Squid eat with foresight

There are also representatives of the clever squid in the North Sea. (Image: Pauline Billard)

Amazing: humans and squid adapt their eating habits to future prospects in a similar way, suggest study results. When a delicious dinner is waiting for us, we don’t fill our stomach with ordinary bread beforehand. Similarly, the clever cephalopods are reluctant to hunt for rather stale crabs if they know that there are delicious shrimps in the evening. This forward-looking behavior once again demonstrates the astonishing intelligence of the bizarre sea creatures, the scientists say.

Scrawling arms with suction cups, three hearts, blue blood … Many features of the squid differ significantly from those of the vertebrates. The reason for this is that the cephalopod line of development separated from that of our ancestors about 550 million years ago. Amazingly, however, they still have a property that connects them even to the most highly developed representatives of mammals: squids have a complex nervous system that enables them to perform complex cognitive functions. Squids can learn and solve problems, have already shown various studies. The study by researchers led by Pauline Billard from the University of Cambridge now proves another astonishing ability: squids develop expectations for the future based on experience and adapt their behavior accordingly.

Delicious shrimp in mind

The researchers carried out their studies on the common squid (Sepia officinalis), which is also widespread on the coasts of Europe. It is a representative of the ten-armed octopus, which is up to about half a meter long and can weigh up to four kilograms. With their tentacles, the cephalopods cleverly capture various marine animals – such as fish, crabs and shrimps. As part of their study, the researchers first examined whether the animals had certain feed preferences. To test this, they presented their test animals with young beach crabs and shrimp of about the same size at the same distance. This showed that squids have a strong preference for shrimp.

In the following experiments, the researchers then investigated the extent to which this preference shapes the behavior of animal gourmets. First, they recorded how many crabs their experimental animals normally ate when there were no shrimp. The researchers then got their experimental animals used to evening luxury: there were always delicious shrimps at the same time.

“Tinti” plans reliable festive events

As the evaluations of the feed quantities showed, this offer had a significant effect on the consumption of crabs: During the day, the squids ate significantly less from the beach crabs than usual. This changed, however, if the animals could not rely on a feast waiting for them in the evening, further experiments showed. If the researchers only supplied the squids with shrimps on randomly distributed evenings, they would eat more crabs again during the day. According to the researchers’ interpretation, the animals were no longer able to plan due to the random provision of their favorite food and therefore preferred to make sure that they got their daily ration of food by eating the crabs. “It was surprising to see how quickly the squids adapted their eating behavior to the current rules: in just a few days, they realized how likely it was that shrimp would be served in the evening. This is an astonishingly complex behavior that is only possible through sophisticated brain functions, ”summarizes Billard.

Her colleague Nicola Clayton from the University of Cambridge concludes: “This flexible foraging strategy shows that, based on previous experience, squid can adapt quickly to changes in their environment. This discovery could shed new light on the evolutionary origins of such complex cognitive skills, ”said the scientist.

Source: University of Cambridge, professional article: Biology Letters, doi: 10.1098 / rsbl.2019.0743

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