Function of Integument
1. Protection: The integument forms a covering of the body and is protective.
i. It protects the body against entry of foreign body and mechanical injuries.
ii. It protects the tissues against excessive loss of moisture.
iii. It forms protective derivatives, such as scales, bony plates, layer of fat, feathers, and hairs.
iv. In some animal the skin shows protective coloration.
v. Integument forms protective devices in some animals. Examples are: poison glands of toad, slippery skin of aquatic animals and an armor of spines of some mammals.
2. Heat production: Heat is constantly produced by oxidation of tissues, which is distributed evenly by the circulation blood and thus integument regulates heat and maintains a constant temperature in endothermal animals.
3. Food reserve: The integument stores fat in its layer as reserve food material which is used for nourishment in times of need. In whales and seals the fat of the skin forms a thick layer called blubber which is not only reserve food but also maintains the body temperature.
4. Secretion: The skin acts as an organ of secretion, glands of the skin are secretory; in aquatic forms there are secretory mucous glands, in mammals sebaceous glands secrete oil which lubricates the skin and hairs, and mammary glands produce milk for nourishment of the young. In birds uropygeal glands secrete oil for preening the feathers.
5. Excretion: The integument acts as an organ of excretion. Shedding of the corneal layer during ecdysis removes some waste substances, in mammals metabolic waste is removed from the blood by means of sweat.
6. Sense organ: The skin is an important sense organ because it has various kinds of tactile cells and corpuscles which are sensory to touch, temperature changes, heat, cold, pressure and pain.
7. Respiration: In amphibians the moist skin acts as an organ of respiration, in frogs the respiratory function of the skin is greater than that of the lungs.
8. Locomotion: Derivatives of the integument bring about the locomotion in some animals, such as the fins of fishes aid in locomotion in water, the web of skin in feet of frogs and aquatic birds aids in swimming, feathers of the wings and tail of birds are used for flying, and extension of the integument form ‘wings’ of flying lizards, extinct pterodactyls, flying squirrels and bats.
9. Skeleton formation: The skin contributes to the skeleton, it forms the dermal bones of vertebrates and also forms parts of the teeth.
10. Reproduction: The skin acts as an organ of sexual selection, it provides the feathers of birds which often have brilliant colours which are of sexual attraction, some integumentary glands of mammals produce odours for attracting the opposite sex.