Saturday, January 5, 2013

Leafy Sea Dragon


About animals | Leafy Sea Dragon | Sea Dragons are arguably the most spectacular and mysterious of all ocean fish. Though close relatives of sea horses, sea dragons have larger bodies and leaf-like appendages which enable them to hide among floating seaweed or kelp beds. Sea dragons feed on larval fishes and amphipods, such as and small shrimp-like crustaceans called mysids ("sea lice"), sucking up their prey in their small mouths. Many of these amphipods feed on the red algae that thrives in the shade of the kelp forests where the sea dragons live.



As with their smaller common seahorse (and pipefish) cousins, the male sea dragon carries and incubates the eggs until they hatch. During mating the female deposits up to 250 eggs onto the "brood patch" on the underside of the male's tail. After about eight weeks, the brood hatches, but in nature only about 5 per cent of sea dragons survive to maturity (two years). A fully grown Leafy Sea Dragon grows to about 18 inches (45 cm).


Leafy Sea Dragons are very interesting to watch-- the leafy appendages are not used for movement. The body of a sea dragon scarcely appears to move at all. Steering and turning is through movement of tiny, translucent fins along the sides of the head (pectoral fins, visible above) and propulsion derives from the dorsal fins (along the spine). Their movement is as though an invisible hand were helping, causing them to glide and tumble in peculiar but graceful patterns in slow-motion. This movement appears to mimic the swaying movements of the seaweed and kelp. Only close observation reveals movement of an eye or tiny fins.


Most sources of information about sea dragons say they are found in the ocean waters of southern Western Australia, South Australia and further east along the coastline of Victoria province, Australia.  Sea dragons are protected under Australian law, and their export is strictly regulated. A 1996 assessment by the Australian government's Department of Environmental Heritage indicates "It [the Leafy Sea Dragon] is now completely protected in South Australia because demand for aquarium specimens threatened the species with extinction." Currently the specific law which protects them is called the Environment Protection and Biodiversity Conservation Act 1999.  For a February 2002 updated overview of the leafy sea dragon, see this page from the Department of Environmental Heritage site.