Chamaeleontidae


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Chamaeleontidae

[kə‚mēl·ē′än·tə‚dē]
(vertebrate zoology)
The chameleons, a family of reptiles in the suborder Sauria.

Chamaeleontidae

 

a family of reptiles of the order Sauria. Chameleons may reach a length of 60 cm. The body is markedly compressed laterally, and the neck is short. In most species the tail is long and prehensile and can twist spirally; the only genera with a short tail are Brookesia and Rhampholeon. The back of the head is raised and has crests. In a number of species, mainly in the males, there is a protruding cutaneous process on the snout that is covered with scales, for example, in Chamaeleo nasutus and C. boettgeri. Some species, such as C. bifidus and C. ficheri, have two long, laterally compressed bony shields covered with scaly plates. Sometimes there are smooth or annular projecting horns; C. oweni has three such horns, and C. quadricornis has four. In some chameleons the back of the head has cutaneous lobes that bulge when stimulated.

The legs are long and slender, with five digits. Each group of two or three digits is enclosed in a cutaneous covering that extends up to the penultimate phalanx; the groups of digits are opposed to one another, so that the extremities resemble pincers. On the forelegs, three digits face in and two face out, while on the hind legs this arrangement is reversed. The body is covered with granular scales and bumps. The tympanic membrane is absent. The eyes are large, with heavy, fused lids and a small central opening for the pupil. The eyes move independently of one another.

The tongue is very long, often exceeding half of the length of the body without the tail. When at rest it is highly constricted. However, when the extensor muscles of the tongue are contracted and a number of others are simultaneously relaxed, it shoots forward with lightning speed. The teeth are acrodont. There are no clavicles. The animals have ventral ribs. In the majority of chameleons, except the genus Microsaura, the lungs have blind pouches that enable the lungs to inflate to a great size.

Chameleons are capable of rapidly changing their body coloration and markings in response to light and temperature changes and other stimuli. The color changes are explained by the presence of special chromatophores, which are regulated by the sympathetic nervous system. The dark brown, reddish, and yellow pigments in the chromatophores can redistribute themselves by gathering into compact granules or by dispersing, causing the color changes.

The family includes four genera, embracing approximately 90 species. The animals are distributed mainly in Africa and on the island of Madagascar and neighboring islands. They are also found in southern Europe and western and southern Asia. The majority live in trees and bushes.

Chameleons sit immobile for hours at a time, holding on to a branch with their extremities and tail. Only occasionally do they thrust out their tongues to capture their prey. C. chamaeleon is found in vegetation-poor areas, living in burrows. Representatives of the genus Brookesia sometimes live in dry foliage and feed mainly on various insects. Large chameleons sometimes also eat small vertebrates. The majority lay eggs—as many as 35 at a time. Some, for example, species of the genus Microsaura, are viviparous and bear as many as 14 young.

REFERENCES

Zhizn’ zhivotnykh, vol. 4, part 2. Moscow, 1969.
Fitzsimons, V. F. The Lizards of South Africa. Johannesburg, 1943. (Transvaal Museum Memoir, no. 1.)
Das Tierreich, Lfg. 83Liste der Rezenten Amphibien und Reptilien: Chamaeleonidae. Berlin, 1966.

I. S. DAREVSKII

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