The term 'sea dragon' may create a fearsome image in your mind. In reality, sea dragons are marine fish that belong to the family Syngnathidae, which includes sea horses and pipefish. The characteristic features of this family are the long snouts, fused jaws, absence of pelvic fins, and the role of males in fertilization and incubation. In short, this family includes some amazing marine fish which look different from the conventional ones. Sea dragons belong to the genus Phycodurus and Phyllopteryx. Both genera have only one species each, called the leafy sea dragon (Phycodurus eques) and the weedy sea dragon (Phyllopteryx taeniolatus) respectively.
So, sea dragons are not fearsome marine animals, but are small marine fish. There are two types of sea dragons - leafy and weedy sea dragons. The leafy sea dragon is one of the most amazing, beautiful, and delicate marine fish, due to its leafy appendages. Sea dragons are closely related to seahorses, but both are entirely different, and belong to different subfamily and genera.
Why the Name Leafy Sea Dragon?
As the name rightly suggests, this sea dragon has leafy appendages. They look like sea horses, but differ from the latter in various aspects. The most common differences include the presence of leafy appendages on their body, absence of the coiled tail, and absence of a belly pouch for rearing the young.
The leafy appendages are so ornate and delicate, that the fish looks beautiful and fragile. However, they have an armor of scales, that cover and protect the body. The leafy appendages are actually meant for the purpose of camouflaging, as it is very difficult to differentiate this fish from the floating seaweed. These leafy appendages are generally green to yellowish brown in color. They change color according to the surroundings. The color changing nature of this fish may vary with factors, like age, diet, stress levels, and location.
The leafy appendages have no role in their movements, which are accomplished with the help of a pectoral fin on the ridge of its neck, and a dorsal fin, which is located on the back of the tail. These fins are also very small and transparent. The leafy sea dragon has two eyes above its snout, and these eyes have the ability to move independently. In short, this fish can look at many directions, at the same time. This amazing creature has no teeth, but a long snout, which helps them to suck in small fish, shrimp, mysids, and plankton. The camouflaging ability helps them to catch their prey, which is sucked in through the straw-like snout.
Habitat and Habits
Leafy sea dragons are usually found in the Australian waters. They travel to far regions and return to the original spot. Their habitat includes rocky reefs, seaweed beds, sea grass meadows, and sand patches near coral reefs covered with sea weeds. They are slow-moving animals, and while moving, they look like drifting sea weed only. This makes this fish, the only animal in the world, which hides by moving. Even though, they have the ability to camouflage, they are also equipped with long, sharp spines on their body to defend themselves.
The male members are responsible for caring of the eggs, and carrying the young ones. It has been observed that, in males, the color of the tail turns deep yellow, during the mating period. A female can produce up to 250 pink-colored eggs, which are then deposited on the male's tail, through a tube-like appendage. These eggs get attached to the brood patch on the tail of the male. The brood patch provides the eggs with oxygen and fertilizes them. The eggs will hatch after nine weeks, but the time taken for hatching may vary with the water conditions. During this nine-week period, the color of the eggs changes from pink to purple or orange. The hatching process is aided by the males, who pump their tails till the young ones emerge from the eggs. Only a small percent (around 5%) of the eggs survive to form young sea dragons, which become completely independent, soon after birth. They reach sexual maturity within 28 months.
Apart from predators, leafy sea dragons are threatened by both human activities and natural disasters. While they are washed ashore during strong storms, humans catch them for preparing alternative medicine. They are also kept in aquariums. However, these marine fish cannot survive outside their natural habitat. Now they are listed as 'near threatened', and are protected by law in Australia.