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Lab.17
Rabbit
practical biology
* External features for rabbit:
1- Note that there is an almost complete covering of hairs on the outer surface of the
body.
2- Divisions of the body are the head, neck, trunk, with two pairs of limbs, and tail.
3- In the head, note the anterior mouth bounded by two mobile lips (characteristic of
mammals); the upper lips is divided by a median cleft which connects the mouth
with the external nostrils which are lie on the tip of a mobile nose (characteristic of
mammals). Two large eyes, each guarded by two eyelids, an upper and a lower
fringed by eyelashes, and a third or nictitating membranes attached to the anterior
angle of the eye. On the anterior of facial region of the head are a few tactile hairs,
the vibrissae, which are greatly enlarged. The pinnae are parts of the external ears,
and are freely movable (mammalian feature).
4- On the two sides of the urinogenital aperture in both sexes are two hairs less
inguinal depressions on to which open the ducts of perineal glands (scent glands).
They secrete a substance which gives the rabbit it is characteristic odour by means
of which it can distinguish it is own kind by smell.
5- A long the ventral surface of the thorax and abdomen are 4-5 pairs of teats on the
tips of which open the ducts of mammary glands in the female.
6- The limbs are built up on the same plan as in the other tetrapods, the hand has 5,
and the foot only 4 digits which terminate in strong curved claws. Note that the
hind limbs are longer than the fore-limbs (adaptation of leaping).
* Digestive system:
1- Mouth cavity: is containing on teeth and internal nares which lies above a beyond
the soft palate. The tongue is an elongated movable muscular mass, free in front
and attached behind to the floor of the mouth by the frenulum linguae.
2- The esophagus, which extend in the neck region dorsal to the trachea and passes
backwards into thoracic cavity and pierces the diaphragm and open into the
stomach.
3- The stomach (a large sac) is consisting of wider portion, cardiac region and pyloric
portion.
4- The small intestine follows from the pyloric portion of the stomach. The
duodenum (U-shape), then jejunum, and ileum.
5- The large intestine consists of caecum, colon, and rectum. The cecum ends by
vermiform appendix. The rectum is end by anus.
6- The pancreas is lie between the two limbs of the duodenal loop.
7- The liver is very large, dark red in color. It is consist of 5 lobes. The right and left
central, the left lateral, the caudate, and the small spigelian lobes. The right central
lobe is grooved for the reception of the gall-bladder.
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* The respiratory system: consists of:
1- External nostrils which are lie on the tip of a mobile nose, and nasal passages.
2- The larynx: box-like structure, and opening into the pharynx by the glottis and
epiglottis.
3- The trachea: This is recognized by its cartilaginous incomplete rings.
4- Two bronchi each passes into a lung. Note that the right lung is formed of 4, the
left of 2 lobes.
5- The muscular diaphragm which plays an important role in breathing.
* Skeletal system:
1- The skull
2- The vertebral column: is divided into (cervical, thoracic, lumber, sacral, and caudal
vertebrae.
3- The ribs and sternum.
4- The pectoral consists of scapula (triangular plate), clavicle and coracoid bones.
5- The for-limb is consist of humerus, radius & ulna, carpus (9 pieces), metacarpus (5
metacarpalia)
6- The pelvic girdle is consisting of antero-dorsal large ilium, postero-dorsal ischium,
and ventral small pubis.
7- The hind-limb is consisting of femur, tibia & fibula, tarsus (6 pieces), metatarsus
(4 metatarsalia).
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