Here be dragons

The ruby seadragon's story of discovery is ripe with misconceptions and misinterpretations but after almost 100 years, there has now finally been a live sighting of the rare animal and the pieces of the puzzle have started to come together.

Science first became aware of the ruby seadragon when one washed up on an Australian beach in 1919. The next one wasn't found until 1956. In both cases, however, nobody realized that they were actually a distinct species.

There are three kinds of seadragons, the ruby, leafy and weedy seadragons. The latter two have distinctive leaf-like appendages attached to enlarged bony spines on their bodies. The ruby seadragon has the spines as well but lacks the leaves, making it look quite different.

As the only specimens of ruby seadragon were dead upon discovery, scientists supposed they were samples of one of the other types of seadragon and that their leafy appendages had simply been severed or fallen off after they had died.

It wasn't until 2007 that researchers got their hands on a new sample, a male carrying a brood of eggs. DNA sequencing then finally confirmed in 2015 that it was in fact a distinct species.

The thing to do now was to find one in the wild and study it. Easier said than done. The 2007 specimen had been caught in a trawl net at a depth of around 50 meters. The fishing boat had been in the Recherche Archipelago off the coast of Western Australia so the research team from the Scripps Institution of Oceanography decided to pick up the trail from there.

But diving at a depth of 50 meters is challenging, especially for longer periods of time, so the researchers relied on a small remotely-operated vehicle equipped with a camera to go diving for them. Due to rough weather conditions and other factors, they only had one day to look for the rare fish but on their second one-hour dive, they got lucky.

"It was really quite an amazing moment," said Scripps graduate student Josefin Stiller, one of the co-authors of a new study detailing their findings, published today in the journal Marine Biodiversity Records. "It never occurred to me that a seadragon could lack appendages because they are characterized by their beautiful camouflage leaves."

The team got extensive video footage of the small animals floating above the seabed as well as occasionally catching food. They had hoped to capture one of the animals, but were unable to, leaving room for more exploration and new discoveries involving this rare and unique little dragon of the sea.