WILD NATURE

'Mythical' sea blob finally spotted a century after its discovery

A giant larvacean, Bathochordaeus charon, surrounded by its inner "house" (the rounded globular object in the middle of the photo) and its outer "house" (the large yellowish mucus net)

A giant larvacean, Bathochordaeus charon, surrounded by its inner "house" (the rounded globular object in the middle of the photo) and its outer "house" (the large yellowish mucus net)  ((c) 2013 MBARI)

A mysterious sea blob that looks like a psychedelic Slinky has finally been spotted, more than a century after it was first described.

The translucent, sea-dwelling invertebrate, called Bathochordaeus charon, was identified recently off the coast of Monterey, California, by scientists using a remotely operated vehicle (ROV). Though B. charon was first discovered a century ago, no one had managed to confirm its existence in all those years, Rob Sherlock, a scientist at the Monterey Bay Aquarium Research Institute who found the creature, told Live Science in an email. [See Photos of the Translucent Sea Blob]

Mysterious sea creature

B. charon belongs to a group of sea creatures known as larvaceans — normally teensy, millimeter-size creatures whose bodies resemble a tadpole's, with a large "head" (actually a trunk) and a tail, Sherlock said.

Though the sea is teeming with tiny larvaceans, the larger versions, which can have bodies extending up to 3.9 inches, are much less common. To eat, the sea blob filters food through its shimmering, parachute-like mucus "house" almost 3.3 feet in length. By waving its tail, it stirs the water and pulls particles directly into its house. Large particles get trapped and form a fine dusting of marine "snow" on the house, while the smaller particles pass through, concentrating and then funneling into a feeding tube that goes into the mouth, Sherlock said. (The tiny larvaceans also don mucus homes, but they're smaller.)

If a passing squid or fish crashes through the house, or big particles clog the feeding tube, larvaceans simply move on and build another house. Without their houses, they cannot eat, Sherlock said.

First sightings

The first report of B. charon's existence came in 1899, when professor Carl Chun of Leipzig University came across one in the south Atlantic Ocean while leading the Valdivia Expedition, a German mission aimed at exploring the deep sea. Chun believed the creature welled up from the deepest depths of the ocean, so he named the larvacean after Charon, who in Greek mythology ferries the souls of the dead across the river Styx, the researchers reported Aug. 16 in the journal Marine Biodiversity Records .

In the decades that followed, several other naturalists reported spotting giant larvaceans, though only a few were captured alive and described thoroughly. In 1936, for instance, British marine biologist Walter Garstang collected a set of giant larvaceans that differed from Chun's, and they were classified as a new species, Bathochordaeus stygius. [Marine Marvels: Spectacular Photos of Sea Creatures]

Because the two sets of specimens were similar and Chun's originals were lost to history, scientists eventually began to wonder whether Chun's originally described B. charon was actually the same species as B. stygius. One famous larvacean expert even suggested combining the two species names, Sherlock said. Part of the difficulty in capturing these creatures is that they don't fare well in the trawling nets typically used to collect specimens, Sherlock said.

Hiding in plain sight

Sherlock and his colleagues happened upon the new species when the team's ROV, called Doc Ricketts, was exploring the waters of Monterey Bay. As soon as they saw it, the crew carefully collected it in a sealed, thermally insulated container.

"Since the vehicle was recovered some tens of minutes later, the animal was alive, in fantastic shape, and we preserved it right away in order to send it to the Smithsonian," Sherlock said. "We had no idea, until we looked more closely at the specimen, that we had actually found B. charon, the species first described over a hundred years ago."

Genetics and analysis of physical features confirmed the find, Sherlock said. It was official: There really were two distinct species of giant larvacean — B. stygius and B. charon.

"It felt like Chun had finally been vindicated after years of doubt," Sherlock said.

When the team went back over videos from Monterey Bay from the past 25 years, they realized the creature had been spotted many times in the bay. Whether they dwell in places between Monterey Bay and the South Atlantic, however, remains to be seen.

Still, this mythical sea blob is fairly rare; over the course of the past few decades, biologists have seen hundreds of B. stygius, but captured footage of only a dozen B. charon individuals, Sherlock said.

Original article on Live Science .