Integument And Its Function

Integument or skin is the outer protective covering of an animal. It basically consists of two layers:-

1. Epidermis is basically made up of stratified epithelium and it again consists of two layers which are outer stratum corneum and inner stratum germinativum.
2. Dermis is the inner thick layer which is mainly made up of fibrous connective tissue. It consist of blood vessels, muscle fibrous, nerve fibrous, chromatophores (color giving cells), fat cells etc.

Function of Integument

1. Protection
   Skin is outer covering of animal so it is responsible for protecting the internal organs from injuries. Skin also prevents the entry of germs in the body.
   Structures present in the skin like scales, feathers, hairs etc. reduce the force of impact/ injury. Skin derivatives such as claws, nails, horns, spines etc. are used for offense and defense.
   Chromatophores present in the dermis of skin are responsible for camouflage (changing color with respect to environment). Thus, protecting them from enemies.
2. Temperature Regulation
   Skin derivative such as scales, feathers, fur etc. prevents the loss of body’s heat. Sweat glands present in many mammals helps to produce sweat that offers cooling by sweating. Fat layer present in the dermis of skin acts as an insulating layer, thus preventing loss of body’s heat.
3. Food Storage
   The fat layer present in the skin acts as reserve food which can be utilized during the time of requirement.
4. Secretion
   Skin consist of number of glands which are responsible for various secretion:-
   • Mucus gland present in fish and many amphibians secrets mucus which makes their body moist and slippery.
   • Sebaceous gland present in skin of many mammals secret an oily secretion called sebum which lubricates the skin and hair. Sebum also has bactericidal and fungicidal effect .
   • Mammary gland present in mammals secret milk for their young ones.
   • Scent gland present in many animals helps to attract opposite sex for mating.
   • Ceruminous glands present in auditory canal secret a waxy substance called cerumen which prevents the entry of small insects into the ear.
5. Excretion
   Excess of waste materials like urea, ammonia, ammonium ions (NH₄)⁺ , excess salts, some water etc. get excreted through the skin along with the sweat during sweating. Periodic shedding of skin (ecdysis) found in many reptiles also helps to get rid of waste materials.
6. Sensation
   Skin is one of the important sense organs nerve endings sensitive to touch, temperature, pain, pressure, etc. are present in the dermis of skin.
7. Respiration
   Moist skin found in many amphibians are responsible for exchange of gases (cutaneous respiration).
8. Locomotion
   Skin derivatives like fins, feathers, web etc. present in various animals are responsible for locomotion.
9. Sexual Selection
   Attractive skin coloration, feathers etc. helps to attracts opposite sex for mating .

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