As fabulous, fantastical gems of evolution go, seadragons are hard to beat.
The weedy seadgragon:
"Weedy seadragon-Phyllopteryx taeniolatus" by Sylke Rohrlach - https://www.flickr.com/photos/87895263@N06/11259275943/sizes/l/in/photostream/. Licensed under CC BY-SA 2.0 via Wikimedia Commons.
The leafy seadragon, one of my favorite animals of all time:
These two species both occur in south Australian waters; the common or weedy seadragon occurs along the entire southern coast including Tasmania, while the more beautiful leafy seadragon is restricted to the southwest coast and the shallow waters of the Great Australian Bight. Their coloring, ornaments and overall resplendent frippery seem calculated to say, "Nothing here but us kelp. Yup. Boring ol' kelp." Yet to those of us who see that they are not kelp, their beauty, intricacy, and sheer existence (thank you, evolution!) are utterly mesmerizing. I once spent no less than 15 minutes fogging up the glass of a display of these creatures in an aquarium here in the States.
Until now, only these two species had ever been described, the last of which was named 150 years ago. So it came as a bit of a delightful shock when I lately saw the news that a third species has appeared: the ruby seadragon. No less surprising than its existence is its vermilion color, lack of kelpy appendages, and the depth from which it was hauled: 51 meters (167 feet).
At top is a freshly collected specimen—a pregnant male, no less—photographed on the trawl ship into which it was landed. It appears to have been photographed under less than ideal conditions. Low light perhaps, or maybe on a light box (which would explain the overexposed background and underexposed seadragon). This is the only published photograph that exists of the ruby seadgragon.
Below it is the preserved specimen of the same animal, bleached by the chemical bath into which it was plopped for science. Its eggs have also either been stripped or fallen off -- note the loss of mass under its tail.
Because this photograph is so difficult to study at the horizontal size possible on this blog, I've enlarged and rotated the image at left so you can see the detail better. Note that it possesses the same vertical body stripes as the leafy seadragon (although the ruby seadragon's stripes extend only half-way up its body, and are pink instead of white rimmed by purple), but is very different in other ways. Its body shape resembles the common or weedy seadragon more, but the weedy seadragon is much more mottled.
Although there are "enlarged spines" on the neck and back of the seadragon, "presence and shape of dermal appendages on enlarged spines unknown," the American and Australian authors of the study describing the new species write. In other words, this seadragon may have some sort of bizarre-looking mainsails as the other two species of seadragon, but for now, with so few specimens, we just don't know.
The discovery of this seadragon was unexpected, perhaps even shocking. It is the first new seadragon species in 150 years, and no one was looking for it; it was discovered by accident as part of a biodiversity survey. It appeared in the trawl nets of the University of Western Australia's Marine Futures project 2007, pulled from waters a few kilometers off the coast of southeastern Western Australia from a habitat of deep reef mixed with sandy bottom.
Without even realizing what they had (in spite of its startlingly unusual red color), expedition scientists photographed and preserved the specimen, and later accessioned it at the Western Australian Museum as a common, or weedy seadragon.
It was not until its DNA was sequenced as part of a project to study the diversity of the two known species that the scientists realized, possibly jaws agape, what they had. The DNA of this new species diverged as much from the existing two species as the two species did from each other. Genetically, it seems to be more closely related to the common or weedy seadragon than to the more splendiferous leafy seadragon. They named their new species Phyllopteryx dewysea.
At that point an all-out search was made for additional specimens, and lo, there were three already in scientific collections, the first of which was collected in 1919. These additional specimens underline the importance of dusty, foul-smelling, legacy natural history collections that many universities and natural history museums struggle to support. "Only the retention of the unrecognized Phyl. dewysea specimens in museum collections allowed for its discovery as a new species," the scientists wrote. "This highlights the significance of natural history collections as a treasury of new species, even decades after their collection."
Why did it take so long to find this seadragon? The last new species was discovered 150 years ago, and the new species is a big, beautiful, obvious fish. A lot probably has to do with its preferred depth. Though the two previously known seadragon species are common in shallow reefs, the specimen photographed was pulled from 51 m (167 feet), while two of the additional specimens were collected at 72 m (236 ft) a few kilometers offshore (the third -- the one collected in 1919 -- washed up on a beach). 150 feet is far beyond the depth accessible to recreational SCUBA divers, who usually bottom out at about 110 feet, and few people travel kilometers from shore to dive.
Its color is also testimony to the fact it probably prefers deep water. As any diver can tell you, red is the first wavelength of light to be filtered by seawater, so red animals at depth become effectively invisible.
Such deep reefs in the range of 150-1000 feet have long been overlooked because of the difficult in reaching them by scientists, a topic I wrote about before here using the example of an adorable spiny baby seabass. As the authors wrote, "The discovery provides a spectacular example of the surprises still hidden in our oceans, even in relatively shallow waters." They are ripe for exploration, and they are right here in our own planetary backyard.
Stiller J., Wilson, N.G., & G. W. Rouse (2015). A spectacular new species of seadragon (Syngnathidae), Royal Society Open Science, 2 (2) 140458-140458. DOI: http://dx.doi.org/10.1098/rsos.140458