Calotes Versicolor || External characters || Digestive system

External characters and digestive system of Calotes versicolor

A] External characters

    i] Shape, Size and Color :- 

        Body is elongated, slender, lizard-like & divisible into head, neck, trunk & tail. Male is brightly colored, golden yellow with a greenish tinge. Throat is pale red, often with a black transverse stripe. female is not so brightly colored. Male is larger and stronger than female, measuring about 35cm is length including tail.

    ii] Head :-

        The head is larger & somewhat pyramidal in shape with a short conical shout which bears a wide, slit-like aperture, the mouth running round the anterior border of the head & a pair of small external nares, pair of eyes with nictitating membrane.

    iii] Trunk :-

        Head is connected with the trunk with a short a neck. The trunk is elongated, strongly convex dorsally, laterally compressed & flattered ventrally. Each forelimb has an upper - arm or branchium, the forearm or antebranchium, the hand or manus & five horny clawed digits; while each hind limbs comprises the thigh or femur, Shank or crus, foot or pes & five clawed digits, of which the hallux or 1st is smallest.

    iv] Tail :-

        Tail is cylindrical, tapering showing alternate dark & light annuli & is nearly twice as long as the head & trunk together.

    v] Skin :-

        Skin is dry & devoid of glands. The body is completely covered with epidermal horny, imbricate and unequally shaped posteriorly directed scales which are periodically shed in tufts. Melanophores lie more superficially in the dermis and iridocytes and lipophores. It is able to change color.

    vi] Scales :-

        Scales from the continuous covering over the body of Garden Lizard(Calotes)., but become thinner in the grooves between the scales. Scales on the body of Calotes are of two types - large scales & small scales.

    vii] Claws :- 

        The tips of the digits of the Garden Lizard (Calotes) are provided with pointed claws.

B] Digestive system of Calotes versicolor 

        The digestive system of Calotes is made up of the alimentary canal and digestive glands.

    i] Alimentary canal :- 

        It is consist of mouth, oesophagus, stomach, intestine, cloaca. The alimentary canal starts from the mouth.

        The mouth is a transverse terminal opening provided with the jaws, the jaws are provided with the teeth. The teeth are sharp, small, pointed & recurved backwards. They are actually simple cones (haplodont) having an enamel cap & an interior ortho-dentine. The style of attachment of the teeth is identified as that of pleurodont, that is, the teeth are attached to the outer wall of the alveolar groove.

        The mouth leads into the buccal cavity which is large & compressed dorsoventrally. In the posterior part of the roof of the oral cavity, there are two openings for the internal nerves.

        The tongue is protrusible & the apex of the tongue is slightly bifurcated. The buccal cavity passed to the stomach through pharynx & oesophagus. The oesophagus is a smallest tube which transfers food from buccal cavity to the stomach. The abdomen is elongated, pouch-like and held more or less vertically. The stomach is divisible into a cardiac & pyloric portion. The pyloric part of the stomach is followed by small intestine which is narrow tubular & coiled. The small intestine may again be divided into a u-shaped duodenum & a long much coiled ileum. The small intestine is followed by a large intestine (or rectum) which is small, sac-like & opens into the cloaca. At the junction of ileum & rectum a small projection, called coeliac caeum, is present. the cloaca opens outwards from the anus.

    ii] Digestive glands

        Small unicellular salivary and mucous glands are present in the oral cavity. These glands are few in number. The liver secretes bile. The bile remains stored in the gall-bladder. Gallbladder is a small round sac that is the liver. Gallbladder acts as a storehouse of bile. The inner wall of the stomach is beset with a large number of unicellular parietal glands and gastric glands which secrete hydrochloric acid & digestive enzymes respectively.

    iii] Mechanism of food - getting and digestion

        Calotes' diet consists mainly of small live insects. Ingestion is done with the help of the tip of the tongue & the insect is taken inside alive. Viscous mucous secretion helps to capture prey.