Port Jackson shark adults are often seen resting in caves in groups, and prefer to associate with specific sharks based on sex and size. Juvenile Port Jackson sharks, on the other hand, do not appear to be social. A captive study showed that these juveniles did not prefer to spend time next to other sharks, even when they were familiar with each other (i.e. tank mates). Juvenile Port Jackson sharks have unique personality traits, just like humans. Some were bolder than others when exploring a novel environment and they also reacted differently to a stressful situation (in choosing a freeze or flight response).