Epidermis, Dermis, and Subcutaneous Layer
Subcutaneous Layer
Fatty tissue providing insulation and padding
Hair
Filamentous structure originating from the epidermis, providing insulation, protection, sensory input, and communication
Protection
Function of hair physically protecting the skin from UV rays, abrasions, etc.
Insulation
Function of hair providing warmth through underfur and arrector pili muscle
Secondary Sexual Character
Function of hair supporting male/male competition and female choice
Communication
Function of hair to interact with the immediate surroundings
Sensory
Function of hair to sense the immediate surroundings
Bristles
Long hairs often used for visual signals (e.g., lion's mane)
Wool
Long, soft, and usually curly hair
Guard hairs
Longer, often coarse hairs that complement underfur
Epidermis
Outer layer of dead keratinized cells
Mammary glands
Specialized epidermal glands in females that produce milk
Spines
Stiff and enlarged guard hairs (e.g., porcupines)
Dermis
Connective tissue with blood vessels and nerves
Sebaceous glands
Glands associated with hair follicles that secrete oily products
Eccrine glands
Glands not associated with hair that secrete watery secretions to help cool through evaporation
Apocrine glands
Glands that produce viscous fluids acting as chemical signals (pheromones)
Eumelanin
Hair pigment that produces shades of black or brown
Pheomelanin
Hair pigment that produces shades of red or yellow
Angora
Hair that grows continuously to produce long shafts, may or may not be shed
Definitive
Hair that grows to a fixed length then falls out (e.g., single coated dogs)
Scent glands
Modified sebaceous or apocrine glands that use pheromones for communication signals
Vibrissae
Sensory 'whiskers' that are long and stiff
Forensics
The use of scale patterns in hair for identification purposes