Sea dragons are marine fish belonging to the Syngnathidae family. There are three species of sea dragon between two genera: The leafy sea dragon (Phycodurus eques), weedy/common sea dragon (Phyllopteryx taeniolatus), and ruby sea dragon (Phyllopteryx dewysea). Sea dragons have lobes of skin extending from their bodies, which can give them a dazzling, plant-like appearance. These appendages are actually camouflage that allow the animal to lurk among seaweed.
1. The “leaves” on sea dragons are actually lobes of skin so the animals can camouflage themselves among seaweed and kelp.
Leafy sea dragons have several greenish-yellow appendages that look like tiny leaves. These “leaves” are actually lobes of skin. They are perfectly shaped for the animal to blend in with surrounding seaweed. This adaptation protects the sea dragon from predators. It also hides the animal from prey. And because sea dragons are so lightweight, they gently tumble through the ocean with the same movements of seaweed.
Weedy sea dragons have a few small leaves, with dark red and yellow bodies. This makes them less plant-like than leafies.
Weedy sea dragons have a few small leaves as well. But they do not look identical to seaweed. Instead, they are red with yellow and purple spots. This species stands out more among seaweed and seagrass, but can blend in with coral reefs and sea rocks.
2. The sea dragon’s body is composed of small spines and bony plates under the skin for protection.
The sea dragon’s lobes of skin are for camouflage, but its body has some built in protection. Sea dragons have bony plates under their body’s skin for extra protection. These plates consist of several small spines running along their sides. Weedy sea dragons have yellow or purple stripes that accent these spines. On leafies, the spines look like thin white stripes along their yellowish-green bodies.
3. As members of the Syngnathidae family, sea dragons have long, narrow snouts that are actually their jaws
Sea dragons belong to the Syngnathidae family, along with seahorses and pipefish. Like their cousins, sea dragons have long, narrow snouts that they use to suck up prey. These snouts are actually the cheekbones that suspend the jaw. As Syngnathidae evolved, the cheekbones fused the jaws together, forming the snout. The family name is a combination of the Greek words for “together” and “jaw.”
Sea dragons prey on small crustaceans, mysid shrimp and other zooplankton, and fish larvae
Sea dragons are carnivorous, but don’t really have to hunt. They eat tiny crustaceans, zooplankton like mysid shrimp, and even larval fish. Leafy sea dragons blend in perfectly with seaweed. So they can suck up tiny prey floating near them with the ocean currents. Since sea dragons don’t have teeth, they swallow their prey whole.
4. Leafies can stay in place for 68 hours at a time.
Sea dragons are not very active animals. In a seaweed bed, a leafy has both the protection and access to prey it needs to survive. So a leafy will stay put for several days. Scientists monitored one leafy, and found that it stayed in the same place for 68 hours straight. That’s three days without leaving its spot. Leafies sway with the current, the same way seaweed does. So these subtle movements in the same spot are important to their camouflage.
5. Sea dragons have small, almost invisible fins along their backs, heads, and necks to swim
Sea dragons have very small and thin fins along their backs, heads, and necks. These fins are so delicate that they are translucent. Each weedy sea dragon has dorsal fins to propel it, and pectoral fins on its neck to position its body. Each leafy sea dragon has fins on its head for turning or steering. It also has a small dorsal fin near its tail to propel itself. There is a popular misconception that the leaves on leafies are for swimming.
It takes a leafy one hour to travel 150 meters (490 feet).
Leafies propel themselves with their dorsal fin, and steer with the fins along their head. But they are very slow swimmers. Scientists tracked one leafy sea dragon, and they discovered that it only moved 150 meters in one hour. That’s less than 500 feet. Despite their slow speed, leafies can travel hundreds of meters from their habitat and back.
6. To breed, female sea dragons deposit up to 250 eggs onto a special patch on the underside of the male’s tail.
Like seahorses, male sea dragons are responsible for child rearing. During mating, the female sea dragon will deposit up to 250 eggs onto a special patch on the underside of the male’s tail. The eggs are fertilized during the transfer. The male is then responsible for the eggs until they hatch. This usually takes between 4-6 weeks, but can take up to 9.
Only 5% of eggs actually survive to hatch
One female can deposit 250 eggs on one male. But most of those eggs will not hatch. Only 5% of the female’s eggs will actually hatch into newborns. It’s very common for one of the partners to drop eggs during mating. Sometimes, they will drop entire batches. Hatching can take 24-48 hours. The male will even rub his tale against a rock to aid in hatching. But this can also destroy eggs.
7. Newborn sea dragons are completely independent once they hatch.
The male sea dragon does not take care of the newborns. Once the eggs hatch, the newborns must take care of themselves. Sea dragons are born with external yolk sacs. They will eat their yolk sacs for the first few days of their lives. After that, they feed on zooplankton. As they rapidly grow, juveniles start hunting mysid shrimp.
8. In 2015, scientists discovered a third species of sea dragon, the ruby sea dragon (Phyllopteryx dewysea).
In 2015, a graduate student and a marine biologist at the Scripps Institute of Oceanography discovered a third species of sea dragon. They named it Phyllopteryx dewysea, with the common name ruby seadragon. The two were analyzing tissue samples from a specimen that was collected in 2007. Using advanced software for analyzing DNA, they discovered that this specimen was actually its own species.
The ruby sea dragon lives in deeper waters than the other species. It’s red color is better camouflage for the darker habitat
The common name ruby sea dragon was inspired by the animal’s dark red color. The deep red color doesn’t seem like it would be good camouflage among seaweed. But the ruby sea dragon lives in deeper water than the other two species. Red hues are better absorbed in the darker water. So the ruby red color is perfect to protect the sea dragon.
Could there be more sea dragons we don’t know about?
The ruby sea dragon was the first sea dragon species to be discovered in 150 years. So far, humans have now discovered only three species (the blue sea dragon is actually a nudibranch). There are 46 species of seahorse, and over 200 species of pipefish. Do you think scientists will discover more sea dragons? Out of the three we know about, which one is your favorite?
How endangered is this animal?
- IUCN status: Least concern.
There is not enough data to determine the status of the ruby seadragon.
- In western Australia, pollution and fertilizer runoff threaten sea dragons. Their habitats are very close to the coast, making them very vulnerable to human activity.
- Climate change and ocean acidification pose serious threats to coral reefs and seaweed beds where sea dragons live.
Sea dragons are only found along Australia’s southern coast, and nowhere else in the world.
- Collectors steal sea dragons from their habitats in order to sell them as pets or for ingredients in alternative medicine.
Many aquarists want to keep them because of their ornate bodies and small size. But they are difficult to take care of and do not survive long in home aquariums.
Also Known As
Leafy Sea Dragon, Common seadragon, Ruby seadragon, Weedy Seadragon
20–24 cm (8–9.5 in)
Tropical coastal waters
Southern and western coasts of Australia
Plankton, Shrimp, Small fish
2 - 10 years