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Chameleon forest dragon (Gonocephalus chamaeleontinus)

Bunglon hutan or chameleon anglehead lizard or chameleon forest dragon (Gonocephalus chamaeleontinus) is an animal species in Agamidae, having a larger size than other species, the most unique head shape and has the ability to change color by changing mood rather than for camouflage.

Morphology

G. chamaeleontinus has a total length of 40 cm, the muzzle to the buttocks is 16 cm, the base color is green with orange, yellow to brownish spots and sexual dimorphism. The eyes are protected by a movable eyelid surrounded by a slightly darker color, while males have a bright blue color around the eyes.

Dlium Chameleon forest dragon (Gonocephalus chamaeleontinus)

Short head with a triangle and thorns above the eyes. Medium-sized head scales, vary, smooth and have a little tubercle that extends above the ear. Heterodont teeth with acrodont type and dorsal tongue are covered by reticular papillae.

The upper labial scale consists of 10-12 units and the lower labial scale consists of 11-14 units. Dorsal body scales are composed of small and fine scales with a few widening in all directions, ventral scales are larger when compared to dorsal, smooth and become differentiated with other species.

Wide gular pockets covered by small, fine scales and jagged anterior ends. Having an outer ear hole, the tympanum membrane looks conspicuous by the size of half of the diameter of the eye when it opens.

The snout from the rostral to the nose is the same length as the diameter of the eye, females usually have a slightly rounded snout. The supraciliary border rises posteriorly and is stiff. Canthus rostralis protrudes and extends from nostril to the top of the eye.



Slim body, nuchal crest and dorsal crest connect, starting in line with the posterior border of the eye. Nuchal crest is very high or almost equal to the length of the snout, composed of flat and long scales with a bottom consisting of three rows of smaller scales.

Nuchal crest in males develops better than females. The nuchal crest starts from the occipital part, while the dorsal crest starts from the end of the nuchal crest to the tail. The dorsal crest is much shorter than the nuchal crest because it is reduced to a bulge posteriorly.

Flat tails up to 25 cm long, serrated at the top end and covered with large scales that are smooth and budded with a larger size in the inferior part. The tail has a function as a stabilizer when moving in trees, the color patterns of dark and light rings. Cannot regenerate a tail that has broken off like some other lizards.

Chameleon forest dragon has four extremities, a pair of legs on the anterior and the other pair on the posterior near the cloaca. The legs have a relatively long and slender size. The posterior limb is longer than the anterior. The scales on the limbs are slightly different, smooth or slightly off.

Each leg has five fingers with sharp claws for semi-arboreal adaptation as a tool to grip tree bark and move easily to chase prey or escape from predators. Usually the fourth finger tends to be longer.

Sex dimorphism

Sex dimorphism can be seen from the color pattern where males usually have a brighter color with orange, yellow or brown spots while in females tend to have a green base and blackish spots. Basically the color pattern depends on the locality for example males on the island of Sumatra tend to be brownish overall.

A gular bag in which bright blue skin around the eyes is a sign of a male. Males also do not have the femoral gland to help mating and the dorsal crest develops better.

Behavior

Bunglon hutan live at an altitude of 500-700 m, but perhaps up to 1600 m, tropical rain forests that have open canopies, near rivers, enough sunlight with certain soil moisture and humidity.

Chameleon anglehead lizards tend to be diurnal, whereas at night they tend to be inactive and sleep in a vertical position in twigs of 20-60 mm diameter that are easily gripped by claws and make it easier to observe the surroundings in preparation for escaping if predators suddenly attack.

G. chamaeleontinus spends 50% of the time in the tree and always runs short distances to move, then stops and observes the surroundings, if the situation is safe will continue on the same steps repeatedly. Females spend 70% of their time on the ground, including laying eggs.

Males have a territory area of around 300x700 m and will fight by head banging and widening the gular sac to defend the area from other males. Females and juvenile males are free to enter the area of adult males anywhere.

Chameleon forest dragon is easily scared and stressed, especially meeting humans or predators that can be seen by changing colors from bright to dark. They will wriggle with all their might, bite and scratch anything to defend themselves.

Bunglon hutan hunt for prey using a sit and wait strategy. They observe prey at a height of 1.4 m, then drop down on prey and are carried up into the trees at a height of 1.6 m. Prey are generally moving and active including grasshoppers, cockroaches, grubs, worms, crickets, spiders, ants, beetles, butterflies, baby mice, snails and small lizards.

Reproduction

Females migrate to open vegetation and lots of sun to nest and hoard 5-8 eggs in November-December. The spawning period is around 36-53 days. The eggs are buried at a depth of 1-4 cm, 5-9 cm long and triangular in shape. The mother may make several experimental nests before finally making the actual nests.

The most ideal temperature for egg incubation is 21-24C and humidity 70-80%. Unstable temperatures result in incubation for up to 99-101 days. Babies like to die when touched, eyes closed, body curled and did not move. Juveniles 80-100 days old have preyed on crickets and small insects.

Chameleon anglehead lizard defend themselves from predators in various ways including escaping or camouflage with discoloration or counterattack by biting and clawing to escape.

This species identifies predators using a pair of eyes and a pinneal eye as a mechanoreceptor and thermosensor. This organ is located on the head of the parietal part. They also use tree trunks by turning to the other side to avoid predatory views.

Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Sauria
Family: Agamidae
Subfamily: Draconinae
Genus: Gonocephalus
Species: Gonocephalus chamaeleontinus

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