Crested gecko

Appearance

The crested gecko has hair-like projections found above the eyes, resembling eyelashes. It has a wedge-shaped head and a crest that runs from each eye to the tail. Crested geckos do not have eyelids and so they use their long tongues to moisten their eyes and remove debris. The toes and the tip of the semi-prehensile tail are covered in small hairs called setae. Each seta is divided into hundreds of smaller hairs called spatulae. It is believed these structures exploit the weak van der Waals force to help the gecko climb on most solid surfaces. The toes have small claws which aid in climbing surfaces to which their toes cannot cling. They possess a prehensile tail which they use to assist in climbing. The tail can be shed as a deterrent to predators. Unlike some other geckos, once they lose their tail it will not grow back; however, this is not as harmful to the gecko as it is to others, such as the Leopard gecko.

The crested gecko has many naturally occurring color groups, some of which include: grey, brown, red, orange, and yellow of various shades. They have variable markings, which include spots, straight stripes, and tiger-like stripes. The colors are brighter and more prominent at night.

The crested gecko has distinct structural morphs in head size and crest abundancy. Geckos with a head length less than 1.3 times its width are considered "crowned" crested geckos. They can vary in the amount and size of the crests; some have crests that extend to the base of the tail and some lack crests on one side of their body.

Distribution

The crested gecko is endemic to South Province, New Caledonia. There are three disjunct populations, one found on the Isle of Pines and surrounding islets, and there are two populations found on the main island of Grande Terre. One population is around the Blue River, which is a protected provincial park, and the other is further north, just south of Mount Dzumac.

Status

Long believed extinct, the species was rediscovered in 1994 after a tropical storm. It is currently being assessed for CITES protection and vulnerable status. The biggest single threat to the wild population appears to be the introduction of the little fire ant to New Caledonia. The ants prey on the geckos, stinging and attacking in great numbers and also compete with the geckos for food by preying on arthropods.

Behavior

The crested gecko has no eyelids; a transparent scale, or spectacle, keeps its eyes moist and it uses its tongue to clear away debris, this is called a brill. Like all ''Rhacodactylus'' and related geckos, it has webbing on its legs and digits. They are a mostly arboreal species, preferring to inhabit the canopy of the New Caledonian rainforests, and because of this they can jump considerably well. They are primarily nocturnal, and will generally spend the daylight hours sleeping in a secure spot in a tree. Unlike most arboreal geckos however, its not as strong a climber as those of the Tokay Gecko species, its foot pads are less able to grip than its cousins.

The crested gecko, unlike the closely related gargoyle gecko , will not regrow its tail once lost. The cells around the base of the tail are brittle, allowing the tail to break away when threatened or caught by a predator. The capillaries to the tail will close almost instantly so there is little to no blood loss. The tails will move independently of the body for 2–5 minutes. The loss of their tail is not problematic, and most adults in the wild do not have their tails.

Unlike most species of gecko, this species is an omnivore, also considered frugivorous, feeding on a variety of insects and fruit. In captivity, they prefer to eat crickets.

Habitat

The crested gecko has no eyelids; a transparent scale, or spectacle, keeps its eyes moist and it uses its tongue to clear away debris, this is called a brill. Like all ''Rhacodactylus'' and related geckos, it has webbing on its legs and digits. They are a mostly arboreal species, preferring to inhabit the canopy of the New Caledonian rainforests, and because of this they can jump considerably well. They are primarily nocturnal, and will generally spend the daylight hours sleeping in a secure spot in a tree. Unlike most arboreal geckos however, its not as strong a climber as those of the Tokay Gecko species, its foot pads are less able to grip than its cousins.

The crested gecko, unlike the closely related gargoyle gecko , will not regrow its tail once lost. The cells around the base of the tail are brittle, allowing the tail to break away when threatened or caught by a predator. The capillaries to the tail will close almost instantly so there is little to no blood loss. The tails will move independently of the body for 2–5 minutes. The loss of their tail is not problematic, and most adults in the wild do not have their tails.

Unlike most species of gecko, this species is an omnivore, also considered frugivorous, feeding on a variety of insects and fruit. In captivity, they prefer to eat crickets.

Reproduction

Little is known about the wild reproductive behavior of crested geckos, but in captivity they breed readily, with the female laying two eggs which hatch 60–150 days after they are laid. Eggs are generally laid at four week intervals as long as the fat and calcium reserves of the female are still at healthy levels. Crested geckos have two small sacs for calcium on the roof of their mouths. If an egg laying female does not have enough calcium her sac will be depleted, and she can suffer from calcium deficiency. This can lead to a calcium crash where the female appears shaky or wobbly, lethargic, has a lack of appetite, and can even result in death. Eggs laid by a female whose calcium reserves are low occasionally exhibit signs of metabolic bone disease, such as an under bite, or a kinked or wavy tail.

It is undetermined whether heat plays a role in determining the sex of the embryo, as it can with other gecko species. Newly hatched crested geckos will generally not eat until after they shed their skin for the first time, relying on the remains of their yolk sack for nutrition.

A female crested only has to mate with a male once in order to lay 2 eggs every 4–6 weeks for upwards of 8–10 months. Retaining of sperm ensures the eggs the female lays remain fertile throughout her breeding cycle. After those 8–10 months, females in the wild go through a "cooling" cycle, usually prompted by slight temperature changes in winter, which help her regain lost nutrients from egg-laying. In captivity this cooling cycle must be controlled or the female will lay eggs continuously, even to death.