, the weedy seadragon
or common seadragon
, is a marine
Marine biology is the scientific study of organisms in the ocean or other marine or brackish bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather...
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
related to the seahorse
Seahorses compose the fish genus Hippocampus within the family Syngnathidae, in order Syngnathiformes. Syngnathidae also includes the pipefishes. "Hippocampus" comes from the Ancient Greek hippos meaning "horse" and kampos meaning “sea monster”.There are nearly 50 species of seahorse...
. It is the only member of the genus Phyllopteryx
. Adult weedy seadragons are a reddish colour, with yellow and purple markings; they have small leaf-like appendages that provide camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...
and a number of short spines for protection. Males have narrower bodies and are darker than females. Seadragons have a long dorsal fin along the back and small pectoral fins on either side of the neck, which provide balance. Weedy seadragons can reach 45 cm in length.
The weedy seadragon is the marine emblem of the Australian State of Victoria
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
It is found around the southern coastline of Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, approximately between Port Stephens, New South Wales and Geraldton, Western Australia
Geraldton is a city and port in Western Australia located north of Perth in the Mid West region. Geraldton has an estimated population at June 2010 of 36,958...
, as well as around Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
The weedy seadragon inhabits coastal waters down to at least 50 metres deep. It is associated with rocky reefs, seaweed beds, seagrass meadows and structures colonised by seaweed.
These fish are slow-moving and rely on their camouflage as protection against predation; they drift in the water and with the leaf-like appendages resemble the swaying seaweed of their habitat. They lack a prehensile tail that enables similar species to clasp and anchor themselves.
Individuals are observed either on their own or in pairs; feeding on tiny crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and other zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
by sucking prey into their toothless mouths. Like seahorses, seadragon males are the sex that cares for the developing eggs. Females lay around 120 eggs onto the brood patch located on the underside of the males tail. The eggs are fertilised and carried by the male for around a month before the hatchlings emerge. Seadragons, seahorses and pipefish
Pipefishes or pipe-fishes are a subfamily of small fishes, which, together with the seahorses, form the family Syngnathidae.-Anatomy:...
are the only known species where the male carries the eggs. The young are independent at birth, beginning to eat shortly after.
Mating in captivity is rare since researchers have yet to understand what biological or environmental factors trigger them to reproduce. In captivity the survival rate for weedy seadragons is about 60%.
The Aquarium of the Pacific
in Long Beach, California and the Tennessee Aquarium
The Tennessee Aquarium is a non-profit public aquarium located in Chattanooga, Tennessee. Its River Journey building is the largest freshwater aquarium in the world....
in Chattanooga, Tennessee in the USA; and the Melbourne Aquarium
Melbourne Aquarium is a Southern Ocean and Antarctic aquarium in central Melbourne, Australia. It is located on the banks of the Yarra River beside and under the Flinders Street Viaduct and the King Street Bridge.-History:...
in Melbourne, Australia are the only facilities in the world to have successfully bred weedy seadragons in captivity, though others occasionally report egg laying. As of June 2008, the Georgia Aquarium
The Georgia Aquarium, located in Atlanta, Georgia, United States, at Pemberton Place, is the world's largest aquarium with more than of marine and fresh water housing more than 120,000 animals of 500 different species...
in Atlanta, USA had a pregnant seadragon, which was expected to give birth in early-mid July.
The weedy sea dragon is classified as Near Threatened (NT) on the IUCN Red List 2006. This species is not at present a target of the trade in Traditional Chinese Medicine, which is currently affecting seahorse numbers. However, they are likely to be threatened by the destruction of habitat that is occurring along coastal waters as a result of development and pollution.
Currently, it is illegal to take or export these species in most of the states within which they occur. 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. 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.
A more cryptic relative of the weedy seadragon is the leafy seadragon, Phycodurus eques
. In the November 2006 issue of National Geographic
National Geographic, formerly the National Geographic Magazine, is the official journal of the National Geographic Society. It published its first issue in 1888, just nine months after the Society itself was founded...
magazine, marine biologist Greg Rouse is reported as investigating the DNA variation of the two seadragon species across their ranges.