the skin and its accessory organs.

The outer covering of the body composed of the SKIN and the skin appendages, which are the HAIR, the NAILS; and the SEBACEOUS GLANDS and the SWEAT GLANDS and their ducts.

the skin and its appendages

The skin and its derivatives (hair, nails, feathers, horns, antlers, and glands), which in multicellular animals protect against invading foreign microorganisms and prevent the loss or exchange of internal þuids. PICTURE

In zootomy, the integumentary system is often the largest organ system of an animal by surface area, comprising skin, hair, feathers, scales, nails, sweat glands and their products (sweat and mucus). It distinguishes, separates, protects and informs the animal with regard to its surroundings. Small-bodied invertebrates of aquatic or continually moist habitats respire at their outer layer (integument).