Travel Reference
In-Depth Information
Chameleons use body language more than colour to deter enemies. If you spot a
chameleon on a branch you will note that his first reaction to being seen is to put the
branch between you and him and flatten his body laterally so that he is barely visible.
If you try to catch him, he will blow himself up, expand his throat, raise his helmet
(if he has one) and hiss. His next action will be to bite, jump, or try to run away. For-
tunately they must be the slowest of all lizards, are easily caught, and pose for the
camerawithgloomyresignation(whocanresistananimalthathasaconstantlydown-
turned mouth like a Victorian headmistress?). This slowness is another aspect of the
chameleon's defence: when he walks, he moves like a leaf in the wind. This is fine
when the danger is an animal predator, but less effective when it is a car. In a tree, his
best protection is to keep completely still. He can do this by having feet shaped like
pliers and a prehensile tail so he can effortlessly grasp a branch, and eyes shaped like
gun-turrets which can swivel 180 degrees independently of each other, enabling him
to view the world from front and back without moving his head. This is the chamele-
on's true camouflage.
The family Chamaeleonidae is represented by three genera, the true chameleons -
Calumma
and
Furcifer
-andthelittlestump-tailedchameleons,
Brookesia
.Unlikethe
true chameleons, the
Brookesia
's short tail is not prehensile.
In chameleons there is often a striking colour difference between males and fe-
males. Many males have horns (occasionally used for fighting) or other nasal pro-
tuberances. Where the two sexes look the same you can recognise the male by the
bulge of the scrotal sac beneath the tail, and a spur on the hind feet.
It is interesting to know how the chameleon achieves its colour change. It has a
transparent epidermis, then three layers of cells - the top ones are yellow and red, the
middle layer reflects blue light, and the bottom layer consists of black pigment cells
with tentacles or fingers that can protrude up through the other layers. The cells are
under control of the autonomic nervous system, expanding and contracting according
to a range of stimuli. Change of colour occurs when one layer is more stimulated than
others, and patterning when one group of cells receives maximum stimulation.
In the early 17th century there was the firm conviction that chameleons subsisted
without food. A German author, describing Madagascar in 1609, mentions the
chameleon living 'entirely on air and dew' and Shakespeare refers several times to
thechameleon'ssupposeddiet:'Thechameleon...canfeedonair'(Two
Gentlemenof
Verona
)and'ofthechameleon'sdish:Ieattheairpromise-crammed'(
Hamlet
).Poss-
iblyatthattimeno-onehadwitnessedthetongueflashoutthroughthebarsofitscage
to trap a passing insect. This tongue is as remarkable as any other feature of this ex-
traordinary reptile. It was formerly thought that the club-shaped tip was sticky, allow-
ing the chameleon to catch flies, but researchers discovered that captive chameleons
had been catching much larger prey -lizards, intended to coexist as cagemates. These
