A good deal of dolphin and porpoise brains is devoted to processing information about sound. In the darkness of the sea, sound is also used for communication with other members of the same species. The songs of humpback whales, the low pitched boom of blue whales, the chirps and trills of the beluga and the whistles of dolphins are all means of cetacean communication. The very low-pitched sounds of the blue whales may travel hundreds of miles through the water. No one is certain how good their vision is, but dolphins can catch small objects thrown to them with ease.
Many whales stick their heads out of water and appear to be taking a look around.
The behavior is called spyhopping. They bear their young in the water. While dolphins typically stay in warmer waters, many whales migrate from cold feeding grounds to warmer seas so that their offspring can start life in warm water. Newborn calves lack a thick blubber layer and can not keep warm as easily as adults. Whale calves nurse on very rich milk squirted from nipples hidden within a slit in the mother's belly.