What is Not a Whale
Whales were once though to be very large fish. Sharks, tuna or other big fish do look a lot like whales; they have a streamed lined shape, similar kinds of fins, and they share the same underwater environment. But fish are not the same as whales. In fact, whales are more closely related to cows or goats that they are to fish. Whales are mammals – this means that they have to come to the surface to breathe air into their lungs, while fish use their gills to take the oxygen they need directly from the water. Whales give birth to live babies, one-at-a-time, while fish lay eggs in the hundreds or even thousands,. But the quickest way to tell whether you’re looking at a fish or a whale is to check out the tail. Whale tails are horizontal, and a whale swims by moving its tail up and down. Fish tails are vertical, and a fish swims by moving its tail side-to-side.