Final answer:
The implied main idea is that dolphins skillfully use sonar for navigation and hunting through a process called echolocation, perceiving their environment with great care and accuracy.
Step-by-step explanation:
The implied main idea of the passage suggests that dolphins use sonar for navigation and hunting with skill and care. This process, known as echolocation, involves the emission of sound waves that reflect off objects in the environment, which are then analyzed by these animals to determine the size, distance, and even velocity of the objects. Both natural echolocation and its technological counterpart, designed for submarines and even used in cars and other systems, provide an accurate way to perceive the environment.
It can be inferred from the passage that echolocation is a sophisticated tool rather than a dangerous or lethal method. Dolphins, in particular, are described as having the remarkable ability to distinguish between objects like sharks based on the ultrasound echoes they receive, further highlighting their careful use of sonar.