| HEARING SIGHT
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.
literature cited (,2,4,5,6,7,9)
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
LINKS PAGE - interesting sites to hear this)
"hooting" during the pre-mating rituals.
literature cited (2,4,5,6,7,8,9,11)
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
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
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.
As was mentioned above, chameleons have
a very limited sense of 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.
literature cited (2,4,5,6,7,9)
A chameleons tail is descried as
PREHENSILE, or adapted for gripping or climbing, and that it is. it is
almost like a fifth arm/leg, extremely strong, and generally longer than
the head and body. The only drawback is it is not regenerative as with
the anoles or
Another amazing feature of
chameleons is their feet, described as forceps like they have five toes
on each foot, fused together in opposing groups of two and three forming
pincers. They have three toes inward on the front feet and two toes
inward on the rear (known as ZYGODACTYLOUS). These feet
have sharp claws and extremely strong grips.
Experts consider the areas most
sensitive to touch to be the corners of the mouth, along the spinal
column, and the tip of the tail.
literature cited (2,4,5,6,7,9)
not really a "sense" but requires use of
Pacing or scratching at the
front of a cage by the chameleon is... they are asking to
get out. They are uncomfortable for some reason (lighting, temperature,
humidity)... maybe they just want to go on a "walkabout". You
should let them out and check those conditions important to them. If it
is an all glass enclosure this could also be related to a lack of good
air circulation. Another drawback to glass cages is chameleons do
not understand reflections and stress easily when they see their
own and perceive it as "another chameleon" ( talk about
being afraid of your own shadow ).
is used to
claim territory. If the cham sees another cham in the area they may
start bobbing their head. This is also practiced before mating. The
colors are a good indicator of reason, vivid colors are shown if it is
being done as a part of mating.
Gaping mouth with dark colors
and hissing... beware of "watchcham" they're
angry about something.
with pale colors is a sign of over heating. coo the cage and cham
with a good misting and adjust lighting if necessary.
Closing the eyes
long periods of time during the day... SIGN OF ILLNESS. Get
this cham checked out by a good herp vet before it is too late.
See ARAV Website if you don't know