CLASSIFICATION OF RABBIT
Class- Mammalia
Order- Lagomorpha
Genus- Oryctolagous
Species- cuniculus
· Rabbit is a member of order Lagomorpha that are typical examples of gnawing animals with two pairs of upper incisors.
1. Distribution: It is cosmopolitan in distribution.
2. HABIT
a. Feeding habit:
a. Feeding habit:
· It is herbivorous animal as well as Coprophagus or refection, i.e. feeding upon their own excreta during starvation.
· It is a fossorial animal, i.e. digging mode of life which digs the hole which is tunnel-shaped with many openings outside for entry or exit.
· Its burrow or tunnel of rabbit is known as a warren.
· This animal is crepuscular i.e. active during dawn and dusk and gregarious i.e. live in groups.
· It is a Polygynous and polygamous animal i.e one male life in the company of several females.
· At the time of danger young ones shift to the safer place by mother and death young ones are immediately removed from the burrow.
· They have a wide field of vision, an acute sense of smell and hearing.
· They are Homeothermic.
· Its Average life span is 7-8 years.
· It breeds four times a year.
· Female attain maturity at the sixth month.
· Each litter comprises 5-8 young ones.
· It is a fossorial animal, i.e. digging mode of life which digs the hole which is tunnel-shaped with many openings outside for entry or exit.
· Its burrow or tunnel of rabbit is known as a warren.
· This animal is crepuscular i.e. active during dawn and dusk and gregarious i.e. live in groups.
· It is a Polygynous and polygamous animal i.e one male life in the company of several females.
· At the time of danger young ones shift to the safer place by mother and death young ones are immediately removed from the burrow.
· They have a wide field of vision, an acute sense of smell and hearing.
· They are Homeothermic.
· Its Average life span is 7-8 years.
· It breeds four times a year.
· Female attain maturity at the sixth month.
· Each litter comprises 5-8 young ones.
Differences between Rabbit and Hare
| Rabbit | Hare |
|---|---|
| They live in Tunnels | They live in Shrubs |
| They are gregarious | They are solitary |
| Their snout is pointed | Their snout is blunt |
| External pinnae are smaller | External pinnae are larger |
| They become matured sexually at 6 a month | They become matured sexually at 1 year |
| Body length is longer | Body length is shorter |
| Their posterior legs are smaller and can not move fast | Their posterior legs are larger and can move fast |
| Body colour is sandy | Body colour is grey or brown |
3. EXTERNAL FEATURES
· Body is elongated, pointed anteriorly, broad posteriorly and bilaterally symmetrical.
· Body is elongated, pointed anteriorly, broad posteriorly and bilaterally symmetrical.
· Its length is about forty cm from mouth to anus.
· It is adapted for leaping, walking and fossorial life.
· Entire body is densely covered with hair or fur.
· It is adapted for leaping, walking and fossorial life.
· Entire body is densely covered with hair or fur.
· Its body temperature is about 38.8°C.
· Colour is dusty brown in wild rabbit with white patches under the tail.
· Body is divisible into head, neck, trunk and tail.
· Colour is dusty brown in wild rabbit with white patches under the tail.
· Body is divisible into head, neck, trunk and tail.
a. Head
· Head is large, pear-shaped.
· The anterior part of the head is pointed to form a snout or muzzle.
· Head bears mouth, vibrissae, external nares, eyes and external ear.
· Mouth is subterminal and in form of a transverse slit bounded by upper and lower lips.
· Upper lip is divided by a vertical median cleft into right and left halves. Such lip is called Cleft lip or Hare lip.
· At the sides of the snout are long stiff sensory hairs called Vibrissae or Whiskers. These are important for tactile sensation.
· The external nares open into the nasal chambers and is covered with thin hairless skin called Rhinarium (for smell)
· Eyes are large, laterally placed on the head, oval with a round pupil. They are protected by upper and lower eyelids. third eyelid or nictitating membrane is present.
· Two long erect external ears pinnae are present in the upper part of the head which can be moved in all directions independently to receive sound. On the alert condition, two ear pinnae are held upright but laid down when frightened and running condition.
· Head is large, pear-shaped.
· The anterior part of the head is pointed to form a snout or muzzle.
· Head bears mouth, vibrissae, external nares, eyes and external ear.
· Mouth is subterminal and in form of a transverse slit bounded by upper and lower lips.
· Upper lip is divided by a vertical median cleft into right and left halves. Such lip is called Cleft lip or Hare lip.
· At the sides of the snout are long stiff sensory hairs called Vibrissae or Whiskers. These are important for tactile sensation.
· The external nares open into the nasal chambers and is covered with thin hairless skin called Rhinarium (for smell)
· Eyes are large, laterally placed on the head, oval with a round pupil. They are protected by upper and lower eyelids. third eyelid or nictitating membrane is present.
· Two long erect external ears pinnae are present in the upper part of the head which can be moved in all directions independently to receive sound. On the alert condition, two ear pinnae are held upright but laid down when frightened and running condition.
b. Neck
· Neck of rabbit is short, quite flexible and well demarcated.
· Neck of rabbit is short, quite flexible and well demarcated.
· This helps in fast running, burrowing and taking long leaps.
· Neck also helps the head to move in all directions.
· It does not contain coelom and viscera.
c. Trunk
· Trunk is differentiated into narrow thorax anteriorly and broader abdomen posteriorly which are separated internally by diaphragm.
· Along the ventral surface of the trunk in females, there are 4-5 pairs of small teats or nipples or mammae through which the mammary glands open. Nipples are rudimentary in males.
· Possesses two pairs of limbs which are pentadactyl:
· Trunk is differentiated into narrow thorax anteriorly and broader abdomen posteriorly which are separated internally by diaphragm.
· Along the ventral surface of the trunk in females, there are 4-5 pairs of small teats or nipples or mammae through which the mammary glands open. Nipples are rudimentary in males.
· Possesses two pairs of limbs which are pentadactyl:
a. Forelimbs:
· It is shorter than the hind limb.
· It consists of 3 parts:
- Upper arm or brachium
- Forearm or antebrachium
- Hand or manus
· The innermost digit is called pollex.
· Forelimbs are used for digging, leaping and absorbing the shock during leaping.
· The digital formula of the forelimb is:- 2, 3, 3, 3, 3
· The digital formula of the forelimb is:- 2, 3, 3, 3, 3
b. Hind limbs:
· It is much longer than forelimb and adapted for walking and leaping.
· It is much longer than forelimb and adapted for walking and leaping.
· It consists of three parts- thigh or femur, shank or crus and foot or pes.
· Foot is further divided into– ankle or tarsus, sole or metatarsus and four clawed toes.
· Hallux or first clawed toe is absent.
· The digital formula of hind limb is:- 0, 3, 3, 3, 3
· Hallux or first clawed toe is absent.
· The digital formula of hind limb is:- 0, 3, 3, 3, 3
d. Anus:
· It is present just under the base of the tail as a small rounded opening.
· On either side of the anus hairless depressions, the perineal pouch is present where a perineal scent gland opens as a small papilla.
· On either side of the anus hairless depressions, the perineal pouch is present where a perineal scent gland opens as a small papilla.
· This gland gives the strong odour of characteristics of rabbits.
e. Urinogenital aperture:
· It is present only in a male rabbit in front of the anus at the tip of a small penis.
· It is present only in a male rabbit in front of the anus at the tip of a small penis.
f. Testes:
· They are present in the scrotal sacs which are located on either side of the penis.
· In females, slit-like urinogenital aperture or vulva is present at the base of the clitoris which is homologous to the penis of males.
g. Tails
· A short bushy tail is present at the posterior end of the trunk.
· A short bushy tail is present at the posterior end of the trunk.
· It is usually upturned and serves to transmit danger signals, also acts as a balancer while leaping.
Skin of Rabbit
· Its skin is soft, thick, dry and covered with a thick fur called pelage.· It is highly glandular but no mucous glands are present.
· Functions: protective, sensory, insulating. Not related to respiration.
· The skin consists of two layers: Epidermis and Dermis
1. Epidermis:
· It is the outer thin stratified keratinized squamous epithelium.
· It is the outer thin stratified keratinized squamous epithelium.
· It is ectodermal in origin.
· It is non-vascular.
· It is composed of 5 layers:
1. Stratum corneum
· It is the outermost layer of the epidermis, which is composed of flattened, dead and cornified cells due to deposition of Presence of keratin.
· It is thicker at the sole and palm.
· It is composed of 5 layers:
1. Stratum corneum
· It is the outermost layer of the epidermis, which is composed of flattened, dead and cornified cells due to deposition of Presence of keratin.
· It is thicker at the sole and palm.
· It constantly flakes away and prevents mechanical injuries and fungal as well as bacterial infection.
2. Stratum lucidium
· In this layer nuclei of cells are absent but eleidin is present in this layer.
3. Stratum granulosum
· It has abundant granules and acquire the keratohyalin and developed especially in palms and feet.
4. Stratum spinosum or transitional layer
· This layer is made up of several layers of polyhedral cells.
· These cells are gradually pushed outwardly and become flattened and keratinized.
5. Stratum basale or germinativum
· It is the innermost single layer of columnar cells on the basement membrane.
· It is formed by the underlying dermis layer.
· It constantly produces new cells by mitotic division.
· It constantly produces new cells by mitotic division.
· All the glands and keratin structures are formed from this layer.
· Notes: Claws are derivatives or modifications of the epidermis. (IOM)
· Epidermis doesn't possess blood vessels but has nerve fibres.
· Has melanocytes (melanin-containing cells)
· Notes: Claws are derivatives or modifications of the epidermis. (IOM)
· Epidermis doesn't possess blood vessels but has nerve fibres.
· Has melanocytes (melanin-containing cells)
2. Dermis:
· It is mesodermal in origin.
· It is composed of fibrous connective tissue, smooth muscle fibres, blood vessels, nerve fibres, adipocytes.
· Various sensory endings, hair follicles, sweat glands, sebaceous glands are present in the dermis.
· Pigment cells present in the outer layer of the dermis contain melanin which protects from the UV- radiation to the underlying tissues.
· Skin derivatives: Hairs, Claws, Cutaneous glands
· Develop from the epidermal cells.
1. Hair:
· It forms the exoskeleton of the body.
· Present all over the body except glans penis, teats, undersurface of the prepuce, clitoris, labia majora or minora, the inner surface of pinna.
· Hairs are the threadlike, cylindrical outgrowth of the epidermis which lie at the pit of the skin called a hair follicle.
· It is tubular outgrowth or invagination of the malpighian layer.
· It consists of root and shaft.
· The base of the follicle is evaginated from the hair papilla.
· The movement of the hair is controlled by erector pili muscles: its contraction raises hair.
· It is mesodermal in origin.
· It is composed of fibrous connective tissue, smooth muscle fibres, blood vessels, nerve fibres, adipocytes.
· Various sensory endings, hair follicles, sweat glands, sebaceous glands are present in the dermis.
· Pigment cells present in the outer layer of the dermis contain melanin which protects from the UV- radiation to the underlying tissues.
· Skin derivatives: Hairs, Claws, Cutaneous glands
· Develop from the epidermal cells.
1. Hair:
· It forms the exoskeleton of the body.
· Present all over the body except glans penis, teats, undersurface of the prepuce, clitoris, labia majora or minora, the inner surface of pinna.
· Hairs are the threadlike, cylindrical outgrowth of the epidermis which lie at the pit of the skin called a hair follicle.
· It is tubular outgrowth or invagination of the malpighian layer.
· It consists of root and shaft.
· The base of the follicle is evaginated from the hair papilla.
· The movement of the hair is controlled by erector pili muscles: its contraction raises hair.
2. Epidermal glands:
· They are present in the dermis but ectodermal in origin.
a. Sweat glands or sudorific glands:
· It is thin, long tubular glands. So, it is a simple coiled tubular gland.
· It is confined to the areas around the lips
· It helps in perspiration and temperature regulation.
· Mostly merocrine but those present in the axillary regions are apocrine.
· Sweat is a secretion as well as excretion.
· Note: sweat gland is absent in the skin of rats.
a. Sweat glands or sudorific glands:
· It is thin, long tubular glands. So, it is a simple coiled tubular gland.
· It is confined to the areas around the lips
· It helps in perspiration and temperature regulation.
· Mostly merocrine but those present in the axillary regions are apocrine.
· Sweat is a secretion as well as excretion.
· Note: sweat gland is absent in the skin of rats.
3. Sebaceous glands:
· It is alveolar glands and holocrine gland
· It secretes oily secretion called sebum which makes hairs greasy, slippery, soften the skin & waterproof to some degree.
· It opens into the neck of hair follicles
· It is alveolar glands and holocrine gland
· It secretes oily secretion called sebum which makes hairs greasy, slippery, soften the skin & waterproof to some degree.
· It opens into the neck of hair follicles
Other Modified Cutaneous glands:
1. Mammary glands
· They are modified sweat glands.
· It secretes milk and apocrine in nature.
1. Mammary glands
· They are modified sweat glands.
· It secretes milk and apocrine in nature.
2. Perineal or Inguinal gland or Scent gland
· It is associated with the reproductive organs of mammals and lies near the anus.
· It is a modified sweat gland.
· Its secretion has a pungent smell that gives the characteristic odour of rabbit.
3. Ceremonious or Wax gland
· It is present in the inner wall of the external auditory canal or meatus
· It is a modified sweat gland.
· Its secretion trap the dust particles to prevent them from entering into the eardrum.
· It is present in the inner wall of the external auditory canal or meatus
· It is a modified sweat gland.
· Its secretion trap the dust particles to prevent them from entering into the eardrum.
4. Lachrymal gland or Tear gland
· It is present under the upper eyelids towards its outer corner
· It secretes tear to keep the eye (conjunctiva) moist, soft, clear and free from bacteria or acts as antiseptic)
5. Meibomian gland
· It is a modified sebaceous gland.
· It is found in the dermis of the eyelid near its edge and opens into the follicles of eyelashes.
· It lubricates eyelid and cornea.
6. Zeis gland
· It is modified sebaceous gland
· It is present in the dermis of the eyelid but opens into the hair follicle of the eyelashes
· It keeps eyelashes smooth and soft.
7. Rectal gland
· It is a modified sebaceous gland.
· It is present near the rectum.
· Its secretion gives characteristics of smell.
8. Gland of moll (Tarsal gland)
9. Mammary glands
· These are modified sebaceous glands that produce milk.
· They are compound branched tubular glands.
· Their ducts are opened into the small projections of skin called nipples or teats as 4-5 pairs female. But in males they are vestigial.
· Their ducts are opened into the small projections of skin called nipples or teats as 4-5 pairs female. But in males they are vestigial.
Receptor present in the Skin:
1. Tango receptors or mechanoreceptors:
· It detects touch, pain and pressure.
· Examples:
a. Meissner’s corpuscles
· It is present in the dermis of the skin of fingertip or nipples or lips.
b. Pacinian corpuscles
· It is present in the subcutaneous tissue of the palm, soles to detect pressure.
c. Grandry’s corpuscles:
· It is present in the beak of birds.
d. Tactile receptor: It lies on the face of a mammal.
2. Nocireceptor- It detects pain.
3. Proprioreceptor- It detects the position of the body.
4. Thermoreceptors- It detects cold or heat.
Examples:
a. End bulb of Krause or frigidoreceptors: It detects cold.
b. Organ of Ruffini: It detects the heat
c. Ampulla of Lorenzini: It is found in fishes or sharks.
d. Ampulla of Lorenzini: It is found in fishes (Scoliodon)
a. End bulb of Krause or frigidoreceptors: It detects cold.
b. Organ of Ruffini: It detects the heat
c. Ampulla of Lorenzini: It is found in fishes or sharks.
d. Ampulla of Lorenzini: It is found in fishes (Scoliodon)
5. Rheoreceptors: It detects water current.
Example:
a. Lateral line system of fishes and tadpoles.
Example:
a. Lateral line system of fishes and tadpoles.
6. Photoreceptors- It is present in the retina of the eye to detect light.
Also, Read our Other Notes Related to RABBIT:
- External Features & Skin
- Digestive System & Digestion
- Respiratory System
- Circulatory System
- Lymphatic System
- Excretory System
- Reproductive System
- Nervous System
- Bones