The squid were able to count to five.
Squid-pharaohs count of potential prey to choose a more promising group of shrimp to attack.
Laboratory experiments have demonstrated their ability to count to at least five, what tells the article of Chinese biologists, published in the journal Proceedings of the Royal Society B.
The ability to assess the size of potential food sources and to select the richest have even simple slime mold. Predators it is especially useful because it allows you to quickly choose a better victim and not to expend forces in vain. It is shown that a highly developed cephalopods (octopus, squid) are able to assess prey size. And in the new work, researchers at the National Tsinghua University Chang-Yang (Tsang-I Yang and Chuan-chin Chiao (Chuan-Chin Chiao) demonstrated that they enjoy and the ability to account.
The authors experimented with 54 species of squid-the pharaohs Sepia pharaonis, born in the laboratory, under months of age and have not received any prior training. In aquariums to them, the scientists lowered a transparent box with two compartments divided by the wall space, which allowed the squid to approach only to one of the branches, right or left. Placing them in different number of crustaceans, is the usual prey of these animals, scientists have studied how they exercise choice.
Experiments have shown that the comparison of several shrimp one is not causing squid any difficulties, and they confidently rush to the tank with a richer prey. Only slightly more complicated was given them options that require a more accurate account: after some hesitation, molluscs significantly more often chose the container with the two shrimp against one, three against two etc.
While dead or small prey was considered less interesting, and a couple of dead crustaceans squid prefer one living, and a few small and one large. Only a feeling of saturation, they could choose a small shrimp instead of one large. These results demonstrate that squid is able to “understand” the concept of number and the choice of extracting from them is determined by its quality and quantity, as well as the predator. However, scientists have used in experiments no more than five shrimp for each tank drawer, so that the question as to what number of able to count squid, remained unresolved.
