Observations of the behavior of octopuses living near Australia have shown that females often drive away too annoying males by throwing algae, shells or just sand from the bottom at them.
Video recordings taken at sea off the coast of Australia have shown that octopuses can deliberately throw objects at a target and often even hit. In most cases, this behavior is displayed by females, and often it is directed at males who are acting too intrusive. This is discussed in an article by scientists from the University of Sydney, presented in the bioRxiv open preprint library.
Since 2015, Peter Godfrey-Smith and his colleagues have been monitoring the life of the octopus Octopus tetricus in Jervis Bay on the east coast of Australia. One of the sections of its bottom is very convenient for setting up shelters, and octopuses gather there in large numbers. According to New Scientist magazine, this place even bears the informal name "Octopolis" (Octopolis).
Underwater video cameras installed in Octopolis recorded many types of octopuses' behavior: fights, courtship and … throwing objects. True, it does not happen exactly as in people. The animal uses a shell, seaweed, or picks up debris from the bottom, then brings it to its siphon and directs a stream of water at it, which carries the object away. The distance of such a "throw" can reach several body lengths of the octopus itself.
At first, scientists believed that this is a very common behavior that occurs when making shelters at the bottom or discarding food waste. However, over the years, having accumulated more videos, Godfrey-Smith and his colleagues have made sure that such throwing is aimed at a specific goal and often reaches it. So, one of the observations recorded how a female octopus 10 times in a row threw objects at a male neighbor, who had previously tried to mate with her.
Several such cases were noticed, a couple of times the males recognized the female's intentions at the moment when she "picked up" an object from the floor - and hid, without bringing the matter to a throw. In addition, scientists noted that when digging for shelters, animals use the two front tentacles, and when throwing - adjacent to them. There was also a case of throwing using only one tentacle - similar to how we throw a frisbee plate.
The authors note that purposeful throwing of objects has so far been noticed only in some highly developed animals, such as bears or chimpanzees. Primates can use throws even for hunting. But whether octopuses act this way is not yet clear. Scientists noticed two shells hitting the fish, but at least one of them was accidental. It is possible that octopuses are throwing more often than they seem. After all, they are capable of using the stinging parts of jellyfish as a poisonous weapon.