The Leafy Dragons of the Sea

Named after the dragons of Chinese legends, the leafy seadragons, Phycodurus eques, are bony marine fish of the family Syngnathidae, which includes pipefish and seahorses. Although relatives, their appearance is slightly different in that they have a tail that cannot coil and leaf-like appendages on their head and body. These protrusions are not used for propulsion rather camouflage. They are primarily known as “leafies” and native along the southern and western coasts of Australia and a real focus for local marine conservation.

Physical Characteristics

The scaleless body of seadragons is covered in hard bony plates. They have a small head with a long, thin pipe-like snout and a tail half the total length of their bodies. Intricate leaf-like appendages distend from from their heads, bodies and tail. The transparent dorsal and pectoral fins are small and have a dainty appearance but lack  caudal and pelvic fins. The sharp spines on their bony plates are used defensively.

Slow-swimming and with fragile bodies, the leafy seadragon’s appendages of skin develop to provide camouflage, disguising it with the appearance of seaweed. While swimming, it is able to maintain the illusion of a floating piece of seaweed. Their leafy appendages, maintaining the ability to change color to match their seaweed and seagrass habitats, sway like plants in the water current to protect themselves from predators.

Much like the seahorse, the leafy seadragon’s name is derivative of the resemblance to mythical dragons. While not very large, they are slightly bigger than most seahorses, growing approximately 35 cm, feeding on plankton and small crustaceans.

Habitat

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Leafy Seadragon Range

Seadragons inhabit the costal waters of southern
Australia where temperatures are seasonally 55-67 degrees Fahrenheit. Living among the rocky reefs, sandy patched, seaweed beds and seagrass meadows, populations fluctuate seasonally in response to food availability and spawning season.

Behavior

Leafy Seadragon Swimming

These usually solitary creatures move into deeper waters during Australian winters when food is scarce. Late winters consists of congregations to mate in selected shallow bays.

The outer skin of these fish is solid, limiting their mobility. Rapid oscillation of pelvic and ventral fins propel them through waters. The pelvic fins are used primarily for maneuvering. To hold their position vertically or move themselves up and down the water column the amount of air in the swim bladders fluctuate.

Reproduction

Like their seahorse relatives, males brood the eggs but incubated under the tail instead of the abdominal pouch. The females lay approximately 275 eggs, pushing them into the skin of the male to be fertilized mostly covering under the surface and sides of the tail directly under the anus. Upon egg insertion, the males skin is soft but becomes hardened to form a cup of secure protection for the 6-8 weeks of incubation. A male releases a few eggs at a time when they are ready to hatch, taking a couple hours to days releasing the entire brood.

The fry unravel from their tight position in the eggs capsule, exiting tail first. The are colored silver and black with leaf-like appendages and a small snout. Settling on the substrates in shallow waters, they live off the still-attached egg capsule until their snout is developed and ready to begin hunting.

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Diet

Lacking teeth and a stomach, seadragons are almost constantly eating, covering side areas lurking for prey. They feed on mysid shrimp and other small crustaceans, plankton and larval fish. They swallow their prey entirely, creating suction, practically inhaling their food item whole by expanding a joint on the lower part of their snout. Their feeding technique is similar to that of how a pipette works.

Conservation

Since 2006, the IUCN Red List pronounced leafy seadragrons as near endangered due to habitat destruction, pollution, excessive fertilizer runoff and poaching by humans. They are fully protected under Australia’s local, state and federal legislation. Special licenses were required to collect and export them. In 2015, such licenses were ceased by the Australian government. Because they are inhabitants of moderate waters, the increase of temperatures as a result of global climate change may have impacted their survival unless they are able to adapt.

Resources:

Pacific, Aquarium Of the. “Aquarium of the Pacific.” Aquarium of the Pacific | Online Learning Center | Leafy Seadragon. Aquarium of the Pacific, n.d. Web. 23 Nov. 2016.

Society, National Geographic. “Leafy and Weedy Sea Dragons, Leafy and Weedy Sea Dragon Pictures, Leafy and Weedy Sea Dragon Facts – National Geographic.” National Geographic. National Geographic Partners, n.d. Web. 23 Nov. 2016.

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