The Tokay, Gekko gecko (Linnaeus, 1758). The first six photos on this page are captive animals, and an egg laid in captivity. These lizards are popular in the pet trade, and breed easily in captivity. Adults reach 350 mm in total length. While it can be found in forests, it is a human commensal, and uses buildings probably more often than it uses natural habitats. Bottom photo: Gekko gecko is commonly used in Chinese traditional medicine. This dried and stretched G. gecko was in a Kota Kinabalu (Sabah, Malaysia) market.

Many people living in Southeast Asia consider the Tokay (Gekko gecko) a symbol of good luck, seeing or hearing this common lizard increase’s ones chances of good fortune. The tokay was the first gecko described to science by Linnaeus in 1758, and it continues to provide science with interesting problems and has played a role in recent technology.

The frequency of sounds made by the tokay change with the time of day and the season.  Lowering light and ambient temperature increased the vocal activity, and vocalization also increases in late spring as androgen hormone levels increase and mass of gonads increased. All of this suggests the vocalizations play a role in courtship, territorial defense, and challenging predators.

In 2000, Robert Full et. al. (UC at Berkeley) discovered that tokays have about  a billion microscopic bristles on their toes that allow the lizard to use intermolecular forces, like van der Waals forces, to cling to surfaces. This has provided engineers with the idea for a novel synthetic adhesive that is dry and self-cleaning.

Tokays range from northeast India eastward throughout tropical Asia to the Indo-Australian Archipelago and the Philippines. They have been introduced to many places outside their natural range by man, including Martinique, Belize, Hawaii, and Florida. An acquaintance once brought me a tokay killed on the road in an area surrounded by corn fields in northern Illinois. Thus, it seems that this lizard has the opportunity to move into many new ecosystems and new geographic areas with the help of humans.

Trees and rock cliffs provide vertical surfaces for Gekko gecko to live their lives opposing gravity head down or upside down. Humans have increased the number of vertical surfaces available to these lizards with rock walls and buildings. Foraging for food, mating, and egg laying all occur on vertical surfaces for tokays.

Females lay clutches of two eggs with soft shells, these eggs are glued to a vertical surface in a location with a good food supply. The eggs may be attended by both sexes, and the incubation time ranges from 65-200 days (probably temperature dependent). Hatchlings are 50-75 mm. They reach sexual maturity in about 12 months. The life span in the wild is unknown, but captives have lived for 23 years.

Tokays are one of the largest geckos, males can reach a total length in the 300-400 mm range and females are 200-280 mm. Their large size, sharp teeth, and skillful hunting techniques makes them excellent predators on large insects, and since they are often found around human habitations, this means they feed on what most people consider insect pests. A recent study of foraging behavior in a Thai population reported that they emerged to hunt between 1800 and 2000 hours, and retreated to hiding locations between 0400 and 0700 hours. Their diet included insects of the orders Lepidoptera, Orthoptera, and Coleoptera. Prey size taken by males, females, and juveniles were not significantly different, suggesting that there was no selection for prey size.
There are about 10 species in the genus Gekko. How the tokay is related to these is unclear. Molecular studies have suggested it is related to the other species, but the genetic distances are significant.

Tokays are used in traditional Chinese medicines, and are collected for the pet trade. There is no evidence that they are endangered, in fact to the contrary they are very successful living with humans.