Think about in case your neck was so extendible that your head may attain your native store whilst you sat on the couch. That will be the human equal of what one single-celled predator can do – and now the long-standing thriller of the way it can lengthen its “neck” greater than 30 occasions the size of its “physique” has been solved.

The cell membrane of this organism is folded up right into a collection of pleats that may solely unfold and refold in a technique, Eliott Flaum at Stanford College and her colleague Manu Prakash have found, permitting it to increase and refold with out ending up in a tangled mess. “We figured most of this out by enjoying with a bit of paper,” says Prakash.

Lacrymaria olor is a single-celled organism, or protist, that lives in contemporary water and hunts its prey with its terribly extendible neck-like protrusion. Its title means “tear of a swan”, after its swan-like neck and tear-shaped physique.

Whereas cell membranes are extremely versatile, they aren’t elastic and can’t stretch. So how L. olor extends its neck to such a fantastic size has been a thriller because it was first seen below a microscope within the sixteenth century. “We in contrast this to many different organisms, and it’s orders of magnitude bigger on this extension,” says Prakash. “That’s the puzzle.”

He and Flaum turned intrigued after they noticed L. olor in samples they collected from a swamp six or seven years in the past, they usually got down to resolve the thriller. Flaum used various totally different methods to picture the outer construction of L. olor and its internal cytoskeleton, manufactured from buildings known as microtubules. “We tried many alternative methods of it to grasp what was occurring,” she says.

This revealed that the cell membrane of L. olor is folded into 15 pleats, and every pleat spirals across the cell, forming a helical construction. Prakash calls this folding sample “curved crease origami”, or “Lacrigami”.

However how does L. olor unfold and refold this large space of cell membrane with out getting right into a tangle? What Prakash and Flaum labored out is that due to the way in which the pleats are stabilised by bands of microtubules related to them, a complete crease can’t unfold suddenly. As an alternative, just one level of a crease can unfold or refold at any time.

As these factors transfer in parallel up every of the 15 creases, the cell membrane unfolds in an orderly method, extending the neck. Reversing the method shortens the neck.

“As an alternative of randomly folding, like if you happen to had been to crumple paper, it has a guiding rail for it to fold again in the identical approach each time,” says Flaum.

The folding and unfolding is powered by the beating hairs, or cilia, that cowl your entire floor of the cell, says Prakash. It requires vitality to unfold in addition to refold, not like a spring, however wants little or no as a result of cell membranes bend simply.

So far as he is aware of, nobody has found this folding sample earlier than. “Once we figured this out, I’d at all times thought that anyone enjoying with paper would have found this origami,” says Prakash. “It’s fairly easy.” Anybody could make it with a bit of paper and little bit of tape, he says.

“The intelligent origami design of its neck makes cilia efficient for high-speed, long-range searching,” write Leonardo Gordillo and Enrique Cerda on the College of Santiago in Chile in an accompanying article. “The origami-like protrusion mechanism recognized by Flaum and Prakash has the potential to encourage new methods in soft-matter engineering.”

Certainly, Prakash and Flaum at the moment are engaged on creating medical robots based mostly on “Lacrigami”. “When you had a small micro-robot in a really small area, and it may all of a sudden lengthen, that might be vastly helpful in microsurgeries,” he says. “However we did this work as a result of it’s simply stunning and a thriller to unravel. We had no considered it being helpful in any approach.”