A, An ancestor of whales had legs. Hope i helped! :D
Answer:
Bones are organs composed of hard living tissue providing structural support to the body – it's scaffolding. It is a hard matrix of calcium salts deposited around protein fibers. Minerals make bone rigid and proteins (collagen) provide strength and elasticity. ... The outer layer of bone is called Cortical bone.
Because whales live in the ocean, many people think they are fish. But do you know that whales and dolphins are not fish? They are mammals. People are mammals too. Mammals are the group of animals that breath air using lungs, give birth to live young (rather than laying eggs), and feed their young with mother’s milk. All animals, including people, need oxygen, a chemical found in the air and in water. Fish use their gills to take oxygen from the water that they live in. But people get the oxygen we need by breathing air, using our lungs. Whales and dolphins use their lungs to breathe air also.
That’s one reasons why they come to the surface of the ocean. Sometimes they lie right at the surface of the water, with just a part of their back sticking out. Look closely at a picture of a whale or dolphin; can you see a nose on the whale? You can’t, because whales don’t have noses like you and me. Instead they have a hole – called a “blow hole” – on top of their heads. Sometimes when a whale breathes air out of its blow hole, it shows up as a spray or mist – called a “spout” – that can be seen many miles away. Blow holes are surrounded by muscles that keep the hole closed when the whale or dolphin is under water and open it when the animal is at the surface and needs to breathe.
In fact, some of the animals have two blow holes next to each other and others have only one. So when you see a picture of a whale, see if you can tell the difference. Pilot whales and dolphins have one blow hole; humpbacks, minkes and right whales have two
