Questions 13-16 are based on the following passage.

    The study of cetacean intelligence has added to our understanding of dolphin behavior. Even though cetaceans, which are marine animals including dolphins, whales, and porpoises, are widely considered intelligent species, conditions about the type and extent of dolphin intelligence have not yet been reached. However, there are several things that we do know about the ways in which dolphins communicate and behave in groups.

    Researchers study the level of communication among dolphins because communication systems can offer insight into an animal's intelligence. Dolphins produce two primary types of vocalizations called clicks and whistles. Dolphins generally use clicks for the purposes of echolocation and whistles for communication. Dolphins emit clicks as rapid broadband bursts that are sent out into their environment and then echo back, giving them information about their surroundings. Whistles differ from clicks by being sent out as narrow-band frequency modulated signals, which are for ‘communications such as contact calls. Strong evidence supports the idea that dolphins use signature whistles to identify and call to each other.

    One hypothesis called the “acoustic flashlight” hypothesis maintains that dolphins may be able to leam passively about their surroundings by listening in on the echolocative inspections of other dolphins. Scientists are researching this idea by looking at how dolphins participate in postural Pointing, an activity that humans perform when they point a finger to direct another person towards an objector location

    Communication is also an important part of how dolphins behave in groups, which can range in size from a pair of dolphins to apod of hundreds of individuals. Researchers have noticed that large packs rely on a highly organized method of communication when responding to predators, such as sharks. When a group of dolphins reacts to an unexpected disturbance, it will quickly move in near-unison to avoid the threat. In this way, dolphins rely on visual and auditory cues to communicate their location and to interpret the locations of others in the pod.


According to the passage, rapid communication enables dolphins to ....