The Weedy Sea Dragon (or Common Sea Dragon) is a very strange creature. Along with its cousin, the Leafy Sea Dragon, it is closely related to Seahorses, but larger and even stranger-looking.
These creatures look similar to Seahorses, but unlike them they do not swim upright but rather with their bodies fully extended and horizontal. Like Seahorses, they have a kind of toothless "trunk". Their head and neck are distinct from the main body. They have small leaf-like appendages along the body and tail and on the head, which they use to propel themselves with. This gives them an appearance similar to floating seaweed, hence the name.
The odd thing about looking at such a creature is that it looks like a plant in a way I'm now going to (try to) explain:
One of the basic differences between how plants look and how animals look is that with an animal, the basic plan is always the same. The number of limbs on a dog is not arbitrary, unlike as with a tree where the number of branches can vary wildly.* Yet with these Sea Dragons that is not the case. Though the number of "leaves" on the Weedy Sea Dragon's head, neck and body is always the same, that is not the case with the tail. Also, the size and shape of the appendages varies greatly.
Weedy Sea Dragons come in various shades of red, blue and yellow.
These fish are native to the seas of southern Australia, from about the Sydney area to south western Australia and to southern Tasmania. They live in coral reefs, rocky ledges, jetties, and sea grass forests, at dephts of ten to thirty meters. (Another source claims it's one to fifty meters.)
Since they have no teeth, they nourish themselves exlusively from small shrimp-like creatures (zooplankton) which they suck up through their trunks.
Like Seahorses, the Sea Dragons have a very curious mode of reproduction in that the males carry the eggs around with them. But unlike Seahorses those creatures do not have a pouch in which the eggs are deposited but rather carry them around externally, below the tail. Their skin forms a cup on each egg to keep it from falling off.
After an incubation time of about eight weeks, up to 250 young hatch during about a week's time. Since the young are released over a period of a few days, they are widely distributed and thus have a better chance of survival than if they hatched all at the same time and place.
Threats and Protection
The Weedy Sea Dragon is rather common and does not currently seem to be threatened, though of course that may change. Its natural enemies are Sea Anemones and fish. Unnatural threats: being caught in trawl nets and captured for aquariua, where they usually die. (Caring for these delicate creatures is very difficult - as far as I know, Sea Dragons live in captivity only in three aquaria in the whole world.)
* (Excepting Sea Anemones, Hydrae and similar animals, which aren't really individual creatures but rather colony organisms and thus can take on varying shapes.)
Note: There is some duplicate information in the Leafy Sea Dragon node. This was unavoidable since the two species are quite similar.