As we well know, or perhaps very often we forget, each of us is unique, different and special. There are those who like pizza and those who prefer lasagna, there are those who love company and there are those who prefer to be alone. These and a number of other characteristics define what is called “personality.” In us humans and the rest of primates, it has been extensively studied but the question is “are there marine animals that display a certain personality?”
One of the methods used to test personality, better defined as temperament, valid for most animal taxa, is the shy-bold continuum: differences in shy-bold behaviour are sometimes defined as differences between individuals in their willingness to take risks. It is commonly observed through basic approach/rejection behaviour with the help of an external stimulus, which can be food, a predator or a new object. For the attraction or repulsion towards a new object we speak specifically of neophilia (attraction towards what is new) or neophobia (rejection or fear of what is new).
Based on this, individuals are divided into two types:
- “Bold,” which will tend to show a greater propensity to take risks and will be attracted by the presence of new objects (neophilic);
- “Shy,” with a lower propensity and repulsion towards new objects (neophobic).
In marine mammals, such as dolphins, behavioral differences of this sort have been demonstrated and these also affect survival and community structure. In fact, individuals who exhibit novelty-seeking behaviour, show overall stronger social connectivity than those exhibiting anti-novelty behaviour. But their bold attitude does not always turn out to be very advantageous to them, making them more vulnerable to external dangers such as predators, among which humans are at the top of the list.
The presence of differences in behaviour, however, might not be surprising if you think that they are our distant “cousins” anyway, but what if this also applies to invertebrates such as some cephalopod molluscs? Despite our great surprise, animals less evolved than mammals, such as cuttlefish and octopuses, may have different types of temperament.
Recently released documentaries, like My Octopus Teacher, have already made us fall in love with octopuses – mysterious creatures almost similar to aliens that intrigue us and make us smile. They have already been recognized as very intelligent animals, able to solve puzzles of various kinds and with certain aptitude for learning also through the observation of more “expert” conspecifics, but it is also possible to demonstrate the presence of inter-individual behavioural variety through a standardized test series.
A study model is the most common octopus species, Octopus vulgaris, usually studied in captivity following an acclimatization phase in tanks. During my internship, I had the opportunity to experiment with some of the most used methodologies:
- Attack latency: a crab is lowered into the tank where the octopus is present and the speed with which it recognizes and attacks its prey is measured. It is measured diagonally, starting from the “den” the octopus constructed. Usually the higher the speed, the greater the tendency to be bold;
- Introduction of a new object: these are sometimes stimuli that serve to generate a reaction in the octopus to discriminate neophiliacs from neophobes. It is sometimes presented at the same time as food to test their reaction.
Octopus vulgaris seems to be commonly considered as a generalist, in fact, it shows a lower specialization in feeding and a greater versatility in foraging. Based on this, it will usually tend to have a poor neophobia, attacking the crab in a short time in the absence or presence of the new object, thus proving to be more courageous. Social experience, however, could sometimes influence their behaviour.
Still much progress is needed to discriminate between the individual behavioural traits that make one octopus unique over another and how this affects their survival in the underwater world.
What is still inexplicable is the invisible connection that Craig Foster himself perceives towards these animals so evolutionarily distant from us. While working with them, I almost had the feeling of being able to communicate with them only through the gaze when with their suckers they were about to touch my fingers.
We trust that science will soon answer our questions but we are now increasingly aware that we are all part of the same world, of the same whole.
A standardized battery of tests to measure Octopus vulgaris’ behavioural performance (Borrelli, Chiandetti, Fiorito)
Development of shy/bold behaviour in squid: context-specific phenotypes associated with developmental plasticity (SINN*†, GOSLING, MOLTSCHANIWSKYJ)
When personality matters: personality and social structure in wild bottlenose dolphins, Tursiops truncatus, Bruno Díaz López