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Marvellous feats of geckos 

Medical researchers are intrigued by how a gecko is able to grow a new tail without the fluid retention and swelling (lymphoedema) frequently associated with radical human surgery. The key seems to be a potent protein growth factor, discovered in geckos, which enables them to regenerate their lymphatic systems. It is hoped a similar product can be developed for humans.

Some geckos are able to perform gravity-defying feats, walking on ceilings and on panes of glass, thanks to numerous little hooked bristles on the soles of their feet which give them an astonishing grip. Scientists in California are hoping to produce synthetic versions which could be used to improve tyres and shoes for athletes — and perhaps make ceiling painting easier!

Documents

Tropical Topics, No.78, June 2003 - Lizards
The diverse lizards of Oz [pdf 1.4 Mb]


Geckos

From Tropical Topics newsletter, No. 78 June 2003, produced by Stella Martin at the Queensland Environmental Protection Agency. Download the PDF to read the whole issue. Acknowledgements to Russell Best, Queensland Parks and Wildlife Service and Tony Griffiths, Key Centre for Tropical Wildlife, Charles Darwin University.

Geckos in the tropics |  Family Gekkonidae | Diplodactylus genus | Spiny-tailed geckoBynoe’s gecko |

Geckos in the tropics

Knobtail Gecko
Knobtail gecko found in north east Queesland in the Charters Towers area. Photo: Leonie Valentine

Geckos are among the most familiar of tropical animals, living in our houses, scuttling around our ceilings, swarming around our outside lights to pounce on dazzled insects and conducting their affairs behind our picture frames. Several species of geckos qualify as ‘house’ geckos, having adopted humans as co-habiters. Gehyra dubia is found widely in Queensland and northern New South Wales. Varying in colour from pale pinkish to brown with darker markings, it can also be found in the wild on trees and in rock crevices.

Another species, Hemidactylus frenatus , is an import from Asia which has hitched a lift with travelling humans. It is now found at the tip of Cape York Peninsula, around Cairns and in the Northern Territory where it is spreading from Darwin to settlements along the road south towards Alice Springs. It seems to be dependent on human habitation. This gecko can change colour, becoming pale at night and dark during the day. Although similar in appearance to Gehyra dubia, it can be distinguished by its slightly spiny tail. It also has a distinctive loud scolding call; native house geckos make only a soft chattering call.

The nocturnal lifestyle of geckos prevents them from basking in the sun as most lizards do to raise their body temperatures. Instead, they choose daytime retreats which are warmed by the sun, particularly in the afternoon, so that they are full of energy by sunset. Competition for suitable spots can be fierce, leading to fights between opponents during which they grasp each others’ tails in their mouths.

Family Gekkonidae

There are more than 90 gecko species in Australia, most of them under 20 cm in total length. These are nocturnal lizards although they may be active in dark places during the day. They feed only on prey which moves, such as insects and smaller geckos. A gecko’s eyes are permanently covered with a transparent eyelid, perhaps to reduce evaporation. Unable to clean its eyes with tears, the gecko licks them with its tongue. Some gecko species are parthenogenic, meaning that the females can produce offspring without male input.

Diplodactylus genus

Over 30 of the gecko species found in Australia belong to the Diplodactylus genus. The fat-tailed diplodactylus (Diplodactylus conspicillatus) is found only on the ground in stony and grassy areas across much of the top of Australia, its colour varying to match the habitat in which it lives. About 10cm in total length, it has a bulbous tail which acts as a fat storage organ, and feeds on termites and other insects. The fat-tailed diplodactylus spends its days in underground holes, such as abandoned burrows of trap-door spiders, blocking the entrance with its fat tail to keep out predators and keep in moisture. It is sometimes called the burrow-plug gecko. Most adults have lost their original tails which are replaced with more rounded ones which make even better burrow-plugs.

Spiny-tailed gecko (Diplodactylus ciliaris)

The spiny-tailed gecko is found in woodlands and grasslands, westwards from western Queensland, living in trees or other vegetation. It is also frequently seen on roads. This is one of 10 ‘tail-squirting’ species. It can eject an offensive and sticky liquid from the spines of its tail. By lifting its tail it can aim the fluid accurately up to a distance of 30 cm. This gecko is also particularly good at changing colour from dark to very pale.

Bynoe’s gecko (Heteronotia binoei)

Bynoe's gecko is very common throughout most of the Australian mainland. Also known as the prickly gecko, because of its bumpy skin, it thrives in all types of habitat from forests and woodlands to arid areas. It shelters in crevices, under logs and in rocks, but at night searches open ground for insects — and other geckos. These geckos sometimes lay eggs in communal nests which may contain up to 150 eggs .