Our vast oceans still have a large extent that remain unexplored and till this day, we might not be aware of all the various species of fascinating sea creatures lurking in the dark depths and which we know nothing about. However, humans have been lucky enough to witness the exquisite beauty of this intriguing small sea creature known as the Leafy Sea Dragon.
The Leafy sea dragon (Phycodurus eques), also known as Glauert’s seadragon, is a marine fish in the family Syngnathidae and the only member of the genus Phycodurus. This species is endemic to the southern and western coasts of Australia, from Kangaroo Island to Rottnest Island, and they are closely related to seahorses and pipefish. They obtain their common name from their appearance, with long ultra-fine, delicate leaf-like appendages protruding from all over their body and the similitude they share with another creature – the mythical dragon. The purpose of these protrusions is however not for propulsion, but they serve mainly as camouflage since they resemble seaweed. Indeed, Leafy sea dragons blend perfectly well within their seaweed and kelp formations habitat, making them some of the most elaborately camouflaged creatures in the world.
This delicate creature propels itself by means of a pectoral fin on the ridge of its neck and a dorsal fin on its back closer to the tail end. Being almost completely transparent, these small fins can be hard to spot as they undulate rigorously to move the Leafy sea dragon calmly and slowly through the water, accentuating the illusion of a floating seaweed. In fact, these creatures are very poor swimmers and rely on their astounding camouflage to escape predators. Although on the small size, they are slightly larger than most seahorses, reaching about 20–24 cm (8–9.5 in) in length. Besides, they are different from seahorses but not only in appearance but in the method of locomotion also and unlike seahorses, they are unable to coil or grasp things with their tail.
Leafy sea dragons can also change color to blend in, but this capability is relevant to the sea creature’s diet, age, location, and stress level. This species feeds on small crustaceans such as amphipods and mysid shrimp, plankton, and larval fish, by sucking their prey through their long pipe-like snout with a small terminal mouth. In spite of being small enough themselves, they possess adequate vision to detect and attack individual prey (unlike large filter feeders). They have relatively large heads compared to their very small mouths, so they are able to concentrate enough pressure at their mouths to easily suck in their prey.
Similar to sea horses, Leafy sea dragon males are responsible for childbearing, however they do not possess a pouch like sea horses do, but have a spongy brood patch on the underside of the tail instead. When male sea dragons are ready to receive eggs from the female, the lower half of the tail on the male appears wrinkled. During mating, the female produces and deposits between 100 – 250 bright-pink eggs onto this special brood patch of the male, where the eggs are fertilized during the transfer. This brood patch is particularly developed by the male during the breeding season and it comprises of cups of blood-rich tissue each holding one egg and thus supplying oxygen to the eggs. Within each breeding season, male Leafy sea dragons will hatch two batches of eggs.
About 6-8 weeks after conception, the male releases miniature sea dragons into the ocean by pumping his tail until the young ones emerge – a process which takes place over 24–48 hours. The male aids the hatching of the eggs by shaking his tail, and rubbing it against seaweed and rocks. After the eggs have hatched, each baby sea dragon has a small yolk sack attached externally to it. This sac will provide the new born with food over the next few days. Beyond this time, they are on their own and hunt small zooplankton, such as copepods and rotifers, until they are large enough to hunt juvenile mysids. Sadly, only about 5% of the eggs survive and in the wild, young sea dragons are preyed upon by other fish, crustaceans and even sea anemones.
Leafy sea dragons attain a length of 20 cm after one year and reach their mature length at two years. Young sea dragons are often of a different color than adults and appear more delicate and may camouflage in different types of seaweeds. Leafy sea dragons are listed as Near Threatened (NT) on the IUCN Red List of Threatened Species. Indeed, these fragile sea creatures encounter many threats, both natural and caused by mankind. They are frequently washed ashore after storms as, contrary to their relative the seahorse, sea dragons cannot curl their tails to hold onto seagrasses for safety. Additionally, they are captured by collectors for the aquarium trade and also used in alternative medicine. In regards to these dangers, the species benefits from a specific level of protection under federal fisheries legislation as well as in most Australian states where they occur.