Classification:

Phylum Chordata
Class Osteichthyes
Order Gasterosteiformes
Family Sygnathidae
Subfamily Solegnathinae

Related animals:

Seahorses and pipefish

Visual description:

Deepwater individuals are usually more dark brown to burgundy, while
those that live in shallow water are more yellow to greenish. The sea
dragon's snout is generally longer than seahorses' snouts. Leafy sea
dragons have ornamental appendages that give the appearance of attached
leaves. These appendages act as a camouflage so that the animal seems to
blend into or look like a plant. It has a large bony protrusion above
its eye. Unlike the seahorse, the male sea dragon does not have a pouch
to hold its eggs; instead, it broods them in a patch of spongy tissue
along its tail. Like the seahorse, the sea dragon's body is coved with
bony plates. The sea dragons have several long, sharp spines along the
side of their bodies.

Size:

Sea dragons grow to about 14 inches (35cm).

Lifespan:

Aquarium-raised animals adapt to captivity and artificial light and can
live more than 10 years. No statistics exist for those that live in
nature.

Range:

The south coasts of the states of South Australia and Western Australia,
rarely found north of Perth or in waters of southern Victoria.

Habitat:

Usually the sea dragon lives above 27 feet (25m) deep. Fresh water
run-off and rough conditions regulate those that surface. Southern
Australian waters are temperate.

Behavior:

Typical of this family of fish, the sea dragon is a very slow swimmer
and must depend upon its ability to blend in with and mimic plants for
camouflage. Sea dragons have been observed "curled up" so that they can
present their spines as a protection against attacking fish.

Diet:

Mysids and shrimp are the usual food, and larger adults may eat reef
crustaceans. 

Reproduction:

Generally they live and mate in deeper water, but some may congregate in
shallow bays, where they eventually mate. In the first few months after
hatching, they grow rapidly and reach half their adult size. The growth
rate slows, but weight increases so that the young adults are ready to
breed at one year. It takes almost two years to reach full size. The
spawning ritual begins in October, at which time the male's tail becomes
swollen and yellow. The female deposits her eggs in a way similar to the
pipefish and the seahorse. Each egg needs to be pushed through the skin
to become fertile, and they are deposited not in a pouch but on the
tail. 

When the eggs become fertile, the soft skin hardens to hold the
eggs. Incubation takes about 8 weeks. Males brood 250-300 eggs, cover
most of the underside and sides of the tail immediately behind the anus.
Within a short time the eggs can be covered with algae. They are partly
embedded in the skin and are about 3/16 inch (4mm) in diameter and 5/16
inch (7mm) long. After mating, pregnant males move to deeper water
during November and December. The hatchlings are about 1-3/8 inch (35mm) long. They unroll from the tight egg capsule tail first. The process
takes from 3 to 6 hours until the newly hatched sea dragon is ready to
swim. Its yolk sack supports it for two days. 

The newly hatched are well advanced. Hatching of all eggs may take 6 to 7 days, and the father will distribute them over a wide area. The young may swim in loose congregations to shallower, sheltered water about 16-23 feet (5-7 m) deep, where they live among the shallow sand, weeds and rubble. 

Predators and endangerment:

Fish and other larger aquatic animals eat sea dragons. The limited
research suggests that sea dragons may be a "flagship species" for
conservation and are sensitive to water quality changes.  

Notes:
Most states in Australia protect the sea dragons. Wild adults have a
hard time surviving transport, are sensitive to light changes, and are
difficult to adapt to captivity. Most captive sea dragons have been
aquarium raised. 

Sources:
Australian Museum. "Fish in Focus".
Kuiter, pg. 80-87.
Lourie, et.al., pg. 153.

© 2002  text by Guy Di Torrice