Cuttlefish skimp on lunch when there’s shrimp for dinner © Pauline Billard

Cuttlefish skimp on lunch when there’s shrimp for dinner

Cuttlefish, related to squid and octopuses, learned whether they could rely on a meal of shrimp later on or if they should eat while they could.

When cuttlefish know that their favourite food will be on the menu at dinnertime, they’ll eat less for lunch, according to new research carried out at the University of Cambridge.

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Cuttlefish are a type of cephalopod mollusc and they have a wide diet that includes crab, fish, squid and shrimp, but they show definite preferences for particular foods.

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After establishing that shrimp was the favourite food of European common cuttlefish (Sepia officinalis), the researchers found that when they reliably gave the cuttlefish a meal of shrimp in the evening, they’d eat fewer crabs when they were offered during the day.

When the shrimp dinners were only provided at random, the cuttlefish would eat more crabs in the daytime as they could not predict if their favourite food would be available later on.

“It was surprising to see how quickly the cuttlefish adapted their eating behaviour – in only a few days they learned whether there was likely to be shrimp in the evening or not. This is a very complex behaviour and is only possible because they have a sophisticated brain,” said Pauline Billard, who took part in the research.

When cuttlefish hatch out, they already have a large central nervous system and are able to learn from a young age. They are capable of responding to their environment in a flexible fashion, and can adapt their hunting, mating and behaviour strategies to ensure the best possible outcomes.

In this study, they proved that they could adjust their foraging behaviour on a day to day basis to guarantee that they were eating enough, but also not missing out on their favourite foods.

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In evolutionary terms, cephalopods split from vertebrates around 550 million years ago. These findings could offer new insight into when complex cognitive ability evolved.

Reader Q&A: How do octopuses move their limbs if they have no bones?

Asked by: Toby Graham, Shrewsbury

Octopus arms work in a similar way to an elephant’s trunk, a snail’s foot and your tongue. Known as ‘muscular hydrostats’, these structures consist almost entirely of densely packed muscles.

By combining in different arrangements, the muscles can provide an impressive range of movement. When octopuses crawl along the seabed, they contract lengthwise and crosswise muscles in their arms, elongating and shortening their arms in turn. They twist their arms by contracting sets of muscle fibres that wrap diagonally around them.

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