35-632: Gekkonidae (the common geckos ) is the largest family of geckos , containing over 950 described species in 62 genera . The Gekkonidae contain many of the most widespread gecko species, including house geckos ( Hemidactylus ), the tokay gecko ( Gekko ), day geckos ( Phelsuma ), the mourning gecko ( Lepidodactylus ), and dtellas ( Gehyra ). Gekkonid geckos occur globally and are particularly diverse in tropical areas. Many species of these geckos exhibit an adhering ability to surfaces through Van der Waals forces utilizing intermolecular forces between molecules of their setae (foot hair) and molecules of
70-421: A diameter of 5 μm . Human hair varies from 18 to 180 μm, so the cross-sectional area of a human hair is equivalent to 12 to 1300 setae. Each seta is in turn tipped with between 100 and 1,000 spatulae. Each spatula is 0.2 μm long (one five-millionth of a metre), or just below the wavelength of visible light. The setae of a typical mature 70- gram (2.5- ounce ) gecko would be capable of supporting
105-1184: A full list, see section 'Genera'. Gekkonidae contains these genera: Possibly belonging to the family: † Yantarogekko (fossil) Pyron, et al. (2013) presents the following classification of Gekkonidae genera, based on molecular phylogenetics . Lepidodactylus , Pseudogekko , Luperosaurus , Gekko , Dixonius , Heteronotia , Nactus , Hemiphyllodactylus , Gehyra Alsophylax , Tropiocolotes , Cnemaspis , Mediodactylus , Pseudoceramodactylus , Tropiocolotes , Stenodactylus , Bunopus , Crossobamon , Agamura , Cyrtopodion , Cyrtodactylus , Hemidactylus Perochirus , Urocotyledon , Ebenavia , Paroedura , Ailuronyx , Calodactylodes , Ptenopus , Narudasia , Cnemaspis , Uroplatus , Paragehyra , Christinus , Afrogecko , Cryptactites , Matoatoa , Afroedura , Geckolepis , Homopholis , Blaesodactylus , Goggia , Rhoptropus , Elasmodactylus , Chondrodactylus , Colopus , Pachydactylus , Cnemaspis , Rhoptropella , Lygodactylus , Phelsuma Gecko Geckos are small, mostly carnivorous lizards that have
140-399: A gecko's body temperature is dependent on its environment. Also, to accomplish their main functions; such as locomotion, feeding, reproduction, etc., geckos must have a relatively elevated temperature. All geckos shed their skin at fairly regular intervals, with species differing in timing and method. Leopard geckos shed at about two- to four-week intervals. The presence of moisture aids in
175-399: A point. Gecko skin has been observed to have an anti-bacterial property, killing gram-negative bacteria when they come in contact with the skin. The mossy leaf-tailed gecko of Madagascar, U. sikorae , has coloration developed as camouflage , most being greyish brown to black, or greenish brown, with various markings meant to resemble tree bark; down to the lichens and moss found on
210-487: A reduced but strongly clawed first digit, and lacks movable eyelids . Together, these morphological traits are distinctive of the family Gekkonidae, and also indicate that Y. balticus may have had adhesive abilities similar to modern geckos. Species within the Gekkonidae inhabit every warm region. Furthermore, many genera are capable of widespread geographical habitation, and can be considered invasive in some areas;
245-427: A sharp image for at least two different depths. While most gecko species are nocturnal, some species are diurnal and active during the day, which have evolved multiple times independently. Many species are well known for their specialised toe pads, which enable them to grab and climb onto smooth and vertical surfaces, and even cross indoor ceilings with ease. Geckos are well known to people who live in warm regions of
280-415: A small clutch of eggs. Some are live-bearing, and a few can reproduce asexually via parthenogenesis . Geckos also have a large diversity of sex-determining mechanisms, including temperature-dependent sex determination and both XX/XY and ZZ/ZW sex chromosomes with multiple transitions among them over evolutionary time. Madagascar day geckos engage in a mating ritual in which sexually mature males produce
315-441: A waxy substance from pores on the back of their legs. Males approach females with a head swaying motion along with rapid tongue flicking in the female. Obligate parthenogenesis as a reproductive system has evolved multiple times in the family Gekkonidae. It has been shown that oocytes are able to undergo meiosis in three different obligate parthenogenetic complexes of geckos. An extra premeiotic endoreplication of chromosomes
350-408: A weight of 133 kilograms (293 pounds): each spatula could exert an adhesive force of 5 to 25 nN. The exact value of the adhesion force of a spatula varies with the surface energy of the substrate to which it adheres. Recent studies have moreover shown that the component of the surface energy derived from long-range forces, such as van der Waals forces, depends on the material's structure below
385-598: A wide distribution, found on every continent except Antarctica . Belonging to the infraorder Gekkota , geckos are found in warm climates throughout the world. They range from 1.6 to 60 centimetres (0.6 to 23.6 inches ). Geckos are unique among lizards for their vocalisations , which differ from species to species. Most geckos in the family Gekkonidae use chirping or clicking sounds in their social interactions. Tokay geckos ( Gekko gecko ) are known for their loud mating calls , and some other species are capable of making hissing noises when alarmed or threatened. They are
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#1732775343900420-442: Is 350 times more sensitive than human eyes . The nocturnal geckos evolved from diurnal species, which had lost the rod cells from their eyes. The gecko eye, therefore, modified its cone cells that increased in size into different types, both single and double. Three different photo-pigments have been retained, and are sensitive to ultraviolet, blue, and green. They also use a multifocal optical system that allows them to generate
455-419: Is a misnomer, and is properly called digital hyperextension. Gecko toes can hyperextend in the opposite direction from human fingers and toes. This allows them to overcome the van der Waals force by peeling their toes off surfaces from the tips inward. In essence, by this peeling action, the gecko separates spatula by spatula from the surface, so for each spatula separation, only some force necessary. (The process
490-480: Is being put into these technologies, but manufacturing synthetic setae is not a trivial material design task. Gecko skin does not generally bear scales, but appears at a macro scale as a papillose surface, which is made from hair-like protuberances developed across the entire body. These confer superhydrophobicity , and the unique design of the hair confers a profound antimicrobial action. These protuberances are very small, up to 4 microns in length, and tapering to
525-401: Is essential for obligate parthenogenesis in these geckos. Appropriate segregation during meiosis to form viable progeny is facilitated by the formation of bivalents made from copies of identical chromosomes. Stenodactylus Stenodactylus is a genus of Middle-Eastern and North-African geckos , commonly known as short-fingered geckos . This article about a gecko
560-587: Is only known from a single, stuffed specimen probably collected in the 19th century found in the basement of the Natural History Museum of Marseille in Marseille , France. This gecko was 600 millimetres (24 inches ) long, and it was likely endemic to New Caledonia , where it lived in native forests. The smallest gecko, the Jaragua sphaero , is a mere 16 millimetres (0.63 inches) long, and
595-455: Is similar to removing Scotch Tape from a surface.) Geckos' toes operate well below their full attractive capabilities most of the time, because the margin for error is great depending upon the surface roughness , and therefore the number of setae in contact with that surface. Use of small van der Waals force requires very large surface areas; every square millimetre of a gecko's footpad contains about 14,000 hair-like setae. Each seta has
630-485: Is under discussion, yet recent experiments agree that the presence of molecular water layers (water molecules carry a very large dipole moment) on the setae, as well as on the surface, increase the surface energy of both, therefore the energy gain in getting these surfaces in contact is enlarged, which results in an increased gecko adhesion force. Moreover, the elastic properties of the b-keratin change with water uptake. Gecko toes seem to be double-jointed , but this
665-419: The odontogenic stem cell in the dental lamina . The formation of the teeth is pleurodont ; they are fused (ankylosed) by their sides to the inner surface of the jaw bones. This formation is common in all species in the order Squamata . The infraorder Gekkota is divided into seven families, containing about 125 genera of geckos, including the snake-like (legless) pygopods. Legless lizards of
700-520: The Gekkonidae, as well, but their taxonomic rank is uncertain due to the incompleteness of the fossil remains. Yantarogekko balticus is the earliest known gekkonid gecko. Y. balticus was discovered in Baltic amber dated to the Eocene epoch (56-33.9 million years ago). This species was small, measuring only 20–22 mm from snout to vent . Y. balticus has enlarged, undivided scansorial pads and
735-645: The arboreal Eichstaettisaurus from the Late Jurassic of Germany. Norellius from the Early Cretaceous of Mongolia is also usually placed as a close relative of geckos. The oldest known fossils of modern geckos are from the mid-Cretaceous Burmese amber of Myanmar (including Cretaceogekko ), around 100 million years old, which have adhesive pads on the feet similar to those of living geckos. More than 1,850 species of geckos occur worldwide, including these familiar species: Most geckos lay
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#1732775343900770-401: The bark. It also has flaps of skin, running the length of its body, head and limbs, known as the dermal flap , which it can lay against the tree during the day, scattering shadows, and making its outline practically invisible. As polyphyodonts , geckos can replace each of their 100 teeth every 3 to 4 months. Next to the full grown tooth there is a small replacement tooth developing from
805-406: The course of gecko evolution. Adhesive toepads evolved independently in about eleven different gecko lineages, and were lost in at least nine lineages. It was previously thought that the spatula-shaped setae arranged in lamellae on gecko footpads enable attractive van der Waals' forces (the weakest of the weak chemical forces) between the β-keratin lamellae / setae / spatulae structures and
840-423: The epidermis on the underside of the toes. This was recently discovered in the genus Gonatodes from South America. Simple elaborations of the epidermal spinules into setae have enabled Gonatodes humeralis to climb smooth surfaces and sleep on smooth leaves. Biomimetic technologies designed to mimic gecko adhesion could produce reusable self-cleaning dry adhesives with many applications. Development effort
875-439: The family Dibamidae , also referred to as blind lizards, have occasionally been counted as gekkotans, but recent molecular phylogenies suggest otherwise. Diplodactylidae Carphodactylidae Pygopodidae Eublepharidae Sphaerodactylidae Phyllodactylidae Gekkonidae Several species of lizard from the Late Jurassic have been considered early relatives of geckos, the most prominent and most well supported being
910-431: The feet of geckos are also self-cleaning, and usually remove any clogging dirt within a few steps. Polytetrafluoroethylene (PTFE), which has very low surface energy, is more difficult for geckos to adhere to than many other surfaces. Gecko adhesion is typically improved by higher humidity, even on hydrophobic surfaces, yet is reduced under conditions of complete immersion in water. The role of water in that system
945-533: The genus Eichstaettisaurus display morphological adaptations associated with climbing. Eichstaettisaurus has been ranked as a stem gekkotan, but its true taxonomic rank is unclear. The species Hoburogekko suchanovi and Gobekko cretacicus, dated to the Albian - Aptian ages (121-100 million years ago) ages of the Cretaceous period, are unquestionably members of Gekkota. They are thought to be members of
980-518: The genus Hemidactylus can be identified in all subtropical areas of the world. However, many genera in the family Gekkonidae are endemic. For example, genera Afroedura and Afrogecko are found only in Africa . The range of genus Lepidodactylus stretches from South Asia to Oceania; this genus also accounts for several island species. The genera listed here do not account for all Gekkonidae subspecies and are used only as examples of distribution. For
1015-633: The most species-rich group of lizards, with about 1,500 different species worldwide. All geckos, except species in the family Eublepharidae lack eyelids; instead, the outer surface of the eyeball has a transparent membrane, the brille . They have a fixed lens within each iris that enlarges in darkness to let in more light. Since they cannot blink , species without eyelids generally lick their own brilles when they need to clear them of dust and dirt, in order to keep them clean and moist. Unlike most lizards, geckos are usually nocturnal and have excellent night vision ; their colour vision in low light
1050-418: The outermost atomic layers (up to 100 nm beneath the surface); taking that into account, the adhesive strength can be inferred. Apart from the setae , phospholipids ; fatty substances produced naturally in their bodies, also come into play. These lipids lubricate the setae and allow the gecko to detach its foot before the next step. The origin of gecko adhesion likely started as simple modifications to
1085-457: The shedding. When shedding begins, the gecko speeds the process by detaching the loose skin from its body and eating it. For young geckos, shedding occurs more frequently, once a week, but when they are fully grown, they shed once every one to two months. About 60% of gecko species have adhesive toe pads which allow them to adhere to most surfaces without the use of liquids or surface tension . Such pads have been gained and lost repeatedly over
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1120-464: The surface they are on. The genus Hemidactylus is one of the most species-rich and widely distributed of all reptile genera. The family Gekkonidae is a member of the infraorder Gekkota , which seems to have first emerged during the Jurassic period (201-145 million years ago). Eichstaettisaurus schroederi is recognized as one of the earliest examples of an ancestral gecko species. Members of
1155-543: The surface. These van der Waals interactions involve no fluids; in theory, a boot made of synthetic setae would adhere as easily to the surface of the International Space Station as it would to a living-room wall, although adhesion varies with humidity. However, a 2014 study suggests that gecko adhesion is in fact mainly determined by electrostatic interaction (caused by contact electrification), not van der Waals or capillary forces. The setae on
1190-454: The world, where several species make their home inside human habitations. These, for example the house gecko , become part of the indoor menagerie and are often welcomed, as they feed on insect pests ; including moths and mosquitoes . Like most lizards, geckos can lose their tails in defence, a process called autotomy ; the predator may attack the wriggling tail, allowing the gecko to escape. The largest species, Gigarcanum delcourti ,
1225-400: Was discovered in 2001 on a small island off the coast of Hispaniola . The Neo-Latin gekko and English 'gecko' stem from Indonesian - Malaysian gēkoq , a Malay word borrowed from Javanese , from tokek , which imitates the sounds that some species like Tokay gecko make. Like other reptiles, geckos are ectothermic , producing very little metabolic heat. Essentially,
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