Geckos: The Animal Answer Guide

7. Foods and Feeding

88 Chapter 7 Foods and Feeding What do geckos eat? Nearly all geckos will eat almost any type of arthropod that they can overpower and ingest. Very tiny geckos, like the Dwarf Geckos Coleodactylus or Sphaerodactylus may eat springtails (collembolans) and mites, whereas large geckos may eat larger prey such as orthopterans, beetles, and scorpions . Although some geckos specialize on certain types of prey, most feed on a wide variety, reflecting the relative local diversity and abundance of potential food organisms. Some geckos capitalize on prey items that are superabundant . Barking Geckos, Ptenopus garrulus, collected in Namibia on a rainy night when winged termites were flying had, in some cases, eaten more than half of their own body weight in these insects! The Australian geckos Diplodactylus conspicillatus and Rhynchoedura ornata are among a small set of arid zone geckos only eat termites. When they locate a termite mound or trail, they can fill their stomachs. Termites are patchily distributed , however, and geckos specializing in eating them must endure lean periods in between the good times. Geckos cannot digest leaves and stems easily and only eat them accidentally if ingested with animal prey. However, many geckos will eat high energy, easily digestible plant material, like fruit, sap, nectar, or pollen. This is especially true of geckos occurring on islands, like New Zealand, New Caledonia, Madagascar, and the Mascarene Islands. In some of these areas geckos may take the place of insects as important pollinators and seed dispersers. Larger geckos will eat other vertebrates if they can subdue them. For most geckos, only other small lizards, sometimes of their own species, are small enough. However, the very largest geckos have broader 89 Foods and Feeding diets. Rhacodactylus leachianus will take nestling birds, and Gekko gecko has been observed to eat snakes and small mammals. The Niah Cave Gecko of Borneo, Cyrtodactylus cavernicolus, takes advantage of the swiftlets that nest in the caves where they live and eats hatchling birds that occasionally fall from the cave walls. The only geckos known to truly specialize on vertebrate prey are the large pygopods of the genus Lialis. They are predators of skinks, which they grasp with their highly specialized jaws and teeth and swallow headfirst. Perhaps the broadest diet of any gecko is that of the Gargoyle Gecko, Rhacodactylus auriculatus. Although also a generalist insectivore , it is known to also eat snails, flowers, sap, skinks, and other geckos. Regardless of their diet, geckos, and especially nocturnal geckos, appear to have empty stomachs more often than other lizards do. This is particularly true at cooler times of year when both prey availability and the metabolic demands of the gecko are lower. Insects and other arthropods make up the bulk of the diet for most geckos, including the Leopard Gecko (Eublepharis macularis), making them one of the most important of all nocturnal insectivorous vertebrates after bats. Courtesy of Tony Gamble. Island geckos often eat fruit, nectar, or pollen and may be important pollinators or seed dispersers. The Bluetail Day Gecko (Phelsuma cepediana ) of Mauritius is the only known pollinator and seed disperser of the rare plant Roussea simplex. Courtesy of D. M. Hansen. 90 Geckos: The Animal Answer Guide How many teeth do geckos have? Gecko teeth are small and numerous and usually similar in size and shape throughout the jaws. The teeth are present on the premaxilla and the maxillary bones in the upper jaw and on the dentary bone in the lower jaw. There are usually 9–13 teeth (typically a set number for a given species) in the premaxilla no matter how big the gecko is, but the number on the other elements is variable and increases as the animal grows and the dental lamina, the area where teeth form, elongates. The total of the teeth in the upper jaws is usually slightly greater than those in the lower jaw. The total number of teeth varies over time, as the teeth may be lost and replaced; thus, it is best to refer to the number of tooth loci, or the number of spots where teeth are either present or may be replaced. Most adult geckos have between 50 and 80 tooth loci in both the upper and lower jaws. However, the Leaf-tailed Gecko, Uroplatus fimbriatus, has the greatest number of teeth (more than 300 in total) of any gecko.This is probably the greatest number of teeth in any...