Introverted fish and social spiders: unique personalities in the animal kingdom.

Character is not exclusive to humans. This truth, evident to anyone who has ever owned a cat, dog, or even a parrot, has only recently gained acceptance in the academic community. It is only in the last decade that scientists have stopped attributing individual behavioral differences in animals to statistical error; as data has accumulated, individual ethology—or behavioral ecology—has evolved into a distinct field of research.

What does "character" mean from an ecologist's perspective? It refers to behavior that varies within a species but remains stable in a specific individual under any circumstances. The range of identified character traits in animals is not as extensive as in humans: typically, populations exhibit polar behavioral models such as bold—cautious and sociable—shy (it would be more accurate to say "reclusive," but this is not about humans).

Two blue tits may engage differently in their interactions with peers. An experiment conducted in Oxford involved equipping the entire population of blue tits with sensors to track where and with whom they spent their time. Then, puzzle feeders were set up: to open one, a blue tit had to push a door in a specific way.

It was discovered that there are less sociable blue tits that form few "friends": in areas where these reclusive individuals lived, information about how to open the feeder spread slowly. In contrast, within the social blue tit groups, news traveled at record speed.

Alison Bell spent ten years observing the unassuming stickleback fish. These creatures are born either extremely bold or completely shy. The dynamics in waters inhabited by sticklebacks resemble an extreme version of a teenage social group: active extroverts push timid fish out of the group—those who cannot band together end up isolated. Ultimately, the timid sticklebacks perish without leaving offspring.

In spiders, the organization related to character traits is so complex that scientists inevitably apply political science terminology to them. The ratio of active, bold, and shy but patient spiders in a given colony forms a "group character," unique to each spider colony.

Firstly, spiders practice division of labor based on the principle of "from each according to their ability": the more active and aggressive individuals hunt prey and defend the colony from enemies, while the calmer ones weave and repair webs and care for the young. There is no gender-based division of labor observed in Anelosimus studiosus.

Here’s the story of two spider colonies: one was located below a dam, where endless insects swarmed—spider prey. The other colony was situated upstream, where only rare flies arrived. The first, well-fed colony was inhabited by brave warriors primarily focused on driving away intruders and parasites from their webs (aggressive individuals made up to 60% of the colony in this case).

Upstream, passive and compliant spiders did everything possible to make the most of their limited resources: they endlessly spun webs. "In this case, we observed a society of pacifists and egalitarians," comments the study's author, Professor Pruitt, "In each instance, the necessary balance of aggression and pacifism contributed to the survival of the colony as a whole."