Sea Dragons

Sea Dragons

      Two species of sea dragons occur in southern Australia, the "common" or Weedy Sea Dragon (Phyllopteryx taeniolatus)and the Leafy Sea Dragon (Phycodurus eques). Both species resemble floating pieces of seaweed which can make them difficult to find in their natural habitat which has a plethora of kelp like macroalgae. Jim is an expert at finding sea dragons and is probably one of the worlds experts on their habits and environment. He keeps a log of their movements and growth annotating individuals by snout markings on the right side.

Weedy Sea Dragons

     

The Weedy Sea dragon is endemic to (i.e. they are found only in) southern Australian waters. Adult Weedy Sea dragons grow to about 46 centimeters in length. The small, leaf-like appendages of Weedy Sea Dragons come out from the body singularly or in pairs. While colors vary on live animals, adult Weedy Sea dragons are usually reddish with yellow spots and purple-blue bars. The "leaves" are often purple in color with a black border. The body has only a few short spines. The species of sea dragon are known to inhabit rocky reefs, seaweed beds, seagrass meadows and around any structures colonized by seaweed. While they have been found in depths of up to 50 meters, they are more often seen in shallow coastal waters. Sea dragons feed on plankton, larval fishes and small shrimp-like crustaceans, called mysids, sucking up their prey in their small mouths. Like the seahorses to which they are closely related, males of this species bear the unhatched eggs. Unlike seahorses, however, the eggs are not enclosed in a pouch but are clutched externally along the tail where the skin forms a cup around each egg. Reaching maturity after one year, weedy sea dragons typically breed during their second year, and may grow to a length of 17 inches. Like the Leafy sea dragon, their diet includes mysid shrimp.

Leafy Sea Dragons

      Anyone who has seen a leafy sea-dragon cannot fail to make the connection between this tiny gossamer-like creature and the dragons of fairy tales. This rare and vulnerable relative of the sea-horse might be only around 45 centimeters long and live in an element foreign to its fierce mythical cousin, but in appearance it is unmistakably a dragon.

      Sea-dragons actually belong to the same family as sea-horses (Syngnathidae) but differ in appearance from the latter by possessing leaf-like appendages on their head and body, and having a tail that cannot be coiled up.  Unique to the southern waters of Western Australia and South Australia, the leafy sea-dragon's home is inshore areas of sea grass. Unfortunately these are under increasing threat from pollution and excessive fertilizer run-off. 
This is not the only danger faced by the sea-dragon. Although having no known predators amongst the marine world, it has become the target of unscrupulous 'collectors' who have denuded the more accessible seagrass areas of this amazing creature.

      In 1991, the WA Fisheries Western Australia, concerned by the rapidly decreasing numbers of the leafy sea-dragon, declared it a totally protected species. The sea-dragon is poorly equipped for fleeing from those who wish to catch it. The outer skin or 'hide' of the sea-dragon is solid, limiting its mobility, and the only way it can propel itself along is through rapidly oscillating its ventral and dorsal fins. However, it blends easily with the background and is agile enough to be able to hunt down tiny mysid shrimp or 'sea-lice', its main quarry. For those creatures, the sea-dragon has all the appearance of a mighty hunter.

      Perhaps the most extraordinary thing about the leafy sea-dragon is that it is actually the male of the species which gets pregnant and gives birth. During mating, the female lays 100 - 250 eggs onto a special 'brood patch' on the underside of the male's tail, where they are attached and fertilized. This brood patch, consisting of cups of blood-rich tissue each holding one egg, is especially developed by the male for use during the breeding season of August to the following March. The bright pink eggs become embedded in the cups of the brood patch, receiving oxygen via the cups' blood vessels. During each breeding season, male leafy sea-dragons will hatch two batches of eggs. After a period of about four to six weeks from conception, the male 'gives birth' to miniature juvenile versions of sea-dragons. As soon as a baby sea-dragon leaves the safety of its father's tail, it is independent and receives no further help from its parents. For two to three days after birth, the baby sea-dragons are sustained by their yolk sac. After this, they hunt small zooplankton, such as copepods and rotifers, until large enough to hunt juvenile mysids.

      The leafy sea-dragon is one of two species of sea-dragon found in Australia's southern waters. The common or weedy sea-dragon (Phyllopteryx taeniolatus) is less rare and can be encountered all the way from Port Stephens, New South Wales to Geraldton, Western Australia.

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