Single-celled predator extends its ‘neck’ with the help of origami

The mystery of how a single-celled predator extends its “neck” by more than 30 times its overall length has finally been solved

By Michael Le Page

6 June 2024

The organism being held via two micropipettes to elongate the “neck”

Elliot Flaum and Manu Prakash/Stanford University

Imagine if your neck was so extendible that your head could reach your local shop while you sat on the sofa. That would be the human equivalent of what one single-celled predator can do – and now the long-standing mystery of how it can extend its “neck” more than 30 times the length of its “body” has been solved.

The cell membrane of this organism is folded up into a series of pleats that can only unfold and refold in one way, Eliott Flaum at Stanford University and her colleague Manu Prakash have discovered, allowing it to extend and refold without ending up in a tangled mess. “We figured most of this out by playing with a piece of paper,” says Prakash.

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

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While cell membranes are highly flexible, they aren’t elastic and cannot stretch. So how L. olor extends its neck to such a great length has been a mystery since it was first seen under a microscope in the 16th century. “We compared this to many other organisms, and it’s orders of magnitude larger in this extension,” says Prakash. “That’s the puzzle.”