Saving room for shrimp: intelligent meal selection in cuttlefish

A new study from Cambridge University researchers has revealed that cuttlefish will eat less crab during the daytime, if there is the promise of the superior tasting shrimp in the evening. This level of decision making and planning is a sign of their often underestimated intelligence.

cuttlefish
A European common cuttlefish, like those used in the new study

If you’ve ever planned to go out to your favourite restaurant in the evening or are even just preparing to treat yourself to a big take-away, then you’ve probably also made the decision to have a lighter lunch to save room for the good stuff. Well that is exactly what researchers from the University of Cambridge have found happens in cuttlefish too. They discovered that when given the choice cuttlefish will skimp out on a crabby lunch to make room for their favourite shrimp snacks for dinner. This level of foresight, planning, recognition and decision making is an example that these underestimated animals are likely as intelligent as their intellectual cephalopod cousins, octopuses and squid. It is also a fantastic example of their ability to rapidly adapt to new environments and scenarios.

Cuttlefish cravings

In the wild cuttlefish are very opportunistic predators, eating whatever they can get their hands (or more accurately suckers) on including crabs, shrimp, fish and even squid. However researchers from Cambridge University wanted to further study the feeding behaviour of cuttlefish, and more importantly explore their ability to make choices. To do this they caught 29 European common cuttlefish, Sepia officinalis, to study closely in laboratory conditions. Firstly they wanted to know which food cuttlefish preferred so as to identify which food they could use as a reward compared to others. After giving the cuttlefish some simple choices between different food types, they discovered that almost unanimously the preferred food of choice for the cephalopods was shrimp. After working this out the team then began to set up more complex experiments to discover what lengths cuttlefish would go to in order to keep eating their favourite snack.

shrimps
Much like humans cuttlefish apparently see shrimp as something of a delicacy

They began by offering a significant amount of crab during the day and a small amount of shrimp in the evenings. To start off the cuttlefish ate as much crab as possible in an effort to consume as much food as possible, as they would in the wild. But this would mean they were too full to eat all the tasty shrimp they were offered in the evening. However fairly quickly they realised that if they were getting shrimp every evening, then by not filling up on crab during the day they could fill up on shrimp later, which is exactly what they started doing. To make things more challenging the researchers then changes things up by randomly providing shrimp during some evenings and not others. When this alteration to the routine was made, the cuttlefish returned to eating as much crab as possible during the daytime, because there was no guarantee of shrimp in the evening. These results were published in the researcher’s paper which was released in early February in the journal Biology Letters.

Mind over munchies

“It was surprising to see how quickly the cuttlefish adapted their eating behaviour” according to lead author Pauline Billard, talking to Science Daily, who went on to explain that “in only a few days they learned whether there was likely to be shrimp in the evening or not” which she described as “only possible because they have a sophisticated brain”. This may seem like a bit of a stretch, after all this is something we can do without giving it much thought, but when you break it down it is actually a complex process.

intelligence
This new research suggest there is a lot more going on behind the vacant eyes of a cuttlefish than we previously believed

Firstly the fact that the cuttlefish have a favourite food is in itself a fairly advanced behaviour and suggests an ability to compare different food sources. Secondly to be able to remember the order and types of food you are being given shows a significant level of memory capacity. To then be able, after just a few days, to learn those patterns and alter your own behaviour just because you prefer one type of food over another, is actually quite impressive. Finally to be able to notice the second change and revert back to your previous feeding behaviour, despite the occasional random disturbance, shows that on at least some level there is an ability to solve problems and calculate decisions based on probability.

Intelligent inverts

Evolutionary speaking cuttlefish, along with other cephalopods, diverged from us around 550 million years ago. Like other cephalopods they also lack the classical features we associate with intelligence like a vertebrate and a long life. Yet despite these ‘setbacks’ they are still able to achieve a high level of cognitive function and perform complex behaviours. Cuttlefish in particular are perhaps the most underestimated of the cephalopods. They have the best camouflage ability of all their cousins, they have highly social mating rituals and can make decisions based on learned knowledge and probability. Earlier in the year there was also another study using 3D glasses that showed us that despite having brains wired completely different to our own, they are also capable of advanced stereopsis vision like we are. The more we discover about these amazing invertebrates and other intelligent creatures in our oceans, the more it is becoming increasingly clear that our closest intellectual rivals are probably living beneath the surface.

If you want to see another cool cuttlefish trick, then check out this clip from Blue Planet II below!


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