Leafy Seadragon Profile
The waters around Australia are home to some of the most unique and stunning fauna on the planet.
The Great Barrier Reef in the North, the world’s largest reef system, is a bustling metropolis for biodiversity that includes 400 types of coral, 1,500 species of fish and 4,000 types of molluscs, to name a few.
But on the temperate Southern side of the island is a unique, partially enclosed marine system where you’ll find 80% of the breeding sea lion populations, 32 species of cetaceans, and over 70 native bird species. Beneath the surface, among the hundreds of fish species, there are the sea dragons.
These colourful, yet intricately camouflaged little dudes are so hard to see that almost nothing eats them. And you can tell, by the way the leafy sea dragon carries itself, they certainly know this.
Leafy Seadragon Facts Overview
| Habitat: | Shallow marine, temperate |
| Location: | South coast of Australia |
| Lifespan: | 3 years in captivity |
| Size: | Up to 50 cm (20 in) long |
| Weight: | Unknown |
| Colour: | Yellow-brown or greenish with dark pink rib bands |
| Diet: | Small crustaceans, fish |
| Predators: | Few as adults, anemones, crustaceans, fish as young. |
| Top Speed: | Slow, occasionally up to 17 metres per hour |
| No. of Species: | 1 |
| Conservation Status: | Least Concern (IUCN) |
Leafy seadragons are a species in the pipefish family, similar to the seahorses. As such, they share similarities such as an unusual reproductive strategy that results in a pickier male than we’re normally used to.
These tiny, ornate fish are formidable predators, despite being blindingly slow, and are important contributors to the seagrass, kelp and shallow marine ecosystems.
Being so pretty, they’re popular in aquaculture, and this has led to their nomination as a flagship species to represent and protect a vulnerable and unique habitat found nowhere else on Earth.
Interesting Leafy Seadragon Facts
1. They’re in the seahorse family
Pipefish, seahorses and seadragons make up the family Syngnathidae, which are a group of bony fishes named for their fused jaws, which form a sort of bony snout that protrudes from their faces, sometimes taking up half of the total length of the animal.
This family of fishes is known for its unique feeding mechanism, in which energy is stored in the muscles used to rotate the head, and released rapidly for a lightning-fast acceleration of their mouths towards their food.
They’re also characterised by the way they split the parenting chores. 1
2. Males look after the eggs
In animals for whom the female is the one to incubate and birth the young, females need to be selective in their partner choice.
This is a product of the imbalance of reproductive resources required between the sexes. A single male can breed with multiple females in quick succession so he doesn’t need to be all that fussy about their genetic fitness.
But the female needs to make hers count, which is why you often see multiple males in the animal kingdom engaging in complex courtship rituals to persuade the single female they’re worth breeding with, or single males defending multiple females from competitors.
But this ratio isn’t defined by sex, rather it’s defined by the roles each sex takes on. So, in leafy sea dragons – a species in which the male takes on the role of nurturing parent and all the female has to do is provide the gametes – you see those behaviours reversed.
Like in seashores, this species delegates the majority of the reproductive responsibilities to the male. And so, you find that males are more selective about who they’ll get it on with.
When a pairing has been agreed upon, a female will release around 420 eggs, 300 to 350 of which will be stuck onto the male’s brood pouch and carried around by him for about 9 weeks until they hatch.
The male will help them escape by shaking them off or rubbing them against some seaweed, but after that, they’re on their own. From birth, they are independent, and instantly set to work hunting for prey, carrying around a yolk sac that will help them through the first few days’ energy requirements while they learn.
Around 5% of these eggs will make it to adulthood, and they will take on larger prey as they age.
3. They’re predators
It’s hard to imagine an animal as ornate and lethargic as a seadragon wanting to kill and eat another animal, but these little flowery creatures are important predators of smaller animals.
Most of their prey are shrimp, but they will also predate other small crustaceans and fish larvae, using their special hunting method and a form of suction that pulls their unfortunate victim into the elongated mouth. 2
4. They’re slow
One of the things that makes the food choices of this fish a bit surprising is just how sluggish they are. Seadragons tend to stay in roughly the same place all their lives, moving very little between a handful of spots within their ranges.
And when they do move, it’s hardly at breakneck speeds. One research paper mentioned “bursts” of speed, on occasion reaching the face-melting velocity of 0.01 mph.
Without a tail fin, they’re slow and weak swimmers and can go several days without moving at all. This means they have to rely on other means to avoid being eaten.
5. They’re camouflaged
The leafy part of this sea dragon’s name comes from the frond-like appendages it’s absolutely covered with. They have a distinctly kelp-like appearance, with the same sort of textures and colours you’d expect from a large piece of algae.
To make matters worse, this species will also rock back and forth, resembling the movement of the water on things that aren’t fish. This camouflage is so effective, that neither predators nor prey can usually find a seadragon, and if they do, it has another trick up its sleeve.
6. They’re also sharp
One other characteristic of this fish family is its bony plates, which enclose most of their bodies in an uncomfortable and protective layer of armour.
These fish don’t have scales, and each of the bony plates has long, sharp spines on them, which makes biting down on the animal a bad idea for most potential predators. 3
7. They need seagrass
This species is listed as of Least Concern by the IUCN but its habitat might not be as stable.
These fish are dependent on the seagrass beds and reefs around them and both of these are highly vulnerable to human interference. Stormwater discharge from urban centres has already begun to destroy these habitats, and seagrass is in decline from sedimentation from wastewater sent from the city.
Other concerns are the occurrences of bycatch from trawling and potentially the collection of individuals for the pet trade, but the effects of both of these factors are still poorly understood.
As of now, they are the official fish emblem of the state of South Australia, and so bring in a lot of tourism, which can be good and bad for the species. 4
8. They’re a flagship species
This increase in popularity can be used to the benefit of conservationists looking to protect a unique habitat, as the security of one popular species brings with it a cascade of benefits to those species around it and the ecosystem as a whole.
Conservation actions for the protection of the leafy seadragon include the widespread protection of the habitat as a whole, its connectivity to other habitats and the genetic health of the animals and plants that live around it.
Leafy Seadragon Fact-File Summary
Scientific Classification
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Syngnathiformes |
| Family: | Syngnathidae |
| Genus: | Phycodurus |
| Species: | eques |
Fact Sources & References
- Robert Kenneth Browne (2008), “Syngnathids: Seadragons, Seahorses, and Pipefishes of Gulf St Vincent”, Research Gate.
- “Leafy Seadragon”, IUCN Red List.
- “Leafy Seadragon”, Aquarium of the Pacific.
- “Leafy Seadragon”, IUCN Red List.