A Small Shark With a Big Personality
Updated: Nov 5, 2021
"Personality" is no longer a trait which is only assigned to human beings. In fact, personality (defined as individual differences in behaviour which are consistent across both time and contexts) has been proven in over 200 species! Including mammals, amphibians, molluscs, birds, fishes and even insects!
What is 'Personality'?
When psychologists discuss human personality, we are defined based on 'the big 5' behavioural axes, named 1. Openness to experience, 2. Extraversion, 3. Conscientiousness, 4. Agreeableness and 5. Neuroticism.
If you want to learn more about your personality type, you can take a Myers-Briggs test.
However, in animals behaviours are defined differently. Conscientiousness and has only been found in very few animal species. Instead, generally, animal personalities are explored based upon individual differences in: 1. Activity, 2. Aggression, 3. Boldness, 4. Explorativeness and 5. Sociability (Conrad et al, 2011).
Some Sharks are more Social than Others
Researching personality in animals is a relatively new field, but becoming increasingly popular amongst scientists. So now, we have started to see studies of shark personality!
For example, a recent study proved that personality in terms of individual differences in sociability, is present in the small spotted catshark (Scyliorhinus canicula). They considered both the size of the group and each individual shark's position within the network to assess sociability, and also investigated whether individual sociability was consistent when that animal was placed in different habitats (Jacoby et al, 2014).
To do this, they tag each shark, so it could be tracked accurately in an aquarium and then watched which individuals preferred to rest together on the substrate. Sharks were considered to be associating with each other when they rested within one body length of another individual (Jacoby et al, 2014).
What they found was that individual catsharks differed in their social interactions; preferring to associate with certain, familiar individuals... Basically they had pals they preferred to be around (Jacoby et al, 2014).
Shark Friendships are a Result of Evolution
The researchers hypothesised that having consistent social partners might allow the catsharks social stability and social cohesion. This is particularly important in prey species, like the catshark, because grouping together can increase their chances of survival (Jacoby et al, 2014).
The researchers also investigated whether this sociability was consistent in different contexts, by looking at the size of groups the catsharks rested in when they were in a different kinds of habitats. They found that in simple areas, with just gravel on the ground, the sharks formed a small number of large groups, but in more three-dimensionally complex structures, like coral reefs, the sharks formed many, small groups (Jacoby et al, 2014).
This suggests that, whilst individual sharks differed in their sociability, the environment also had an impact on their behaviour. This is called "plasticity"; meaning that an animal is able to adapt based on the context to ensure its behaviour is not sub-optimal in different situations (Jacoby et al, 2014).
Imagine how lively you are in different situations- In a social situation, with lots of friends you know, you might be very active, loud and laugh a lot, but if you were in a situation where you and the same friends were taking a test in an exam hall, your behaviour would be very different. This does not mean your personality has actually changed, but that the context you find yourself in affects how you behave.
The catsharks adapt their behaviour in this way because, in a more complex habitat, they are less vulnerable to predators, but in a simpler habit, they are much more exposed. In this situation, they form large groups for safety via the "predator confusion effect". Their spotted skin provides them camouflage when they are in a group because it is more difficult for a predator to pick out an individual within the school. In a habit with more structure, which already offers them some camouflage, the catsharks were able to relax in their favoured small cliques (Jacoby et al, 2014).
Thank you to Susana Martins for allowing the use of her beautiful photography in this article.
Conrad JL, Weinersmith KL, Brodin T, Saltz JB & Sih A (2011). Behavioural syndromes in fishes: a review with implications for ecology and fisheries management. Journal of Fish Biology, 78, 395-435.
Jacoby DMP, Fear LN, Sims DW & Croft DP (2014). Shark personalities? Repeatability of social network traits in a widely distributed predatory fish. Behavioral Ecology and Sociobiology, 12:68, 1995-2003. Access online.