Palau's Prehistoric Eel: Smithsonian makes new discovery deep in underwater cave

The oceans continue to surprise us. Even as we struggle to preserve species being lost to pollution or overfishing, scientists continue to find new species - and sometimes new "old" species. Case in point, a truly prehistoric eel found in a deep underwater cave, 115 feet below the surface, in the island nation of Palau.

Palau is a popular dive tourism location, a site for many scientific studies, and a Pacific island trailblazer having established a shark sanctuary that covers the entire island. But with all this aquatic visibility, no one had ever seen this species of eel before. A kind of half-eel, half-fish, the newly discovered creature has anatomical features that distinguish it from the current 800 species of eel today.

With a second upper jaw bone and only 90 vertebrae, features only found in fossilized specimens from the Cretaceous period, it is also unique because it has a full set of gill rakers - a cartilaginous feature found in most bony fishes - and not eels - that aid in filter feeding. The new species' lineage as a true eel was determined by examining its mitochondrial DNA.

"We believe that such a long, independent evolutionary history, [...] retention of several primitive anatomical features and apparently restricted distribution, warrant its recognition as a living fossil," said Dave Johnson of the Smithsonian National Museum of Natural History and lead author of the research team's published paper in Proceedings of the Royal Society B.

The research team likened the eel, named Protoanguilla palau, to the coelacanth, a prehistoric fish known only in the fossil record until living examples were discovered in the late 1930s. The researchers theorized that the Palau eel likely appeared 200 million years ago, at the end of the Triassic period.

Johnson emphasized, "The discovery of this extraordinary and beautiful new species of eel underscores how much more there is to learn about our planet. Furthermore, it brings home the critical importance of future conservation efforts - currently this species is known from only ten specimens collected from a single cave in Palau."