Geckos: The Animal Answer Guide

1. Introducing Geckos

What are geckos? Geckos are a type of lizard. They are generally small-bodied, fully limbed, nocturnal predators that have good vision and vocal capabilities, usually lack movable eyelids, and often have adhesive pads on their toes. Lizards and snakes, along with amphisbaenians (worm lizards), constitute the order Squamata, or scaled reptiles. Squamates are one of several major groups of vertebrates. They are amniote vertebrates, meaning that they belong to the group of vertebrates that has “escaped” from reliance on water for reproduction by evolving an egg that contains an amniotic membrane. Water is kept in but gases, like oxygen, can move freely in and out of the egg. This lets the young to undergo development in even the harshest arid environments. Other living amniotes include mammals, birds, turtles, and crocodilians. The last two of these are often combined with squamates in the Class Reptilia . Although this group is familiar to almost everyone, it is not a “natural ” group in an evolutionary sense. In other words, some reptiles are more closely related to nonreptiles than to other groups of reptiles. Thus, crocodilians are more closely related to birds than they are to the superficially more similar lizards. We know this to be true because there is a great deal of evidence from comparative anatomy and paleontology and from genetic data. Lizards, crocodilians, and another group of reptiles closely related to squamates—tuataras—are similar in overall appearance, because they walk on four legs and have a scale-covered body. They also share physiological similarities such as ectothermy (a reliance on external heat sources to maintain body temperature) and poikilothermy (the inability to physiologically Chapter 1 Introducing Geckos 1 2 Geckos: The Animal Answer Guide regulate temperature). These similarities confused scientists like Carolus Linnaeus (1707–1778), who originally classified not only crocodilians but even salamanders (a type of amphibian) as lizards. Only in the early nineteenth century were the distinctions between amphibians and reptiles clarified and the great differences among groupings (families) of lizards recognized. Where does the name “gecko” come from? The word “gecko” or “gekko” is widely used in English and many other European languages to refer to fully limbed gekkotan lizards. It was in wide use by the mid-eighteenth century and was used by Linnaeus in 1758 when he described the Tokay Gecko as Lacerta gecko (now Gekko gecko).The earliest European works in natural history used the Greek-derived name ascalabotes or the Latin stellio (both meaning a spotted lizard) or lacertus facetanus (clever lizard) for geckos. “Gecko” did not appear in Western literature until the seventeenth century, when commercial trade with tropical Asia was well established. The first known usage of the word in the Western world was in a book by Bontius (1658) in which he discussed the animals and plants he had encountered in the East Indies (modern Indonesia) some 30 years before. This and other early references suggest that the name was an imitation of the vocalizations made by this lizard. The Oxford English Dictionary derives “gecko” from the Malay gēkoq (sometimes written as kēko or gago), itself an onomatopoeic word based on the sounds made by the Tokay Gecko (tāké, goké, and tōkē are also Malay words for gecko). An alternative possible origin comes from Sri Lanka. Although the modern Sinhalese (the language of the largest ethnic group in Sri Lanka) words for geckos are hūna or sūna, Sri Lankan works written between the eleventh and fifteenth centuries record gēgo (gē = house + go = goya = lizard = house lizard) as the Elu (the precursor of modern Sinhala) name for gecko. Dutch ships bound for the East Indies in the seventeenth and eighteenth centuries regularly called at Sri Lankan ports en route to Ambon and Java, but by this time gēgo was no longer in local use. However, cultural, political, and military connections between Sri Lanka and southeast Asia between the sixth and thirteenth centuries may have provided opportunities for linguistic influences between the two regions. Despite the apparently different meanings of the words, gēkoq and gēgo may ultimately share a partly common origin. Why are geckos important? Geckos are important for several reasons. They are key components in many tropical and subtropical ecosystems, from deserts to rainforests, 3 Introducing Geckos where they are both predators and prey. Most geckos feed on insects and other arthropods and contribute...