The skin of vertebrates is formed by two layers: the skin itself, or the dermis and epidermis. Dermis is well developed in mammals. It is an interweaving of connective tissue fibers.
For aquatic mammals and animals living in cold climates, the dermis plays an important role in protecting the body from hypothermia. The dermis contains the skin glands, blood vessels, receptors, and nerves that fit into them.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.