Theory:

The fact that practically every mammal species on Earth, from antelopes to zebras, and even humans, is covered with structures known individually as 'hairs' and collectively as 'fur' is one of their most distinguishing characteristics. These hairs or furs are covering the skin of the mammal.
 
Also, the skin has specific modifications at the tips of the limbs as nails and claws. The mammal's integument is made up of hairs, furs, nails, and claws that run along the skin. In this topic, we are going to study the integument of the rabbit.
Integument (Skin):
All vertebrates have an outer protective layer covering their bodies. The integument, often known as skin, is the body's outer layer responsible for maintaining its shape. The skin is thick and covered with hairs.
 
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Various structures like hairs, claws, nails and different glands such as sweat glands, sebaceous glands, and mammary glands are derived from the skin.
 
Terms related to the integument:
  
Hair
  • Hairs originate from the epidermis and are only found in mammals. Hair serves to insulate, conceal, signal, protect, and sense the immediate surroundings in animals.
Claw
  • A claw is a sharp, thin, and curved nail of an animal's finger or toe. Claws are used by carnivorous mammals such as cats and dogs to catch and hold prey, but they can also be used to dig, climb trees, self-defence, and groom.
Nails
  • Nails protect the sensitive tips of fingers and toes.
Mammary glands
  • Mammary glands are nothing but skin glands that have been modified. In females, they secrete milk for the nourishment of the young ones after birth.
Sweat glands
  • Sweat glands perform a critical function in body temperature regulation. When the body temperature becomes too high, the sweat glands are stimulated to absorb water from the blood capillaries around them and release their secretion on the skin's surface.
  • Sweat glands also serve as excretory organs because they excrete urea dissolved in water. A beneficial salt, sodium chloride, is also excreted through the skin.
Sebaceous gland
  • A sebaceous gland is an organ that is found in the dermis. It produces sebum, an oily secretion. Sebum lubricates the skin, protecting it from friction and making it more waterproof.
Important!
The body temperature is controlled by sweat glands and sebaceous glands embedded in the skin.
Functions of the Integument:
  1. It aids in maintaining body shape.
  2. It protects the body's organs from mechanical damage. It also works as a germ-proof coating for the body, preventing bacteria and other germs from entering.
  3. Claws, horns, nails, and hooves are skin derivatives as digging tools and offensive and defensive weapons.
  4. Sweat glands in the skin help in body temperature regulation by draining sweat.
  5. The skin helps to remove metabolic wastes from the body.
  6. The skin acts as a secretory organ. For example, milk is produced in the mammary glands, and the sebaceous gland secretes sebum, an oily secretion that protects the skin and hair from moisture.
  7. It aids in the process of sexual selection. The colour and structures of the integument attract the opposite sex.
  8. The skin's sensory function is provided by fine nerve endings and unique tactile corpuscles in the integument. It is stimulated by touch, pain, pressure, temperature, etc.
  9. In the presence of sunlight, the skin can also synthesise vitamin D.
Coelom (Body cavity):
The coelom is the space between the intestinal canal and the body wall of animals.
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Coelom of vertebrate embryo
 
Rabbits belong to the coelomate family of animals. The body of the rabbit is divided into thethoraciccavity and abdominal cavity. They are separated by a transverse partition known as the diaphragm.
The diaphragm is one of the characteristic features of mammals.
The movement of the diaphragm causes breathing movements. The coelom is lined by the outer parietaland inner visceral epithelium, covering and enclosing all the organs. The thoracic cavityholds the heart and lungs, while the abdominal cavityencloses the digestive and urinogenital systems.
 
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Coelom or body cavity of rabbit and internal organs
Reference:
https://upload.wikimedia.org/wikipedia/commons/b/b0/Vetebrate_Embryo.jpg