Bizarre Ruby Seadragon Filmed In the Wild for First Time

Researchers have captured the first-ever field sightings of the newly discovered ruby seadragon (Phyllopteryx dewysea). Scripps Oceanography/UC San Diego

In the waters off southern and western Australia, there be dragons. For decades, scientists have known about two of them: the weedy and the leafy seadragon, fish covered in preposterous arrays of foliage-like appendages that allow them to blend into the kelp-covered seafloor.

But they are not alone. In 2015, researcher Greg Rouse at the Scripps Institution of Oceanography and colleagues described a new species, the ruby seadragon, using dead specimens found in museums and later pulled up from trawls. Now, the team has spotted one alive in the wild for the first time, as they describe in a study published January 13 in the journal Marine Biodiversity Records.

The ruby seadragon (Phyllopteryx dewysea), as its name suggests, is a red, foot-long beast that lives in deep waters off the Recherche Archipelago, a cluster of islands off Western Australia. The team filmed the animal by lowering a camera-mounted remote operated vehicle more than 160 feet to a seafloor dominated by deep-sea sponges. They observed two ruby seadragons for 30 minutes and watched as one snapped up and ate a little crustacean.

Among the most interesting features of the ruby seadragon is that it appears to have a prehensile tail. Its relatives, seahorses and pipefish, have such grasping tails, which allow the animals to hold onto vegetation in strong currents. But the other seadragons don't. Although the team didn't see the creature using its tail, they think it likely employs it for the same reason.

Other related species, such as pipefish and seahorses, often possess prehensile tails, says David Booth, a marine ecologist at the University of Technology Sydney, who wasn't involved in the study. It appears that the ruby seadragon inherited this trait from its ancestors, whereas the weedy and leafy seadragon lost it, he adds.

The animal lacks the appendages of its fellow seadragons. Rouse thinks its smoother profile protects it from being buffeted by strong currents. "It was really quite an amazing moment" when the team first spotted the creature, said Scripps graduate student and study co-author Josefin Stiller. "It never occurred to me that a seadragon could lack appendages because they are characterized by their beautiful camouflage leaves." Rouse added that its red color allows it to appear inconspicuous; in the deep waters where it lives, red light cannot penetrate and thus they appear dark.

Rouse says the study shows the importance of continued exploration of life in the ocean. If a distinctive-looking "fish like this that hadn't been found, there are probably a lot of things yet to be" discovered out there, he says.

The ruby seadragon is found at depths of more than 150 feet below the surface. Scripps Oceanography/UC San Diego


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