None. Eagles have feathers.
2
2
2 of kind
2
Beginning in the 1790s, and especially during the 19th century, fur seals were hunted because their fur was so valuable. A select few species suffered dramatic declines, but are now recovering. Most species are now protected and hunting is mostly limited to subsistence harvest (for Native Americans and Eskimos).
3-4
The fur of seals has two layers. The first layer is the closest to the body that are short, fine and very warm. The second layer are the longer fur called "guard hair' which is a waterproof layer.
Most dog breeds don't have two layers, or a double coat, of fur. 82 out of 180 breeds have a double coat of fur. According to exactly how many dogs, not dog breeds, have two layers of fur, I would not know.
Usually one, much the same as you have one layer of hair on your head, if you have hair on your head.
Dogs have fur, which is made up of multiple layers of hair.
Dogs have fur, which is made up of multiple layers of hair.
Dogs have fur, which is made up of multiple layers of hair.