Cuttlefish know when it’s time for dinner (Image: Stavros Markopoulos/Getty)

Species: Sepia officinalis

Habitat: on the sea floor, in shallow temperate or tropical waters

If you struggle to remember where you left your car keys or what you ate for dinner last night, the finding that a mollusc possesses such skills might be something you would like to forget.

Yet something like episodic memory – the ability to recall when and where a particular personal experience happened – has been discovered in the common cuttlefish, the first time such smarts have been seen in an invertebrate.


Best known as one of the ocean’s masters of disguise, cuttlefish are also adept liars – cross-dressing to get their way with a mate – and have brilliant spatial memory.

Ape-like skills

The idea that they have episodic memory is more surprising, as it was assumed that a subjective sense of passing time was a necessary precursor, which animals were assumed not to have. “For a long time people thought episodic memory was only in humans,” says Christelle Jozet-Alves at the University of Caen Lower Normandy in France.

That changed when it was discovered that scrub jays can remember not only what food they have buried and where, but also when. Such episodic-like memory has also been seen in other animals such as rats and great apes.

Until now, no one had shown a similar ability in invertebrates such as cuttlefish. But Jozet-Alves suspected the creatures would make perfect candidates for testing out the idea.

Remember…or be eaten

Cuttlefish are in the precarious position of being both predator and prey and are ill-equipped to fight back if attacked. This means that they lurk in the shadows, spending more than 95 per cent of the day resting, and only nip into the open briefly to forage for food. “Their defence is to vanish or just run away. When they move, they have to be efficient and go to the right place at the right time before returning to safety,” says Jozet-Alves.

She wondered whether episodic memory might be useful to help cuttlefish optimise this foraging strategy.

To find out, Jozet-Alves’s group exploited the fact that cuttlefish develop a very strong preference for certain kinds of foods, depending on their previous experiences. Out of crab or shrimp, the cuttlefish in the study preferred crab so, when given the choice between the two, the animals would always approach the crab.

Home delivery

Jozet-Alves’s group taught the creatures to associate both foods with a visual cue: a drawing of two diamonds. In subsequent tests, the researchers delayed when they delivered the food after the cue was presented. The crab, the preferred treat, was made available in one location 3 hours after, whereas the shrimp was available in another every hour.

At first, the cuttlefish returned to both cue locations every hour, hoping to find the crab as well as the shrimp. But after about 11 trials, they began to synchronise their visits to each location with the delivery times, suggesting that they had remembered the pattern. “They haven’t forgotten the information [about the crab], it’s just that they know it’s pointless to go there because it hasn’t been replenished yet,” Jozet-Alves says.

The rapid change suggests that the cuttlefish are able to keep track of what they have eaten, where, and how long ago. It is likely that this episodic memory improves their foraging strategy and ultimately helps the cuttlefish to survive. “Cuttlefish are a species under a lot of predation pressure. In the wild, if they find a nice place where they can get their favourite food, they will come back,” says Jozet-Alves, but not until enough time has passed for stocks to be replenished, rather than taking the risk of returning to an empty food source.

The finding that cuttlefish seem to have episodic memory suggests that the ability is much more common in the animal kingdom than previously thought, says Jozet-Alves. “Maybe there’s not such a discontinuity between vertebrates and invertebrates as is often thought.”

Journal reference: Current Biology DOI: 10.1016/j.cub.2013.10.021