The Leafy Sea Dragon, scientifically known as ‘Phycodurus eques‘, is a fascinating marine creature found only in the coastal waters around the south and south west of Australia. It has one of the most unusual yet charming appearances in the marine world. Their appearance is no accident though and serves a very specific and important function. This solitary and elegantly camouflaged fish is not only the sole member of its genus, ‘Phycodurus‘, but doesn’t have any recognized subspecies either.
Within their lonely genus, they belong to the family ‘Syngnathidae‘ which also includes the genus ‘Phyllopteryx‘. It is in this genus that you find possibly its closing relatives in terms of appearance, the two species of Weedy Seadragon and the Ruby Seadragon. While similar, there are notable differences between these species. All seahorses and pipefish belong to this family, and are a part of the order ‘Syngnathiformes‘.
Appearance & Characteristics of the Leafy Sea Dragon
The leafy sea dragon, if lucky enough to reach maturity, can reach a size of between 20-24 cm (8-9.5 inches). They can be notoriously difficult to care for in captivity, and while alluring to the eye of many private collectors, this is usually to the animals detriment.
They move by drifting through the water, in a very slow, swaying motion. Its body adorned with long, leaf-like limbs which fluttering along with the ocean current, giving the ability to seamlessly blending into its seaweed and kelp surroundings. Despite their somewhat rigid outer skin, these creatures navigate their aquatic world with petite, nearly transparent fins, maintaining an illusion of floating seaweed.
Their name is very fitting, as they have the appearance of both seaweed, but also of the mythical dragon, particularly of Eastern Asian lore.
Differences Between The Leafy Seadragon and the Weedy Seadragon
| Leafy Seadragon | Weedy Seadragon | |
| Appearance | Leafy Sea Dragons have numerous leaf-like appendages, giving them a very ornate appearance. | Weedy Sea Dragons have fewer leaf-like appendages, with a more streamlined and less ornate appearance |
| Colour | Yellowish-brown to green coloration which helps them blend into their kelp and seaweed surroundings | Often have a reddish color with yellow spots, and they may also exhibit purple stripes |
| Size | Tend to be larger, often reaching up to 35 cm in length. | Typically smaller, with a maximum length of about 45 cm |
| Habitat | Found in the waters along the southern and western coasts of Australia | Found along the southeastern coast of Australia up to the coast of New South Wales |
| Camouflage | Leafy Sea Dragons use their leaf-like appendages for camouflage among significant seaweed growth | Weedy Sea Dragons, while still using camouflage, are often found in areas with less dense seaweed |
| Distribution | Leafy Sea Dragons have a more restricted distribution | Weedy Sea Dragons have a broader distribution |
| Scientific Classification | Leafy Sea Dragons belong to the genus Phycodurus | Weedy Sea Dragons belong to the genus Phyllopteryx |
Distribution – Location and Habitat
Exclusively found in the southern Australian coastal waters, the Leafy Sea Dragon’s range stretches from Wilson’s Promontory in Victoria, up past Perth to Jurien Bay in Western Australia. They often linger over areas where they can hide if needs be. Such as sandy patches, around kelp-covered rocks, or amongst clumps of sea grass. They don’t usually venture any deeper than waters up to 50 m (160 ft) deep.
This environment provides a perfect backdrop for their seaweed mimicry. They are believed to have good sense of direction and location, often travelling several hundred miles only to return to the same spot later. While having a relatively limited range in the wild, they are also kept in captivity in several aquariums around South East Asia, North America and in major Australian cities.
The Lifestyle & Behaviour of the Leafy Sea Dragon
Leafy Sea Dragons are very cautious animals, and are a predominantly solitary animal. Communication and social interactions among them remain largely a mystery to biologists. They are very slow, drifting or floating along powered by their small, nearly invisible pectoral and dorsal fins. As one of the slowest animals around, they have evolved to use camouflage and stealth rather than speed as their main method of predatory evasion.
They only usually come together when it’s mating season, and they don’t really group together for any other purpose at all. Their solitary existence is an advantage in their attempts to avoid being spotted in their environment. If they hung out in groups, they would be much easier to spot without the ability to run away from any threats.
Camouflage and Mimicry – Mastering Their Seaweed Surroundings
There are many animals that camouflage, but none other than perhaps stick insects, are quite as unique and specialised as the Leafy Sea Dragon.
While they don’t have the power to outrun any predators, they have evolved with remarkable leaf-like appendages and complement this with the ability to change colour. Though their colour changing abelites change according to their diet, age, location, and stress level. Together with their purposeful yet slow, swaying motion, these talents give them the perfect stealth to blend into their seaweed and kelp filled environments.
This provides them not only the best chance of confusing and outsmarting any threats, but also an advantageous ambush strategy for catching their own prey.
Diet & Nutrition of the Leafy Sea Dragon
The leafy sea dragon has a rather specific carnivorous diet, which is mostly made up of small crustaceans, amphipods and tiny shrimp, plankton and larval fish that they can easily find sharing their habitat. These are all prey that don’t require much effort or movement to capture. To eat their prey, they they skilfully suck their meal up through their elongated, pipe-like snouts. This diet as well as being easy to catch, also gives them the opportunity to remain well concealed without having to chase their prey down.
Predators & Threats to the Leafy Sea Dragon
The camouflage and mimicry of the adult Leafy Sea Dragon is so effective, that they have no specific natural predators in their environment. They share environment with many large carnivorous fish, but by taking on the appearance of kelp, with their camouflage intact these large fish are not interested. When the camouflage of an adult fails them however, it doesn’t take much effort for a predator to lock them down. While not common, they may still end up on the menu for some sharks and possibly the eastern blue groper fish.
Young Leafy Sea Dragons are not quite as lucky and do have a few predators that are only too happy to make a meal of them. When they are born, these fish tend to hatch together. This makes them easy to spot and a target for many fish, but also sea anemones and larger crustaceans. Not many juveniles make it to adulthood because they are an easy meal for predators.
Their biggest threat however, is likely to be from human activities such as pollution and industrial runoff. They are very sensitive to environmental changes, and anything that can impact the stability of the kelp and seaweed growth in their habitat has direct impact on these fish too. Human activity and also climate change can effect them in this way.
Then there is the aquarium trade. Despite their conservation status and efforts, they are still often caught for collectors, and in some cases killed for use in alternative ‘medicine’. They don’t breed well in captivity so disrupting natural populations can have a very detrimental impact on the population.
Leafy Sea Dragon Reproduction
In what is quite rare amongst fish and in the animal kingdom in general, it is the male that takes on the duty of carrying the eggs once successful fertilisation has taken place. When in season, the female deposits up to 250 bright pink eggs onto the male’s tail, where they attach to a specialized brood patch that supplies them with oxygen. While the male takes on the caregiver role, both breeding partners will stay together usually until the young have emerged from their eggs. The female may leave sooner.
After approximately 9 weeks, the young emerge, fully independent and capable of hunting small zooplankton. The time it takes them to emerge may vary by location, or by year depending on environmental conditions, particularly water temperature. In warmer water they may emerge much sooner, and in colder water their development can be delayed.
They don’t receive any further parental care once they have emerged. This is the most vulnerable stage of life for these little fish. They all emerge at the same time and this makes them easy to spot. They don’t start to develop their limbs and appendages to take on their camouflaged form for a few days after birth, and they don’t yet have the experience to master the skill. While all close together and not yet able to master their skills, they are an easy target.
Lifespan of Leafy Sea Dragon
The Leafy Sea Dragon, once it has navigated the vulnerable period of youth, can expect to live a relatively modest life of between three to ten years. They can reach a similar lifespan in captivity, and the average is around 6 years for those that are lucky enough to reach maturity. However, for the majority, they don’t get this far. In fact, only around 5% of eggs survive to have a chance at life, and of that 5%, many don’t make it past the first few weeks due to predation.
Population and Conservation
As of the latest assessment in 2016, the Leafy Seadragon is Listed as ‘Least Concern’ by the IUCN, on the Red List of Endangered Species. It is nonetheless subject to various threats that have prompted various protective measures in several Australian states.
Conservation efforts and legal protections aim to safeguard these enchanting creatures from the risk of endangerment. As they are listed on the conservation act in Australia, any development plans that could have an impact on the species, have to take their welfare into consideration by law. They are extremely sensitive to environmental changes, and the balance of their population levels can be extremely vulnerable to even small changes.
5 Fun Leafy Sea Dragon Facts for Kids
- Leafy Sea Dragons can change colour to blend into their surroundings!
- Male Leafy Sea Dragons carry and hatch the eggs!
- They are slow swimmers, using tiny, transparent fins to glide gracefully through the water.
- Leafy Sea Dragons usually live a solitary lifestyle, quietly exploring their underwater world.
- The Leafy Sea Dragon is the marine emblem of the state of South Australia!
