The old belief that the human being is the only animal with enough intelligence and ability to develop and use tools is far from reality. A large number of species are capable of using objects to perform certain actions that they would not be able to do without them. There are species of mammals, birds, and even insects and mollusks that are capable of using tools .
chimpanzees and bonobos
Of all nonhuman primates, chimpanzees are the most sophisticated tool users, and have demonstrated this behavior both in captivity and in the wild. On the other hand, bonobos in the wild, despite their close evolutionary proximity, are not as active in this regard.
The number of uses of tools that have been observed in these animals is quite long . They wave sticks as a form of threat, hand weapon, or to avoid the attack of insects; they drag or throw them, as a form of social interaction or as a throwing weapon; they bite them for dental cleaning, or use them to clean their congeners; they use them as toys; as a support to get on or to facilitate a movement; to dig; they hit nuts and other hard fruits with them to crack them open so they can eat them; and of course, they use thin, long, peeled sticks of bark to extract termites and ants from their nests. Another common tool is the leaves, which they use as a spigot to help them drink, to hold water or to protect themselves from the rain, if they are large enough.
In studies carried out in captivity, it is observed that the ability to use tools in bonobos is not biased by age , unlike chimpanzees, where juveniles are more skilled than adults. This fact can be explained by the neoteny that bonobos present with respect to chimpanzees; an evolutionary process by which certain juvenile traits tend to be retained longer than their ancestors or closely related organisms. On the other hand, a trait that chimpanzees and bonobos do share is a greater predisposition among females to use tools compared to males.
otters
Although the use of tools is not as widespread or exuberant among otters as in primates, these graceful animals have been observed systematically using stones as tools . The main use that otters give to stones is playful, as a toy; they lie down in the water, with their abdomens out of the water, and roll them on their body or on a larger flattened rock; they juggle with them; or they drop them into the water and then dive and retrieve them.
These behaviors have been observed in at least 10 of the 13 otter species, in captivity, and in the wild in the species Lutra lutra , Lutrogale perspicillata and Pteronura brasiliensis .
However, the otter that exhibits the most complex behavior in the use of stones as a tool is the sea otter ( Enhyra lutris ) , as it not only uses stones as a toy, but also as a plate. These otters have a skin membrane behind each front leg, in the form of a fold. In it they keep molluscs collected on the seabed and take them to the surface. They also keep a flat stone, which is usually unique to each otter and is rarely replaced. When a food is too hard to open with their legs or jaws, they place the stone on their chest and hammer the mollusk rapidly to break its shell. They can hit at a speed of three hits per second.
ravens
Tool use by this group of birds is widely observed. Crows are animals with great behavioral plasticity , a high capacity for innovation, and, in general, good cognitive abilities.
The most studied corvids in terms of tool use are the New Caledonian corvids ( Corvus moneduloides ); in them the same behavior that we find in some primates of capturing insects with a long and thin stick has been observed.
But, unlike primates, among crows, a sequential process of construction and improvement of the tool has also been verified, each time longer and finer to be able to access the nest more and more efficiently. This kind of sequential use of increasingly sophisticated tools requires complex cognitive function.
Ravens also use a type of tool that, as far as we know, was exclusive to humans; the insertion and transport tool, or what we might colloquially call “ a handle or handle ”. Using a stick to hold an object, which will then be carried or used solely by handling the stick instead of handling the object.
Another fascinating behavior that has been observed in a raven, which shows the enormous capacity for innovation of these animals, is that observed by a research group in a female common raven ( Corvus corax ) from the Upie zoo, France. He used a feather of his own, which he carefully carved and prepared, to gain access to his mate’s food stash . The preparation of the tool, as in the example of the sticks, was gradual, using a trial and error method, correcting the shape of the device and the method of use, until achieving its objective.
Crickets
Among insects there are also species that make and use tools. It is relatively common – and intuitive – to observe this behavior in social insects, such as ants or termites. However, there are also solitary insects, from which great feats are not expected, that surprise by making and using tools that help them in their lives. And of all of them, one of the most fascinating is that of the crickets of the genus Oecanthus , also called tree crickets .
As in most crickets, the males ‘sing’ by emitting a sound that can be heard at a long distance, through a process called stridulation, which is produced by the rubbing of serrated structures on the inner side of the wings. Among other functions, this ‘song’ is a relevant factor in sexual selection by the female. In the genus Oecanthus , males climb trees, perch on the edge of a leaf, and emit their acoustic signals to attract females.
Some of these crickets, however, make an amplifier , by piercing leaves and emitting the ‘song’ through those holes. In fact, it has been observed that they are able to optimize the construction of these amplifiers, choosing larger sheets and making the holes in the best positions to amplify the sound. This strategy is carried out mainly by those males that have a weaker song, and that therefore, under equal conditions, would have less chance of reproducing. It is an example of the use of ingenuity to improve reproductive opportunities in cases where they would be limited by physical conditions.
octopuses
If there are animals whose capabilities can surprise us, those are the octopuses . Among invertebrates that use tools, all the observations made show an ad hoc use, that is, using the tool for a specific action, and discarding it when that function has been fulfilled. Octopuses represent an exception.
Perhaps the octopus’s most impressive tool is the construction of shelters out of halved coconut shells . This requires forward planning and great innovation, and above all an expensive and cumbersome manufacturing process before the benefit of the final creation is reaped.
Carrying the coconut shell fragments provides no immediate advantage in the process and makes locomotion difficult, which has been described as “walking on stilts”. At that time, the octopus is much more vulnerable and exposed than doing any other activity. However, once the husks are harvested, the ultimate advantage is obvious. The origin of these coconut halves is purely anthropic —coconut seeds do not usually open like this naturally—, so we can deduce that it is a very novel behavior . Although not observed, it probably stems from previous behavior using bivalve shells and the use of coconut shells is simply more advantageous because they are already clean and much lighter.
References:
Bandini, E. 2021. A Short Report on the Extent of Stone Handling Behavior Across Otter Species. Animal Behavior and Cognition, 8(1), 15-22. DOI: 10.26451/abc.08.01.02.2021
Deb, R. et al. 2020. Baffling: a condition-dependent alternative mate attraction strategy using self-made tools in tree crickets. Proceedings of the Royal Society B: Biological Sciences, 287(1941), 20202229. DOI: 10.1098/rspb.2020.2229
Finn, J. K. et al. 2009. Defensive tool use in a coconut-carrying octopus. Current Biology, 19(23), R1069-R1070. DOI: 10.1016/j.cub.2009.10.052
Gallot, Q. et al. 2019. Spontaneous use and modification of a feather as a tool in a captive common raven. Ethology, 125(10), 755-758. DOI: 10.1111/eth.12928
Gruber, T. et al. 2010. A comparison of bonobo and chimpanzee tool use: evidence for a female bias in the Pan lineage. Animal Behaviour, 80(6), 1023-1033. DOI: 10.1016/j.anbehav.2010.09.005
