When you think of prawns, probably the first word that comes into your head isn't "innovative". "Tasty", perhaps, or "fiddly" if you're not a fan of seafood.

The latest research does not show that prawns are secretly creative geniuses – far from it – but it does show that they can innovate in their own way. More importantly, it reveals the sorts of circumstances that trigger them to do it.

Many animals have been seen inventing new behaviours. For instance, the boars in one zoo have learned to wash their food before they eat it. The question is, what prompts animals to do it?

"The consensus is that necessity drives innovation," says Alex Thornton of the University of Exeter in Penryn, UK. "You innovate if you find it difficult to acquire resources otherwise."

He wanted to study the pressure to innovate more deeply, and for that he needed an animal that would regularly get desperate. Then he remembered a line from one of P. G. Wodehouse's Blandings novels.

The character Lord Emsworth famously garbles his words, and one of his malapropisms had stuck in Thornton's mind. "There's a point at which he refers to his niece as a 'desperate prawn', because she said earlier she's a desperate pawn in someone's game," says Thornton.

In a general sense, it's the guys who are worse off who are innovating

"It struck me that there are some species that encounter radically different environments depending on context," he says. "Prawns are one of these species."

Prawns spend much of the year in rock pools on the shoreline. These pools vary enormously in size and in how much food they contain. "At times when you go and look in a rock pool you might find 20 prawns or just a single prawn," says Thornton.

This changeable environment might force prawns to try new behaviours.

His team collected common prawns and grass prawns, and placed them in water tanks. At the other end of the tank was a piece of food for them to find.

In some cases the food was behind a barrier with a single hole in it, forcing the prawns to take a roundabout route. In others, it was under a small box that the prawn had to move.

Hungry prawns have an obvious incentive

The team tracked whether or not the prawns attempted these novel behaviours, in a range of setups. Prawns were either large or small. Sometimes they were alone, in others they were in a group of 16. Sometimes the prawns were hungry, sometimes they were full.

"In a general sense, it's the guys who are worse off who are innovating," says Thornton. "There's two big factors that could be important: size and hunger."

Small prawns might be unable to muscle their way past competitors, so might instead find creative ways to get to food. This video shows a small prawn finding its way through the barrier.

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Meanwhile, hungry prawns have an obvious incentive. In line with that, hungry prawns often turned the box over to get food, as in this video.

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Some of them also pulled bits of food out through holes in the box.

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Overall, both size and hunger drove the prawns to innovate to get food, but only under certain circumstances.

"The headline message is that which one is important depends on context," says Thornton. "If you're on your own, size is important. Small prawns tended to innovate. If you're in a group, size doesn't seem to matter and it's really hunger that drives it."

It's not entirely clear why, but Thornton says small prawns may not bother innovating when they are in a group, because if they did manage to fetch the food a bigger prawn might just steal it. This footage of a group trial illustrates what a free-for-all it is.

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The findings are published in the journal PLoS ONE.