In this article we will discuss about the external structure of toad. This will also help you to draw the structure and diagram of toad.

Toad has a short bilaterally symmetrical body (Fig. 1.61). There is no exoskeleton over the skin, i.e., the skin is naked skin is rough in texture. The dorsal side of the body is blackish-gray while the ventral side is yellowish grey. Toad can change the colour of the body to match with the hues of its surroundings.

An adult toad in a sitting posture

Ordinarily, its body colour is same as that of the earth. The body is divisible into head and trunk. Distinct neck is absent. A postanal tail is absent in adult stage. The tail is present and well-developed in the larval condition. The head is semicir­cular in outline. It is broad, depressed and has a blunt snout.

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Mouth is a wide opening located at the terminal end of the head. At the anterior dorsal side of the head there is a pair of rounded openings known as nostrils or external nares. The eyes are very large and prominent. Each eye is provided with a thick upper eyelid and an ill-developed lower eyelid.

A transparent nictitating membrane (or third eyelid) is present and it is stretched to cover the eye ball. Behind each eye, a circular area known as eardrum (or tympanum) is present. Just behind each tympanum there is an elongated elevation called parotid gland. These paired glands secrete a whitish, pungent, sticky poisonous juice.

These glands act as the organs of offense and defence. The skin on the floor of the buccal cavity becomes inflated to form vocal sac in males. The trunk is broad, short and flattened. Numerous small bumps known as warts are present on the dorsal side of the body. The cloacal aperture or vent is located on the dorsal side of the pos­terior end of the body between the two hind limbs.

There are two pairs of limbs. These are of unequal size. The forelimbs are smaller than the hind limbs. Each forelimb consists of brachium (upper arm), and ante-brachium (forearm), a wrist and a manus (hand). The hand is followed by four digits. In male individual, a cushion-like thumb pad (or nuptial pad) develops during breeding season at the basal part of inner finger. These pads fascilitate the males grip during copulation.

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The hind limbs are strongly built and are much longer than the forelimbs. These two limbs are modified for jumpi