Social animals

All whales, dolphins and porpoises are social animals, although the degree of sociability varies greatly from one species to another. Differences of behaviour have not evolved by chance. Living in close proximity to other animals has certain costs and benefits, so we can expect the group size adopted by a species to be the most suitable for its environment and lifestyle. River dolphins, for example, have a fairly simple social system, forming small groups of just a few animals, rarely more than ten. On the other hand, many of the oceanic dolphins may roam the seas in groups of thousands. Also, there can be differences within species. For example, with sperm whales, females and juveniles form groups, while adult males are solitary. Some of the reasons for living in groups include greater efficiency in searching for and catching food, benefits for mating, learning, defense and sensory integration. Now, sensory integration is the means by which each animal contributes to the information gained by the group as a whole, and this plays an important part in defense and in the search for food. For example, if one animal discovers a shoal of fish or a hungry shark, it can immediately pass on this information to the others in the group so that all may benefit. A single animal or small group may remain unaware of the food or predator and so miss a meal or suffer an attack.