Researchers from the U.S. Institution of Oceanography have finally solved the mystery of the deep-sea creature that looks like a crumpled purple sock.
“Our nickname for [Xenoturbella] was ‘purple sock’ because they look like a sock you’ve just thrown on the floor,” said lead researcher Professor Greg Rouse.
For more than half a century scientists could not work out what the creature was or where it fitted into the family tree.
Only one species from the west coast of Sweden was previously known but specimens had been unreliable, as their tissue was contaminated with prey. Early researched had accidentally analysed the DNA of what the ‘purple sock’ ate believing the mysterious creature to be a mollusc.
But four new species, one found in the Gulf of Mexico and three in the Gulf of California enabled scientists to conclude the animal belongs to one of the earliest branches of life.
One specimen recorded at a length of more than 20cm-long and has been named Xenoturbellamonstrosa, while another is called Xenoturbella churro, named after the Spanish pastry which it resembles.
Rouse said: “For the first time no one has looked at them in nature. We’ve got the first images of Xenoturbella in its own environment.
“We found one next to a dead whale carcass, and we think they like these places because there is lots of prey.”
Researchers were able to film the creatures using Remotely Operated Vehicles (ROVs) for the first time.
Xenoturbella was first described in 1949 and has no eyes, brain or gut. Everything goes out the same way it comes in through a small mouth.
The sea creature glides along the bottom of the ocean and hold their position using muscles, “so the moment they relaxed they look like a crumpled sock.
“Or deflated balloon,” said Rouse.
But the lead researcher admitted that they don’t yet “really understand how [Xenoturbella] eats”.
Rouse said: “We’ve never seen it feeding and when we open them up, we find their gut is empty.”
The bizarre creature doesn’t teeth and doesn’t have a sucking structure either. The team hopes future expeditions will what remains a “great unsolved mystery”.
