RESEARCH: How do balls of worms untangle? It’s in the way they move!

How do balls of worms untangle? Harry Tuazon of the Georgia Institute of Technology in America has found that a ball of worms can untangle in milliseconds with a corkscrew wiggle.

What does this mean? And why is it important to know?

Researcher Harry Tuazon studied California Blackworms (Lumbriculus variegatus). He found that they tangle themselves into a ball to preserve moisture during droughts. He calls these ‘balls’ of worms knotted ‘worm blobs.’ In the wild, these balls can have up to 50,000 individual worms.

California Blackworm (Source: Harry Tuazon, Georgia Institute of Technology)

When Harry Tuazon shone an ultraviolet (UV) light on a twisted worm blob, he was surprised to see them untangle so quickly.

The New Scientist magazine reported in April 2023 that Tuazon and his colleagues wanted to understand how the worms could untwist and untangle in milliseconds – far more rapidly than forming the ball. First, the research team studied 20 worms in a ball to see how they wrap around each other. They also put the worms in shallow water, shone UV light on them, and filmed them, manually tracking the trajectory of each worm’s head.

They sought assistance from university mathematicians who specialize in knot theory to help them solve the worm problem. The mathematicians constructed a mathematical model and ran computer simulation exercises to determine how each individual worm got into a worm blob and how each individual worm got out of a worm blob. 

They found that, when it needs to, such as when it is threatened, each worm can untangle extremely quickly due to the way it moves – the way it wiggles or wriggles or writhes.

The California Blackworm has a special way of moving. It moves in a helical wriggle. The helical wriggle is a corkscrew motion. The worm uses a different corkscrew motion to get into a worm blob and to get out. To get into a blob, or ball, the worm uses a slow motion, and to get out, it uses a rapid motion in a different direction – either a left turn or a right turn.

One of the mathematicians, Vishal Patil at Stanford University in California, said that the worm repeats a corkscrew motion in one direction for a while and then abruptly switches direction to untangle itself. Moving quickly alternating between corkscrewing left then right, then left, then right, and so on, leads to efficiently disentangling itself from the blob. When all the worms are doing this at the same time, the blob is completely untangled.

The reason that this is important is that it has shown scientists that a complex mathematical problem can be solved. “If worms can solve this problem, so can we,” said Vishal Patil.

Understanding how a worm moves when not threatened, and when threatened, from forming a ball to getting out of a ball, entangling and untangling, may help researchers with real-life human problems. For example, Antoine Deblais at the University of Amsterdam in the Netherlands thinks it might help humans understand material filaments and how tangled threads and knots could, in the future, move themselves to become untangled. 

Journal reference: Science DOI: 10.1126/science.ade7759

California Blackworm (Source: Harry Tuazon, Georgia Institute of Technology)

California Blackworm (Source: Harry Tuazon, Georgia Institute of Technology)

Photographer: Harry Tuazon, Georgia Institute of Technology


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