They produce narrow-band high-frequency sound to help them navigate in water. These high-frequency sounds are used in echolocation. Echolocation is used to identify and locate prey and also avoid the predators. Marine mammals like whales and dolphin use echolocation in different manners.
Eve.......................
This is true. There are theories that scientist believe that everything become fossils. Some just aren't permanent because of the weak bone structure in most animals.
Are you referring to Murray Llewellyn Barr? :) He was the main scientist to experiment the neurons in female cats.
Hope this helps! :)