The leopard gecko (Eublepharis
macularius) is a member of Eublepharidae, a primitive gecko family that includes the fat tail gecko Hemitheconyx caudicinctus
from Africa, the genus Coelonyx from Southwestern USA and the cat gecko Aeluroscalabotes felinus from Southeast Asia. They
share similar features that differentiate them from typical geckos. Firstly they lack specialized toe pads as in typical geckos,
therefore they cannot climb smooth vertical surfaces such as walls, although they can climb rough surfaces to some extent.
Secondly they have movable eyelids which the typical gecko does not have. However, they have one common characteristic of
geckos, the ability to break their tails off. This is called autotomy, and is a defense mechanism used when confronted by
predators in the wild. The tail is annulated, meaning the sections are segmented and are able to break off at any point along
the tail length. Upon breaking, the specialized blood vessels immediately seal up, so very little bleeding is seen. At this
time, the gecko will have to eat plenty of food to regain the lost stored energy in the tail. After a few weeks, a new tail
will grow back but the shape will be different from that of the original tail (Bartlett and Bartlett, 1999).
Leopard geckos are native to Pakistan and India, where they live in the desert grasslands that resemble the
hot and dry conditions of savannahs. During the day they hide in empty burrows dug by rodents and other creatures, and under
rocks or bushes, only coming out at night to hunt for prey such as crickets and grasshoppers (Nickerson, 1997-2006). The average
length of a fully grown leopard gecko is approximately 7 to 10 inches. The males are bigger than the females and have a heavier
built. In addition, they have large femoral pores and hemipenal bulges on their tail bases. Babies are banded without spots.
As they grow older, the bands disperse and depending on the type of morph/patterning, the amount of spots will gradually appear
until they reach adult stage (Bartlett and Bartlett, 1999).
Vision and hearing
The vision of a leopard gecko
is a complex combination of biological components. Basically a leopard gecko eye, like that of other nocturnal reptiles, has
a large pupil and cornea. By the help of ciliary and annular muscles, the pupil can contract and expand in respond to different
light levels. In addition, geckos share a common trait with other reptiles in that their retinas contain photoreceptors that
are able to detect different wavelengths, including that of UV, so allowing them to have a colour vision (Kaplan, 2003).
in reptiles has been and still in research. Different reptiles show varying degrees of being able to detect sounds and vibrations.
Many have a typical tympanic membrane which in geckos, for example, is located deep in the head. The function is simple, when
sound reaches the membrane, it causes certain vibrations which are transferred by the interconnecting muscles called stapes
which then transfer the vibrations to the inner ear cavity which includes the fluid-filled cochlear duct and then to the sensory
clusters which then passes the impulse to the brain along the auditory nerve (Kaplan, 2003).
Their hunting methods are interesting to observe. The gecko first watches
from a distance as the prey crosses its vision. When it has a clear focus on the target, it advances slowly, like a cat, lifting
one leg and holding its posture still before carefully stepping forward. At the same time, its tail waves slowly from left
to right like a flag (Bartlett and Bartlett, 1999). When it is within reach, excitation from the impulse in the central nervous
system produces involuntary movement of the tail muscles, so that the tail vibrates before the gecko lunges forward. It may
take only a split second but sometimes it may miss the prey item. Body language plays an important role in breeding behaviour
as well. In breeding females, the tail is held high up and moved from side to side to indicate receptiveness in mating. Males
display a waggling of only the tail tip as a sign of being interested to mate with the females (Smith, 2004).
Vocalization is also an important part of leopard
gecko behaviour. A hatchling or juvenile, when threatened will emit a screeching sound, which some owners compare to a boiling
kettle which will scare off the potential enemy. Adults, if handled roughly, will make low squeaks, like a door creaking.
Clicking, chirping and squeaking sounds are normally made in territory fights (Smith, 2004). However to the observations made
by different leopard gecko keepers, these sounds are only made by some, not all, leopard geckos.
Another unique nature of leopard gecko morphology is that
the sex is determined by the temperature at which the eggs are kept during the incubation period rather than genetically.
This is because certain species of reptiles like the leopard gecko do not have the normal X and Y chromosomes that determine
sex in most animals (Crews, 2003). The parameters are as follows:
1. At temperature ranges of between
28.9 oC and 30.6 oC, both sexes will be produced (Bartlett and Bartlett, 1999).
2. At temperatures
below 28.3oC, high proportion of females to males will be produced (Bartlett and Bartlett, 1999).
At temperatures above 31oC, high proportion of males to females will be produced (Bartlett and Bartlett, 1999).
if the eggs are incubated at temperatures above 32 oC, females are again produced. These are called superfemales, because
they are large and highly aggressive, and act like males, therefore are unsuitable for future breeding (Crews, 2003).
Leopard geckos as pets
Due to their docile, calm behaviour, leopard geckos
are a favourite beginner lizard for those new in keeping reptiles. It is not until the mid 90s that serious breeders from
around the world began importing wild specimens from Pakistan and India (Nickerson, 1997-2006) and currently there are more
than twelve morphs in the exotic pet market of countries such as the UK, North America, and Canada. The oldest morphs initially
appeared around 1994 where high yellow and jungle leopard geckos were produced from wild stock. Selective breeding for size
and carefully planned genetics were implemented until in 1997 the first albino geckos came into the market, and several years
later saw newer morphs such as blizzards, leucistic, tangerine and their sub morphs, as well as one of the latest 2004 morphs,
the Mack Snow. It is very interesting to anticipate a new morph from a batch of hatchlings because they are rare and randomly
produced with each clutch.
Due to the sensitive nature of leopard geckos, like other reptiles, one must ensure the gecko does not struggle or placed
in an uncomfortable position while being handled. If it does, chances are that the gecko may regard the handler as a threat
and may by instinct drop its tail to escape. Hatchling and juvenile leopard geckos are more skittish and do not respond well
to handling. While this may seem frustrating to the owner, according to many herpetologists, being fast moving and elusive
is Natures way of ensuring survival. In addition, potential predators are viewed as attacking from above, like birds and larger
animals therefore, approaching it and grasping it from above will result in an unhappy, wriggling gecko (Bartlett and Bartlett,
In breeding projects, temperature is also the main cause of other abnormal occurrences that affect leopard gecko
development during incubation aside from being a sex determinant. Inappropriate incubation temperatures cause deformities
in body structure such as missing or twisted limbs, missing tail segments, runts, kinked tails, and other extreme conditions.
Genetic defects may also play a factor, although it is minor and thus sometimes negligible.
However slow it may seem,
the rest of the world is already beginning to catch up on keeping these beautiful reptilian masterpieces as living collections
and running their own breeding projects. Therefore, in view of the increasing number of potential keepers and breeders it
is important for leopard geckos to be understood as much as possible in terms of behaviour and husbandry so they can be truly
appreciated and receive proper respect and treatment in captivity.
Bartlett, R.D.; Bartlett, P. (1999) Reptile Keepers Guides Leopard and Fat
Tailed Geckos Barrons Publishing, New York, U.S.A.
Crews, D. (2003) Sex determination Where environment and genetics
meet, Evolution and Development; Vol. 5; Iss.1, pg.50 -55.
Kaplan, M. (2003) Reptile Hearing,
http://www.anapsid.org/reptilehearing.htmldate accessed: 1/7/06.
Nickerson, C. (1997-2006) Leopard Geckos,
http://members.aol.com/msnick1/leopardgeckos.htmldate accessed: 1/7/06.
Smith, P. (2004) Leopard Gecko Behaviour
http://www.thegeckospot.com/leocareindex3.htmldate accessed: 30/6/06.