New Worm Species With Glamorous Iridescent Scales Discovered in the Ocean Abyss

Researchers have identified four new species of deep-sea "worms" that feature spectacular iridescent scales on their back.

A team from the Scripps Institution of Oceanography at the University of California San Diego collected the animals, known as "scale worms," at depths of more than 3,000 feet in the waters of the Gulf of Mexico, and parts of the eastern Pacific Ocean, including the Monterey Canyon, the Gulf of California and Costa Rica, according to a study published in the journal ZooKeys.

The bizarre creatures—colloquially known as "Elvis worms" due to their shiny scales reminiscent of the King of Rock's famous sequined suits—are distant relatives of earthworms that are found in soil all over the world. The scale worms, however, are adapted to a very different habitat, having evolved to tolerate the extreme conditions of the deep sea.

Researchers often spot scale worms around the carcasses of dead whales that have sunk to the bottom of the ocean, as was the case for most of the specimens representing three of the newly identified species. The remaining species, meanwhile, was identified at a hydrothermal vent in the Gulf of California.

The new scale worms all belong to the genus, or group of species, "Peinaleopolynoe"—and this term forms the first part of their names. According to the study, the species have been dubbed P. orphanae, P. mineoi, P. elvisi and P. goffrediae.

The researchers spotted them using remotely operated vehicles (ROVs) and a submersible known as Alvin, while using DNA analysis to identify them as distinct species.

The researchers were even able to capture remarkable footage of two P. orphanae scale worms apparently fighting each other, with the help of one ROV known as SuBastian. The video was taken in November 2018, at a depth of 2.2 miles (around 11,600 feet) in the Gulf of California.

"For several years, it was a mystery as to why the scales of P. orphanae specimens were often drastically damaged, and we reasoned that it may have occurred during the collection process," Avery Hatch, a PhD student at the Scripps Research institute and lead author of the study, said in a statement.

"Now that we have observed the entertaining in situ fighting behavior of P. orphanae, we understand that these animals are actually biting off chunks of one another's scales."

The depths at which the scientists found P. orphanae form part of the so-called "abyssal zone," the portion of the ocean that is deeper than around 6,600 feet and shallower than about 20,000 feet.

This vast zone covers around 83 percent of the world's oceans and is considered to be the largest single habitat for life on Earth, according to the Monterey Bay Aquarium Research Institute (MBARI). However, it is also one of the least well-known to scientists.

Peinaleopolynoe orphanae, scale worm
Peinaleopolynoe orphanae, one of the four new species of scale worm described in the study. Greg Rouse

"It is hard to believe that the deep sea is still largely unexplored and teeming with mysterious animals waiting to be discovered," Hatch said.

In fact, some researchers think there could be more than a million unidentified species hiding in this vast realm.

"A million or more undescribed species, with biological adaptations and ecological mechanisms not yet imagined, may live within the vast volume of the deep-sea water column," MBARI marine biologist Bruce Robison, who was not involved in the research, said in a statement.

"The animals in this huge habitat make up essential links in the oceanic food web. They also provide food for important commercial species like tuna and salmon, as well as for whales, turtles, and giant squid."

The environment in the abyssal zone is remarkably uniform across the globe, characterized by darkness, very cold waters and high pressures. Thus the animals that live in the abyssal zones tend to be highly specialized.