Gecko - biology.

Gecko - biology. Gecko, common name for members of a family of small, harmless lizards, found mainly in tropical regions. Certain species of this family make a loud clicking noise that sounds like "gecko"; they are the only lizards that make any sound other than hissing. Geckos are often seen at night running upside down on the ceilings of houses. Some geckos have a disk on each of their toes composed of scales with many minute brushlike projections. The special size and shape of the projections allow these geckos to cling to and move across smooth surfaces using van der Waals forces (see Johannes Diderik van der Waals; Molecule). Geckos vary in body length from 1.5 to 25 cm (0.5 to 10 in) and often have broad, flattened heads and thick, stumpy tails. The skin is often coated with tiny, beadlike scales. In most species the two eyes are each covered by a transparent membrane kept clean by the tongue, which is thick and sticky. Most geckos feed at night on insects and are attracted to common household pests. Females usually lay two white, hard-shelled eggs. Most geckos are tan, brown, or grayish; exceptions include the day geckos of Madagascar and other parts of Africa, which are bright green with spots of orange or yellow, and the tree geckos of New Zealand, which are green or yellowish with pale markings. Geckos are not venomous, although in some regions they are feared as poison lizards. The banded gecko is the most widespread North American species. The Eurasian Mediterranean gecko is known to be a stowaway on ships and trucks; it has been widely introduced in tropical and subtropical regions, including the southern United States. The tokay of Southeast Asia, a large gecko with three different loud calls, is often sold as a pet, although it has an unpleasant temperament and is capable of delivering a severe bite. Scientific classification: Geckos make up the family Gekkonidae. The African day gecko is classified in the genus Phelsuma, and the New Zealand tree gecko in the genus Naultinus. The banded gecko is classified as Coleonyx variegatus, the Mediterranean gecko as Hemidactylus turcicurus, and the tokay gecko as Gekko gecko. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.