Chamowners Web Likkin 1

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SMELL TOUCH COMMUNICATION WEIGHTLIFTING

Chameleons prefer to LICK the dew off of leaves over drinking still water. They have been known to lick the branches, or to be more accurate, taste test the branch with their tongue to determine if the territory is occupied. A male chameleon will rub its cloaca (vent) on branches after defecating, it is thought to mark their territory. This "taste test" or smelling of the branch is a substitution for their inability to smell. Their Jacobson's organ, located in the mouth of most reptiles, (used to "smell" particles picked up by the tongue) is virtually non-functioning, however, taste buds have been found in their tongues. Very little research has been done on this because it is considered to be an unimportant issue. I think there must be something important about taste to the chameleons. They tend to reject the same foods after a while, and seem to get excited about others.

See Myths -Tongue

literature cited (2,4,5,6,7,9)

HEARING

Chameleons have very limited hearing, tuning in to frequencies between 200 and 600 Hz as compared to most other lizards from 100 to 4000 Hz, and to humans 20 to 20,000 Hz. Most snakes can pick up sound waves between 100 to 700 Hz.

Chameleons ears have degenerated over time, are covered with scales, and possess no eardrums.

Female C. Oweni, and C. Johnstoni are known to produce low purring sounds when being handled by humans or approached by males of their species. Male veiled chameleons have been recorded (see LINKS PAGE - interesting sites to hear this) "hooting" during the pre-mating rituals.

literature cited (2,4,5,6,7,8,9,11)

SIGHT

Chameleons have one of the most sophisticated eyes in the animal kingdom. They are described as binocular (each eye moves independently of the other) and are probably the chameleon's greatest sense. Combined they provide nearly 360 degree vision without turning the head, and allow the chameleon to see in front of and behind him

When searching for prey, the eyes are constantly moving in independent directions. when the meal is spotted BOTH eyes lock on the target and the tongue ZAPS it (see TONGUE on MYTHS PAGE). When the tongue is released, the eyes are closed for protection from projectile damage. More protection for these irreplaceable assets is exercised when the animal sleeps. Their eyelids close, and the eye rolls down until the pupil is behind a protective bone. Still even more insurance against damage comes in the form of scale covered eye lids. They completely cover the entire eye except for a small opening for the pupil.

The first time a chameleon is observed cleaning its eye can cause great stress to the chameleon owner. It appears that their eye is about to pop out of the socket. They will "blow up" their eye turret and rub it on something to clean it or to knock off loose skin during shedding.

NEGATIVELY POWERED LENS IN THE CHAMELEON'S EYES

According to a paper published in the 23 February 1995 issue of Nature, research done by Matthias Ott and Frank Schaeffel of the University Eye Hospital, Department of Experimental Ophthalmology in Tubingen, Germany has shown that chameleon's eyes have a negatively powered lens. This negatively powered lens gives the chameleon a fast-focus telephoto eye that can judge distance much like a reflex camera, unlike other vertebrates whose eyes must triangulate on an object using binocular vision to get a distance bearing. In the paper, Ott and Schaeffel also show that the image that forms on the retina of the chameleon is 15% larger than it would be for other vertebrates. The following is the introduction of the published paper.

Chameleons are arboreal lizards that spot their prey visually and catch it by highly precise shots with their long sticky tongue. They scan their environment by large-amplitude independent saccadic eye movements; once an insect is detected, the head axis is aligned towards the target (head tracking), both eyes come forward to fixate the insect and, in a phase called 'initial protrusion', the sticky tongue is loaded with tension by a special hyoid apparatus and subsequently shot out of the mouth with great precision. Lenses placed in front of the eyes produce predictable errors in distance estimation, suggesting that chameleons rely on accommodation cues when measuring the distance to their prey, but focusing has never been measured directly. Using a new technique to measure accommodation, we now show that accommodation is precise enough to serve as the major distance cue. Because accurate focusing requires large retinal images, we have tested image magnification and found that it is higher than in any other vertebrate eye scaled to the same size. This is a result of a unique optical design: unlike other vertebrate eyes, the crystalline lens of the chameleon has negative refractive power. Although there is a trend among vertebrates to increase corneal power and to decrease lens power with higher visual acuity, only in the chameleon eye has this tendency led to a reversal of the sign of the power of the lens.

literature cited (2,4,5,6,7,9,11,12)