Sea Dragon Facts: Diet, Habitat, Reproduction

Sea dragons are real—they live in Australia

The leafy sea dragon blends in with its environment.
The leafy sea dragon blends in with its environment.

Lisa Spangenberger, Getty Images

The sea dragon, or seadragon, is a small fish found in shallow coastal waters of Tasmania and southern and western Australia. The animals resemble seahorses in terms of size and body shape, but feature small, leaf-like fins that camouflage them from predators. While seahorses can grip objects with their tails, sea dragon tails are not prehensile. Sea dragons awkwardly propel themselves with their transparent dorsal and pectoral fins, but mainly drift with current.

Fast Facts: Sea Dragon

  • Common Name: Sea dragon, seadragon (common/weedy, leafy, ruby)
  • Scientific Names: Phyllopteryx taeniolatus, Phycodurus eques, Phyllopteryx dewysea
  • Other Names: Glauert's seadragon, Lucas's seadragon
  • Distinguishing Features: Small fish that resembles a sea horse with small leaf-like fins
  • Average Size: 20 to 24 cm (10 to 12 in)
  • Diet: Carnivore
  • Lifespan: 2 to 10 years
  • Habitat: Southern and western coastal regions of Australia
  • Conservation Status: Least Concern
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Syngnathiformes
  • Family: Syngnathidae
  • Fun Fact: The leafy sea dragon is the marine emblem of South Australia, while the common sea dragon is the marine emblem of Victoria.

Types of Sea Dragons

There are two phyla and three species of sea dragons.

Phylum Phyllopteryx

  • Phyllopteryx taeniolatus (common sea dragon or weedy sea dragon): The common or weedy sea dragon occurs off the coast of Tasmania and in Australian waters ranging from the Eastern Indian Ocean to the South Western Pacific Ocean. These sea dragons have small leaf-like appendages on their fins and a few protective spines. The animals are reddish, with purple and red markings. Males are darker and narrower than females. Common sea dragons reach a length of 45 cm (18 in). They are found in reefs, seaweed, and seagrass.
  • Phyllopteryx dewysea (ruby sea dragon): The ruby sea dragon was discovered in 2015. This species inhabits the coast of Western Australia. The ruby sea dragon resembles the common sea dragon in most respects, but it is red-colored. Scientists believe the coloration may help the animal camouflage itself in the deeper waters it inhabits, in which red hues are more readily absorbed.
The common or weedy sea dragon features spines and fewer leafy appendages than the leafy sea dragon.
The common or weedy sea dragon features spines and fewer leafy appendages than the leafy sea dragon. Pere Soler, Getty Images

Phylum Phycodurus

  • Phycodurus eques (leafy sea dragon or Glauert's sea dragon): The leafy sea dragon has numerous leaf-like protrusions that camouflage it from predators. This species lives along the southern and western coasts of Australia. Leafy sea dragons change color to blend in with their environment. They grow to a length of 20 to 24 cm (8.0 to 9.5 in).
Leafy protrusions and the ability to change color make the leafy sea dragon nearly invisible against its surroundings.
Leafy protrusions and the ability to change color make the leafy sea dragon nearly invisible against its surroundings. Shin Okamoto, Getty Images

Diet

Sea dragon mouths lack teeth, yet these animals are carnivores. They use their snouts to suck up larval fish and small crustaceans, such as plankton, mysid shrimp, and amphipods. Presumably, numerous species would eat sea dragons, but their camouflage is sufficient to protect them from most attacks.

Reproduction

Except for mating, sea dragons are solitary animals. They reach sexual maturity by one to two years of age, at which time the males court females. A female produces up to 250 pink eggs. They are fertilized when she deposits them onto the male's tail. The eggs attach to a region called the brood patch, which supplies eggs with oxygen until they hatch. As with seahorses, the male cares for the eggs until they hatch, which takes about 9 weeks. The male shakes and pumps his tail to aid hatching. Sea dragons become completely independent as soon as they hatch.

Weedy sea dragon with eggs.
Weedy sea dragon with eggs. Brandi Mueller/Stocktrek Images, Getty Images

Conservation Status

Both weedy and leafy sea dragons are listed as "Least Concern" on the IUCN Red List of Threatened Species. There is insufficient data to evaluate the conservation status of the ruby sea dragon. Some sea dragons get washed up by storms. While fishing bycatch and aquarium collection do affect the species, these effects are not believed to greatly impact the species. The most significant threats are from pollution, habitat degradation, and habitat loss.

Captivity and Breeding Efforts

Like seahorses, sea dragons are difficult to keep in captivity. While it's not illegal to own one, Australia prohibits their capture, only granting permits for research and conservation efforts. You can view these fascinating animals at most large aquariums and zoos.

Researchers have successfully bred the common or weedy sea dragon. While Ocean Rider in Kona, Hawaii has gotten leafy sea dragons to mate and produce eggs, no leafy sea dragons have been born in captivity yet.

Sources

  • Branshaw-Carlson, Paula (2012). "Seadragon husbandry in the new millennium: Lessons learned from the past will create a sustainable future" (PDF). 2012 International Aquarium Congress 9–14 September 2012. Cape Town: 2012 International Aquarium Congress.
  • Connolly, R. M. (September 2002). "Patterns of movement and habitat use by leafy seadragons tracked ultrasonically". Journal of Fish Biology. 61 (3): 684–695. doi:10.1111/j.1095-8649.2002.tb00904.x
  • Martin-Smith, K. & Vincent, A. (2006): Exploitation and trade of Australian seahorses, pipehorses, sea dragons and pipefishes (Family Syngnathidae). Oryx, 40: 141-151.
  • Morrison, S. & Storrie, A. (1999). Wonders of Western Waters: The Marine Life of South-Western Australia. CALM. p. 68. ISBN 0-7309-6894-4.
  • Stiller, Josefin; Wilson, Nerida G.; Rouse, Greg W. (February 18, 2015). "A spectacular new species of seadragon (Syngnathidae)". Royal Society Open Science. The Royal Society. 2 (2): 140458. doi:10.1098/rsos.140458