Class - Reptilia
Order - Squamata
Clade - Gekkonomorpha
Infraorder - Gekkota
Geckos are little carnivorous lizards found on every continent except Antarctica. Geckos are found in warm areas all over the world and belong to the infraorder Gekkota. They are 1.6 to 60 cm in length (0.64 to 24 inches).
Geckos are distinguished from other lizards by their vocalizations, which vary by species. In their social interactions, most geckos in the Gekkonidae family make chirping or clicking noises. When scared or threatened, Tokay geckos (Gekko geckos) are famed for their loud mating cries, and certain other species can make hissing noises. With over 1,850 distinct species worldwide, they are the most diverse group of lizards.
Except for members of the Eublepharidae family, all geckos lack eyelids; instead, the cornea, a transparent membrane, covers the outer surface of the eyeball. Each iris has a fixed lens that enlarges in darkness to let in more light. Because they can't blink, creatures without eyelids lick their own corneas to keep them clean and moist when they need to cleanse them of dust and debris.
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| Licking cornea to clear it of dust. |
Nocturnal animals have superb night vision, with 350 times the sensitivity of human color vision in low light. Diurnal geckos that had lost their eye rods developed into night geckos. Geckos, like most lizards, can lose their tails in defense, so the predator will attack the tail first, allowing the gecko to flee before the predator notices, a process known as autotomy. Many species are noted for their specialized toe pads, which allow them to easily climb smooth and vertical surfaces, as well as span interior ceilings. People who live in warm climates are familiar with geckos, as some species build their homes within human dwellings. These (such as the house gecko) form part of the indoor menagerie and are frequently appreciated since they eat insects such as moths and mosquitoes. Geckos, unlike other lizards, are nocturnal.
The kawekaweau (Hoplodactylus delcourti), the biggest species, is only known from a single stuffed specimen discovered in the basement of a Marseille museum. This 60-centimeter (24-inch) long gecko was most likely unique to New Zealand, where it lived in native woods. It was likely wiped off, along with much of the natural fauna of these islands, in the late 19th century, when new invasive species like rats and stoats were introduced during European colonization. The Jaragua sphaero, the world's tiniest gecko, is about 1.6 cm (about half an inch) long and was discovered on a tiny island off the coast of Hispaniola in 2001.
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Common Details
Geckos, like other reptiles, are ectothermic, meaning they produce relatively little metabolic heat. The body temperature of a gecko is largely determined by its surroundings. Furthermore, geckos require a somewhat high temperature to perform their primary tasks, such as movement, eating, breeding, and so on.
Shedding/molting
All geckos shed their skin at around the same time each year, however, the timing and technique vary by species. Leopard geckos lose their skin every two to four weeks. Moisture contributes to the process of shedding. When shedding begins, the gecko accelerates the process by removing and devouring the loose skin of its body. Geckos shed once a week when they are young, but after they are fully grown, they shed once every one to two months.Ability of Adhesions
Around 60% of gecko species have sticky toe pads, which enable them to stick to most surfaces without the need for liquids or surface tension. Over the history of gecko development, such pads have been obtained and lost several times. Adhesive toepads developed separately in around 11 gecko lineages and were lost in at least 9 of them.
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| The underside of a gecko's foot |
The attractive van der Waals' forces (the weakest of the weak chemical interactions) between the β-keratin lamellae/setae/spatulae structures and the surface are enabled by the spatula-shaped setae grouped in lamellae on gecko footpads. There are no fluids involved in these van der Waals interactions; in principle, a boot constructed of synthetic setae might attach to the International Space Station's surface as readily as a living-room wall, however, adherence varies with humidity.
Skin
Gecko skin does not have scales and instead appears as a papillose surface made up of hair-like protuberances that grow throughout the entire body on a macro scale. Superhydrophobicity is conferred, and the hair's unique pattern gives a powerful antibacterial effect. These protuberances are extremely minute, measuring up to 4 microns in length and ending in a point. The skin of geckos has been found to have antibacterial properties, killing gram-negative bacteria that come into contact with it.
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| Gekko gecko skin |
The coloring of Madagascar's Mossy Leaf-tailed Gecko, U. Sikora, has been created for camouflage, with the majority of the animals being grayish brown to black or greenish-brown with varied patterns meant to simulate tree bark, even down to the lichens and moss found on the bark. It also possesses dermal flaps, which span the length of its body, head, and limbs and may be laid against the tree during the day to disperse shadows and make its form virtually undetectable.
Teeth
Geckos are polyphyodonts, meaning they may replace all 100 of their teeth every three to four months. A little replacement tooth is growing next to the fully developed tooth in the dental lamina, thanks to an odontogenic stem cell. The teeth are formed in a pleurodont manner, with their sides bonded (ankylosed) to the inner surface of the jawbones. All species in the Squamata order have this structure.
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| Leopard gecko teeth |
Distribution
Geckos are mostly found in the tropics and subtropics, however, certain species have been found as far north as the southwestern United States, southern Europe, and southern Siberia. Geckos in the southern hemisphere reach Stewart Island in New Zealand and the southernmost point of South America. Geckos may be found up to 12,000 feet (3,700 meters) in the Himalayas, however, they are more abundant at lower levels. Most tropical and subtropical islands host geckos, and geckos, along with skinks, are sometimes the sole terrestrial reptiles on distant oceanic islands.
Some gecko species, such as the house gecko (Hemidactylus frenatus) and the mourning gecko (Lepidodactylus lugubris), have large geographic ranges, although most are limited to small areas. Many geckos have specific substrate preferences, preferring just certain types of rocks, trees, or soils. Gecko diversity is particularly great in Africa and Australia's dry and semiarid environments, as well as in Southeast Asia and Madagascar's wooded areas. North America, Europe, and temperate Asia are home to a small number of species. Some geckos coexist with people and are easily transferred.
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| Common house gecko ( Hemidactylus frenatus ) Copyright ©- flickr.com |
Classification
The Gekkota infraorder is organized into seven families, with roughly 125 geckos genera, including the snake-like (legless) pygopods.
- Carphodactylidae
- Diplodactylidae
- Eublepharidae
- Gekkonidae
- Phyllodactylidae
- Pygopodidae
- Sphaerodactylidae
Cretaceogekko and Yanatarogecko are two extinct geckos that cannot be classified into any of these seven families. Legless lizards of the Dibamidae family, popularly known as blind lizards, have been mistakenly classified as gekkotans in the past, but current molecular phylogenies show otherwise.
Feeding ecology/diet
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| Leopard geckos ( Eublepharis macularius ) eat insects. Copyright © - azreptiles.org |
Insectivorous diets are consumed by nearly all geckos. The majority of tiny species solely feed arthropods, however, some larger species also eat small vertebrates. Ex:- Tokay geckos (Gekko geckos).
tiny snakes, lizards, and mammals, as well as nestling birds, are overpowered and eaten. Rhacodactylus auriculatus, a New Caledonian gecko species, with specialized fanglike teeth for penetrating the bodies of other lizards. Burton's snake lizard (Lialis burtonis) possesses hinged teeth that allow it to eat hard-bodied food like tiny skinks, which have osteoderms to strengthen their skins (bony plates embedded in the skin).
Both diurnal and nocturnal geckos in New Zealand and neighboring islands frequently augment their diet with plant fruits, nectar, or pollen. These lizards may serve a significant function as both pollinators and seed dispersers in some circumstances.
Geckos use a mix of visual and chemical signals to find food. Eublepharines, like other geckos, forage widely and rely on chemical signals to find food. The majority of other species, on the other hand, are ambush predators that move slowly and rely on eyesight to recognize arthropod prey that approach within striking distance.
Reproduction
Males of several species call to attract females. The bell geckos (Ptenopus) of southern Africa take this to an extreme, with males participating in choruses. Males try to attract mates by shouting from the entrances of their burrows, which act as resonating chambers to magnify the sound. Chemical signals can be used by less vocal geckos, such as leopard geckos (Eublepharis macularius), to recognize individuals of the opposing sex, while many others can visually distinguish mates at close range. Before mating, male geckos massage or kiss females and restrain them during copulation by biting them on the nape of the neck or back. Males are absent in the mourning gecko (Lepidodactylus lugubris) and a few other species. These unisexual species are the result of the hybridization of two bisexual parental species and reproduce clonally by parthenogenesis once established.
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| Leopard Geckos Breeding Copyright ©- geckotime.com |
The majority of geckos lay eggs. The eggs of gekkonine geckos have a hard shell, but the eggs of the other subfamilies have a leathery shell. Females lay eggs in protective areas, such as the axils of leaves, under bark, or in shallow nests in the soil, which often create a high-humidity microclimate. Desert geckos deposit their eggs in tunnels or rock crevices or on vertical or overhanging rock surfaces in flattened, adhesive eggs.
The clutch size of all geckos is the same. The majority of species produce two offspring in a clutch, while a few small groups of species create just one egg at a time. Tropical species may have numerous clutches each year, sometimes just during wetter seasons, although cooler-temperature species usually only have one clutch every year.
Geckos usually leave their eggs after one to six months of development, depending on temperature. The sex of the progeny in eublepharines and some gekkonines is temperature-dependent. The average temperature of growing embryos throughout the second trimester of development determines the gender of the geckos, with higher temperatures resulting in males and lower temperatures resulting in females. Hatchling geckos use paired egg teeth to slice their eggshells, which are shed shortly after eclosion (hatching). New Zealand geckos, as well as one species in adjacent New Caledonia, are the only ones in the world that are viviparous (live-bearing) and have a simple placenta. These species usually produce twins, with gestation periods ranging from 4 to 14 months.
Conservation
Only a few geckos have population estimates, and the conservation status of the majority of species is unclear. Many geckos dwell in arid places where people have little influence, or, like other tropical species, they actively seek out human settlements for their own benefit. However, habitat deterioration, notably deforestation, and the invasion of rats, cats, and other predatory animals threaten many island-dwelling geckos with limited ranges. The Giant gecko of Round Island in the Mascarenes (Phelsuma edwardnewtoni) and Delcourt's gecko, the biggest gecko ever alive, are among the few geckos thought to have gone extinct in historical times.
New Zealand's huge gecko. Introduced predators were most likely to blame in each case. Because they are extensively marketed in the pet trade, geckos of the genus Phelsuma, which are notably vividly colored and beautiful, are all globally protected as CITES Appendix II species.
Relations with humans
Large geckos, such as the Fijian voracious gecko (Gehyra vorax), were historically sought for food, although geckos are now mostly used for medical purposes. Tokay geckos and other species are sold dried or pickled in wine or spirits in China and Southeast Asia to boost vitality and heal renal problems. House geckos are popular among herpetoculturalists in Europe and North America, and they are appreciated as predators of insect pests throughout most of the tropics. Although all geckos are harmless, their strange nocturnal habits, huge eyes, and climbing ability have been misinterpreted as indicators of evil, and they are wrongly considered as poisonous to the touch in some cultures.
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| Tokay geckos (Gekko gecko) used to make some wine |
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