Marine Life Society of South Australia Inc.[23]

A biennial Leafy Sea Dragon Festival is held by the District Council of Yankalilla, South Australia. It is a festival of the environment, arts and culture of the southern Fleurieu Peninsula, with the theme of celebrating the leafy seadragon. The inaugural festival in 2005 attracted over 7,000 participants and visitors.[24]

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, the Department of Environment and Heritage and the Marine Discovery Centre.[25][26][27] Made through a collaboration of The People's Republic of Animation, Waterline Productions and the SA Film Corporation,[28] the film is an introductory guide to marine conservation and the marine bioregions of South Australia suitable for 8-12 year olds,[29] 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.[30][31]

See also

References

  1. ^ a b IUCN Red List of Threatened Species > Phycodurus eques Accessed 6 April 2012.
  2. ^ a b c Yankalilla Visitor Information Centre > The Leafy Sea Dragon Retrieved 17 August 2011.
  3. ^ National Geographic > Animals > Leafy and Weedy Sea Dragon Retrieved 9 December 2011.
  4. ^ Wilson, N. G. & Rouse, G. W. (2010): Convergent camouflage and the non-monophyly of ‘seadragons’ (Syngnathidae: Teleostei): suggestions for a revised taxonomy of syngnathids. Zoologica Scripta, 39, 551–558. Accessed 9 December 2011.
  5. ^ Scripps > Marine Invertebrates Phylogenetics Lab > Seadragon Phylogeography Accessed 9 December 2011.
  6. ^ "Life History of the Weedy Sea Dragon". Research. Sydney Institute of Marine Sciencefishy facts. 9 September 2008. Retrieved 13 October 2008.
  7. ^ "Patterns of movement and habitat use by leafy seadragons tracked ultrasonically". Journal of Fish Biology (61). Oxford: Blackwell: 684–695. 2002. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  8. ^ Zoo and Aquarium Association Inc Retrieved 8 August 2008.
  9. ^ Morrison, Sue (1999). Wonders of Western Waters. Como, Western Australia: Department of Conservation and Land Management. p. 112. ISBN 0-7309-6894-4. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  10. ^ Underwater Photography Guide Website
  11. ^ Paula Branshaw-Carlson (2011): Seadragon husbandry in the new millennium: Lessons learned from the past will create a sustainable future. The Husbandry, Management and Conservation of Syngnathids 5th International Zoo and Aquarium Symposium, Chicago, 1–4 November 2011. Accessed 6 April 2012.
  12. ^ Sydney Aquarium > Southern Oceans > Leafy Sea Dragon Accessed 6 April 2012.<
  13. ^ Aquarium of Western Australia Retrieved 8 August 2011.
  14. ^ Aquarium of the Pacific > Online Learning Center > Leafy Seadragon Accessed 6 April 2012.
  15. ^ Birch Aquarium > There's something about seahorses Accessed 6 April 2012.
  16. ^ Monterey Bay Aquarium > Leafy sea dragon Retrieved 6 September 2011.
  17. ^ Dallas World Aquarium > Exhibits > Southern Australia Accessed 6 April 2012.
  18. ^ New England Aquarium > Animals and Exhibits > Leafy Seadragon Accessed 6 April 2012.
  19. ^ Point Defiance Zoo & Aquarium > Aquariums Accessed 6 April 2012.
  20. ^ Shedd Aquarium Rides Herd On Seahorse Conservation Accessed 6 April 2012.
  21. ^ Tennessee Aquarium > Leafy Seadragon Accessed 6 April 2012.
  22. ^ Leafy Seadragon Government of South Australia - Insignia and Emblems. Retrieved 19 July 2011.
  23. ^ Marine Life Society of South Australia Retrieved 8 August 2011.
  24. ^ "Leafy Sea Dragon Festival". Community events. District council of Yankalilla. 29 September 2008. Retrieved 13 October 2008.
  25. ^ Marine Discovery Centre > Newsletter 3-06 Retrieved 17 August 2011.
  26. ^ Department of Premier and Cabinet > Press release 13/6/2006: State's Marine emblem stars in new film Retrieved 17 August 2011.
  27. ^ National Library of Australia > Trove > The amazing adventures of Gavin a leafy seadragon Retrieved 17 August 2011.
  28. ^ SA Film Corporation > The amazing adventures of Gavin, a Leafy Seadragon Retrieved 17 August 2011.
  29. ^ Reef Watch > Newsletter 9.2 - June 2006 Retrieved 17 August 2011.
  30. ^ Marine Discovery Centre > Newsletter 3-08 Retrieved 17 August 2011.
  31. ^ Department of Premier and Cabinet > Press release 24/8/2008: Gavin goes to school Retrieved 17 August 2011.
  • Template:IUCN2006 Database entry includes a range map and a lengthy justification of why this species is near threatened.

External links

Wikimedia Commons has media related to Phycodurus eques.

Australia

International

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