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Home , Atlas day gecko, Christinus, Christinus marmoratus, Diplodactylinae, Eurydactylodes, Gekkonidae

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GEKKONIDAE: GENERAL NOTES

Standing’s Day standing

PHYLUM / SUBPHYLUM Chordata / Vertebrata CLASS Reptilia ORDER / SUBORDER / Lacertilia FAMILY / SUBFAMILY / 5 Subfamilies (see Chart) / 100+ Genera / 1,000+ Species

Well-known gekkonids include: Flying Gecko, House Gecko, Knob-tailed Gecko, Mediterranean Gecko, Mourning Gecko, Standing’s Day Gecko*, . (*: PZ)

PZ gekkonids include: Standing’s Day Gecko.

GEOGRAPHIC RANGE Worldwide in tropical, subtropical and some warm temperate areas. Can range as far north as the southwestern U.S., southern Europe and southern Siberia. To the south, can reach Stewart Island in New Zealand and approach the southern tip of South America. Few species live in North America, Europe or temperate Asia.

HABITAT Desert, forest, savanna, grassland. Most live in arid and semiarid habitats in Africa and and in forested parts of S.E. Asia and Madagascar. Most common at lower elevations, but can be found up to 12,000’ in the Himalayas.

TOURING HIGHLIGHTS - The feet are one of the most striking and varying aspects of the morphologic characteristics of geckos. Eublepharines and some gekkonines and diplodactylines have slender digits with well-developed claws, but many species have expanded pads on the base and or tips of the toes that permit to smooth surfaces. These pads may be distal (at the tips of the toes) and fan-shaped (Pteyodactylus) or leaf-shaped () or they may be basal (at the base of the toes) and arranges in single () or divided () rows. The first digits of the hands and feet may be reduced in size, but it is never lost entirely.

Gekkonidae: General Notes 2/8

- The toes of the gecko have developed a special adaptation that allows them to adhere to most surfaces without the use of liquids or surface tension. Recent studies of the spatula tipped setae on gecko footpads demonstrate that the attractive forces that hold geckos to surfaces are van der Waals interactions between the finely divided setae and the surfaces themselves. Every square millimeter of a gecko's footpad contains about 14,000 hair-like setae. Each has a diameter of 5 micrometers. Human hair varies from 18 to 180 micrometers, so a human hair could hold between 3 and 36 setae. Each seta is in turn tipped with between 100 and 1,000 spatulae. Each spatula is 0.2 micrometers long (200 billionths of a meter), or just below the wavelength of visible light. - These van der Waals interactions involve no fluids; in theory, a boot made of 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 and is dramatically reduced under water, suggesting a contribution from capillarity. The setae on the feet of geckos are also self cleaning and will usually remove any clogging dirt within a few steps. Teflon, which has very low van der Waals forces, is the only known surface to which a gecko cannot stick. Geckos' toes seem to be "double jointed", but this is a misnomer. Their toes actually bend in the opposite direction from human fingers and toes. This allows them to overcome the by peeling their toes off surfaces from the tips inward. In essence, this peeling action alters the angle of incidence between millions of individual setae and the surface, reducing the van der Waals force. Geckos' toes operate well below their full attractive capabilities for most of the time. This is because there is a great margin for error depending upon the roughness of the surface, and therefore the number of setae in contact with that surface. If a typical mature 2.5 oz. gecko had every one of its setae in contact with a surface, it would be capable of holding aloft a weight of 290 lb.: each spatula can exert an force of 10 nanonewtons (0.0010 mgf). Each seta can resist 10 milligrams-force (98 N), which is equivalent to 10 atmospheres of pull. This means a gecko can support about 8X its weight hanging from just one toe on smooth glass. - Geckos are unique among in their vocalizations, making chirping sounds in social interactions with other geckos. - In the Mourning Gecko ( lugubris) and a few other species, there are no males. Such unisexual species have arisen from the hybridization of two bisexual parental species and, once established, reproduce clonally by parthenogenesis. - Most geckos lay eggs but the geckos of New Zealand and one species in are live-bearing (viviparous) and possess a simple placenta. These species always produce twins which may gestate for 4-14 months.

SURVIVAL STATUS AND / OR CONSERVATION - IUCN: 31 species (Extinct, 3 species; Extinct in the Wild, 1 species; Critically Endangered, 1 species; Endangered, 3 species; Vulnerable, 15 species; Lower Risk/Near Threatened, 8 species). - CITES II: the especially brightly colored and attractive geckos of the genus Phelsuma are popular in the pet trade. - Population estimates exist for very few geckos and the conservation status of most species is unknown. - Many geckos live in desert areas that are affected little by humans or, like some tropical species, actually exploit human habitation for their own use.

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- Many island-dwelling geckos with restricted distributions, however, are imperiled by habitat destruction, particularly deforestation, and by the introduction of rats, cats and other predatory mammals.

ENEMIES AND / OR DEFENSE - Enemies: spiders, introduced exotic species (rats, stoats). - Defense: geckos use vocalizations, in combination with bites and defecation, to deter predators. - Defense: many geckos have cryptic coloration or outline-concealing skin folds and flaps to avoid detection. - Defense: a few geckos, such as the ( afer) can outrun most predators. - Defense: tail autotomy is common. Threatened geckos lure predators to attack the tail, which continues to wriggle after it is shed, distracting the predator and allowing the gecko to escape. The loss of the tail usually carries with it a significant energetic cost, but, in the Marbled Gecko ( marmoratus), tail loss has the immediate benefit of increased running speed. - Defense: certain geckos, mostly island species, can shed large portions of their body skin if they are grasped by predators and they can regrow skin over the large wounds. - Defense: members of 2 genera of diplodactyline geckos ( and ) can ooze or squirt a sticky fluid from their tails that can entangle the mouth parts of such predators as spiders.

PHYSICAL - Configuration: small to medium size, stocky, flattened bodies with large heads. - Size: average 1.2”-3.5” (range 0.6”-10”) snout-vent length. The smallest gecko, the Jaragua Sphaero (Sphaerodactylus ariasae), discovered in 2001, averages only 0.63” in snout-vent length. The New Caledonian Giant Gecko ( leachianus) reaches 10”. - Color: often drab. Browns and grays are the most common colors and diffuse patters of chevrons or crossbars characterize many species. In diurnal forms, such as the Malagasy Day Gecko (Phelsuma), bright greens, yellows, reds and blues may be encountered. - Skin/Scales: usually covered with small granules, with or without larger keeled tubercles (enlarged scales with a raised ridge) intermixed. Many species have loose, velvety skin made up of minute granular scales, whereas others have a dorsal surface with clusters of pronounced tubercles surrounded by smaller scales. Abdominal scales are often large, plate- like and overlapping. - Body: stout, shortened and somewhat flattened. - Head: large, diamond-shaped. - Eyes: large, set laterally on a sloping forehead. All geckos, excluding the Eublepharinae subfamily, have no eyelids and, instead, like , have a transparent membrane, a clear, protective covering over the eyes, which they lick to clean with their protrusible notched tongue. The pupils of common nocturnal species are vertical and are often lobed in such a manner that they close to form four pinpoints. A feature of nocturnal geckos in which they differ from most other vertebrates, is that they only have cones in their retinas and their pupils are narrow and vertical to block out light. Other geckos have round pupils. - Ears: auditory openings are generally round to oval in shape. - Snout: short, blunt. Gekkonidae: General Notes 4/8

- Jaws: large, hard, shiny nasal and chin shields cover the margins of the jaws and nasal area and contrast markedly with the dull and velvety head and body scales. - Tongue: wide, flat with a notch in its leading edge and frequently used for licking the face and eyes. - Dentition: typically pleurodont and the teeth are numerous. They range from small, conical, homodont and pleurodont, occurring on the dentary, maxilla and premaxilla. The anterior teeth are generally larger than the posterior teeth. Palatine teeth are absent. - Tail: may be long and tapering, short and blunt, or even globular. The tail serves in many species as an energy storehouse on which the can draw during unfavorable conditions. The tail may also be extremely fragile and, if detached, is quickly regenerated in its original shape. It is prehensile in some species. - Limbs: well-developed, with larger hind limbs than forelimbs. Geckos have well-developed, pentadactylic limbs with complex modifications to toe shape. Some rock-dwelling and arboreal species have pad-like toes with complex subdigital lamellae, although others retain primitive claw-like toes without laterally expanded pads. Some terrestrial forms also share lamellar specialization, whereas others have simple toes. The individual lamellae are actually compound pads made up of microscopic projections or setae which take hold on the substratum. - Feet: Most geckos have feet modified for climbing. The pads of their long toes are covered with small plates that are in turn covered with numerous tiny, hair-like processes that are forked at the end. These microscopic hooks cling to small surface irregularities, enabling geckos to climb smooth and vertical surfaces and even to run across smooth ceilings. Some geckos also have retractable claws. - Glands: the males of many species possess a series of precloacal glands or femoral pores, or both, on the ventral surface of the groin and thighs.

LONGEVITY - In wild: 5-7 years average, up to 11+ years. - In captivity: 5-7 years average, up to 11+ years.

ACTIVITY PERIOD - Most species (75%) are nocturnal and emerge from hiding in the early evening to forage and seek mates. Because they gain most of their heat via conduction from warm surfaces, their body temperatures drop as the night progresses and activity may be limited to just a few hours at cooler times of the year. - Diurnal geckos may have 1-2 peaks of activity during the day, often in the late morning and again in the mid-to-late afternoon.

DIET AND FEEDING - In wild: arthropods and : flies, spiders, termites. - In zoo: crickets, worms, baby food with calcium/mineral mix supplement.

- Most geckos are dietary generalists which prey on various arthropods and occasionally small vertebrates, and eat some plant material - Geckos can be voracious predators and will actively pursue and kill their prey. Generally they attack moths and arthropods by running up to the animal, biting down on it and then beating the prey on the ground by shaking the head laterally. The geckos’ head size governs Gekkonidae: General Notes 5/8

the size of large insects which can be eaten. The prey is orientated longitudinally in the gecko’s mouth, so that protrusions, such as an ’s legs, fold back, thus avoiding obstruction. The prey is swallowed with assistance from the tongue, muscular contractions in the neck and body, and by progressive biting and swallowing. - Nearly all geckos survive on insectivorous diets. - Most small species eat only arthropods. - Some larger species take small vertebrate prey. Tokay Geckos (Gekko gecko) can overpower and eat small snakes, lizards and mammals as well as nestling . - In New Zealand and on other islands, both diurnal and nocturnal geckos often supplement their diet with the fruits, nectar or pollen of plants. In some cases, these lizards may play important roles as both pollinators and seed dispersers. - Geckos hunt using a combination of visual and chemical cues. - Some forage widely and use chemical cues to locate prey. (Eublepharines) - Most are ambush predators, moving little and relying on vision to identify arthropod prey that come within striking range.

BREEDING AND REPRODUCTION AND CARE OF THE YOUNG - Courtship: males of some species attract females by calling. Individual males try to attract mates by calling from their burrow entrances which serve as resonating chambers to amplify the sound. Less vocal geckos can identify members of the opposite sex by chemical cues and many others identify mates visually at close range. - Mating: males rub or lick females before mating and restrain them during copulation by biting them on the nape of the neck or the back. - Eggs: most geckos lay eggs. In gekkonine geckos, the eggs are hard-shelled, but, in the remaining subfamilies, they are leathery. Females lay eggs in protected sites that often provide a high humidity microclimate. Desert geckos lay eggs in burrows or rock crevices or lay flattened, adherent eggs on vertical or overhanging rock surfaces. - Clutch: all geckos have fixed clutch sizes. Most produce 2 young in a clutch, but a few groups of mostly smaller species produce a single egg at a time. Tropical species may produce several clutches a year, sometimes only during wetter periods, but those in cooler climates often have only a single clutch in a year. - Development: geckos typically abandon their eggs and development takes 1-6 months, depending on the temperature. In eublepharines and some gekkonines, the sex of the offspring is temperature-dependent. The average temperature experienced by developing embryos during the second trimester of development determines what sex the geckos will become, with higher temperatures yielding males and lower temperatures yielding females. - Hatchlings: hatchlings slit their eggshells with paired egg teeth that are shed shortly after hatching. - Sexual maturity: 2 years.

SOCIAL STRUCTURE AND INTERACTION AND COMMUNICATION - Many geckos are relatively solitary, though Bibron’s Gecko (Patchydactylus bibronii) and some other species can reach very high densities and may share retreat sites. These geckos have reduced levels of aggression toward one another, but there is little evidence of a complex social structure. Gekkonidae: General Notes 6/8

- Many geckos, especially males, actively defend important resources, such as retreat sites and feeding areas. These geckos stave off rivals of their own and other species by vocalizing, using complex patterns of clicks and chirps. - Unlike other , most geckos have a voice, the ability to produce sounds. The calls differ with the species and range from a feeble click or chirp to a shrill cackle or bark. Some make high pitched calls, some sound like ducks and others like barking dogs. - Calls usually take two forms. In the first of these, gekkonine and diplodactyline geckos produce defensive or distress calls when threatened. In the , these may be a simple chirp, or scream. In the Diplodactylini, aggressive threat calls may be accompanied by back-arching, leg-extension and mouth-opening. Calls of the second form are associated with contact in territoriality or mate attraction. These contact calls consist of multiple chirps and are known from a number of gekkonine genera

LIFE STYLE AND LOCOMOTION - Geckos are both terrestrial and arboreal in life style. - Tropical species are active year-round, but in the north and south of the family’s distribution, geckos remain inactive, deep in burrows or crevices, during cold periods. They rarely cease all activity, however, and can emerge or take advantage of warmer nights. - Many geckos are substrate-limited and prefer only particular types of rocks, trees or souls. - In arid zones, geckos often occupy narrow rock crevices or else they burrow, creating shallow tunnels or occupying those of other in sandy soils. - A few species, such as the Web-footed Gecko (Palmatogecko rangei), are specialists of dune faces. - Some arid-zone geckos live and forage in grass hummocks. - Humid tropical forest habitats are used widely by geckos, which may live on the trunks or branches or in the canopy of trees, under rotting logs or on rocks along streams and rivers. - In savannas and grasslands, geckos are less numerous and often patchily distributed, using trees, rocks or termite nests as shelter. - A small, but conspicuous, minority of geckos favor the walls of buildings or other manmade structures, where artificial lighting attracts insect prey. - When stressed by temperatures approaching their critical thermal maximum, geckos open their mouths and pant; also fluttering of the gular area, presumably increasing air flow and evaporative cooling efficiency. Nevertheless, many species attempt to avoid thermal stress by sheltering in burrows and only emerge in the cool of the evening. - Modifications in skeletal structure permit adjustment between the position of the tibia and tarsus to provide a laterally projecting hind foot, as is also true of the forearm and manus of the front foot. Such adaptations are important in the gekkonids with their highly specialized foot structures and surface attachment mechanisms, and permit geckos to run at great speed on a range of surfaces. - Hyperextension is basic to the function of adhesive pads in the Gekkonidae. The thousands of microscopic setae present on the adhesive subdigital lamellae of the toes of geckos, can engage microscopic irregularities on the surface on which the animal is climbing, such that a pad makes contact and effectively hooks on to a surface. To remove the pad, the gecko must detach the pad in the opposite direction to which it was applied. To achieve release, blood is forced into sinuses within the toes, the muscles dilate and the phalanges disarticulate, thus changing the position of the setae. The toes can be curled back as the setae are effectively Gekkonidae: General Notes 7/8

disengaged. This obligatory locomotory mode permits the gecko to walk on and adhere to smooth, vertical surfaces and even hang on the lower side of horizontal surfaces. It is noteworthy that the positioning of the feet obliquely to the body, plus the radiation of the toes on each foot, spanning over 200° of arc, provides all-round support for the animal and thus consolidates an otherwise precarious attachment.

FAMILY: GEKKONIDAE

Subfamily Aleuroscalabotinae Eublepharinae Gekkoninae Teratoscincinae Genera 1 5 17 74 1 Species 1 27 121 930 7 Members Cat geckos Eyelid geckos , Common Wonder geckos clawless, knob- geckos tailed, leaf- tailed, spiny- tailed, thick- tailed, velvet geckos Geographic Indonesia, Worldwide, in Australia, New Worldwide, Qatar, United Range Malaysia, North and Caledonia, New throughout Arab Emirates. Singapore, Central Zealand the tropics Oman, west in Cambodia, Thailand America, Asia and sub- Iran, Afghanis- (including tropics tan, Pakistan, Japan) and north to Russia, Africa Kazakhstan, Turkmenistan, Uzbekistan, Tajikistan to Mongolia, China.

Continued Gekkonidae: General Notes 8/8

REFERENCES - Hutchins, Michael, James B. Murphy, and Neil Schlager (eds.). 2003. Grzimek’s Animal Life Encyclopedia. Second Edition. Vol. 7: Reptiles; Turtle & Tortoises to Lizards & Snakes. Farmington Hills, MI: The Gale Group. - King, Max and Paul Horner. Fauna of Australia 2A - Reptilia - Squamata - Gekkonidae 27. Family Gekkonidae. http://www.environment.gov.au/biodiversity/abrs/publications/fauna-of- Australia/pubs/volume2a/27-fauna-2a-squamata-gekkonidae.pdf www.environment.gov.au/biodiversity/abrs/publications/... - "gecko." Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica, 2011. http://www.britannica.com/EBchecked/topic/227649/gecko - Gekkonidae. zipcodezoo.com/Key/Animalia/Gekkonidae_Family.asp - The Database. www.reptile-database.org.

Prepared by: Judith Ehrman, docent Date: 04-18-11 Photo by: John Bernard, docent Map by: Judith Ehrman - Bob Sloane, docents Approved by: Jason Bell, Assistant Curator, Reptiles and Date: 04-21-11 Amphibians