They have a reputation for being ruthless, solitary predators, but the opposite may be closer to the truth. Some sharks organize themselves into communities and subcommunities, forming long-term relationships with other sharks.
Location, sex and the length of a particular shark appear to be the most common uniting factors among blacktip reef sharks.
Sharks may bond with each other for group hunting, to reduce aggression, to avoid predation, and for other reasons.
Via Sakis Koukouvis