On my personal blog I’ve written a short anniversary piece for a conservation tragedy that occurred on this date four years ago. I know many readers arrive here due to an interest in reptiles, so I thought I’d link to it.
Gekko gecko, the bulldog of the gecko world, is one of my favourites and yet another reptile described by Linnaeus in 1758. Two subspecies are now recognized:
G. g. gecko – found from India to Indonesia.
G. g. azhari – found in Bangladesh.
The Tokay has been both prospering and suffering from human activities which makes it an interesting reptile to study. Read the rest of this entry
Moloch horridus – The Thorny Devil – Only terrifying on the outside!
The name is derived from the fact that there are two large horns on the head which give the lizard the appearance of a “devil”. The species name is based on the Canaanite god, Moloch. The choice was inpsired by Milton’s Moloch, a king who was smeared with the blood of human sacrifice. The Latin specific name horridus means rough or jagged.
M. horridus is currently classed as a lone species in its genus, although there is debate over whether there is another species. It was described in 1841 by John Edward Gray after being displayed in London for the first time by John Gould the year before. The Thorny Devil is a moderately-sized lizard, just 4-6 inches long… hardly a terrifying moster! Yet a close-up image displays a horrid monster on the prowl. The Devil is found over most of Western Australia.
In the 1890s, Saville-Kent was the first to keep them in captivity and to thoroughly study their behavor. He discovered that they ate almost nothing but ants, and that they ate a hell of a lot. He also noticed that the Thorny Devil was morphologically extremely similar to many of the Phrynosoma, the North American Horned Lizards. Infact, they were so similar, that Saville-Kent predicted that the Horned Lizards would have a similar diet and he was correct. But, despite appearing superficially similar, it turns out that the Phrynosoma and the Thorny Lizard are only distantly related. But oddly enough, morphologically, the thorny devils are more similar to the Phrynosoma than either is to other members of the lizard fauna who are more closer related phylogenetically (Pianka 1986, 1994). This is a very strong example of convergent evolution. Basically, the Phrynosoma and the Thorny Devil share very similar ecological niches and have experienced similar selection pressures. The bulge on the neck is known as the “second head”. This is not really a second head but when a predator approaches, the Thorny Devil can bow it’s head down to the ground and present the second head in the hopes that if it does get bitten, the real head will hopefully survive the initial attack.
The Thorny Devil specializes in eating ants and eats several species although it has a favorite: Iridomyrmex flavipes. They can eat between 24-45 ants per minute and have been estimated to eat anywhere between 675 and 2500 in a single meal! They lap them up with their quick tongue.
In the dry deserts, the Thorny Lizard gets its water in an unusual way (or at least for us mammals). During the night, dew forms on the Devil’s skin and this moisture is channelled by hygroscopic grooves between the spines (Bentley and Blumer 1962). They carry the water straight to the mouth! Very handy indeed. The Devil can even suck water through its belly, straight into its capillary vessels and transport the water to the mouth… ideal when the rainy days eventually come.
Despite the frightening appearance, the Thorny Devil is rather laid back. It doesn’t move very fast, and anyone who owns chameleons will immediately recognize the movements it makes. It pauses, frozen still, then rocks about in its movements as many species of chameleon do. They can be quite tame indeed and seem to do well in captivity, although they are typically not found outside of Australia as it is now illegal to export lizards from the Australian wild to other countries.
It stays out of the way of everyone, minds its own business, and seems so insignificant, yet it is extraordinarily beautiful and it presents astounding research opportunities on convergent evolution and other areas of biological research. Australians should be proud to have such a delightful little creature endemic to their country.
Rhacodactylus is derived from the Greek words Rhakos meaning “spine” and dactylus meaning “finger”. Ciliatus is Latin for “eyelash”, and named after the Crested Gecko’s magnificent crests over the eyes, and on most specimens, down the back as well.
The Crested Gecko is endemic to New Caledonia, meaning that this island is the only place where there is a natural population of the species. They were first described in 1866 as Correlophus ciliatus by Alphone Guichenot in his article, “Notice sur un nouveau genre de sauriens de la famille des geckotiens du Muséum de Paris”. But for a long time, little research was done and we knew very little about them. Eventually, there were some searches but the species was not found and they were believed to be extinct, banished from the tree of life forever. However, that was until 1994, when a single specimen was found after a tropical storm. The hunt was back on and eventually researchers discovered a small population at the south end of the island. We now know there are two populations, which differ genetically. But still, not much is known about the Crested Gecko. Even their lifespan can only be estimated as the single specimen that was discovered in 1994 is still alive today!
Crested Geckos are small, mostly arboreal lizards. They are omnivorous and will happily snack on a small insect but enjoy nothing more than fruit. They will eat most fruit, but in the wild, they prefer it to be just past ripe and even slightly rotting! Crested Geckos are extremely acrobatic, can hang in the strangest positions and can jump quite unlike anything else considering their size.
The very first time I saw a Crested Gecko, it stayed with me for a few minutes, crawling around and investigating me, and then it leaped several feet back into its terrarium. They jump an astonishing distance and it happens so quick that they appear to teleport from one location to the next. They tend to walk around slowly though.
But this is where the typical character of the Crested Gecko is discovered… Despite being so acrobatic, they are extremely clumsy. The Crested Gecko makes an amusing hunter in that it has no understanding of stealth whatsoever. Crested Geckos are known for their very personable characters and their tendency to be quite “cheeky”.
Cresties share some common traits with many other geckos. For a start, they have no eyelids. They also keep their eyes clean by using their tongue. They also shed like most reptiles although they do not discard the shed skin. They eat it! They dispose of the shed skin entirely by swallowing the whole thing. We could learn a thing or two from the Cresties when it comes to recycling!
A common trait for most geckos is the ability to “stick” to surfaces. Crested Geckos are not sticky as such and their skin is a smooth, velvety skin which is very pleasant to touch. Their feet are used to scale vertical surfaces (and even ceilings!) but they aren’t sticky in the “wet and sticky” sense that the word suggests. Naturalists were always very confused in the past about how geckos scaled surfaces. For a while it was thought by many that they excrete a type of glue but that was proven not to be the case. Others suggested it was some sort of suction but if this was correct then they should stick to glass better than nearly all other surfaces. Geckos such as the Crested Gecko can stick well to glass, but not quite as well as other surfaces. It turns out, that Cresties have sticky pads called lamellae on each of their toes and even on the tip of their tail. These lamellae are made up of thousands of microscopic hairs, which use Van der Waals forces to stick to any surface. This is a truly spectacular design as the gecko has full control and can break the molecular attraction by simply altering the angle of its foot, so it can move effortlessly along vertical surfaces or even upside down!
Crested Geckos communicate both vocally and also visually. Most cresties are pretty quiet, but some are prone to being loudmouthed, especially if a male finds there are some females to impress! The Crested Gecko lives in groups and in captivity is usually kept in groups of 3-5 individuals, with one male and a harem of females. Males tend to fight from time to time and multiple females are required so they aren’t harassed too much by the male. The female has a gestation period of just one month and can retain sperm for up to eight months meaning that having sex once can result in eight clutches, usually with two eggs in each clutch! As well as calling to other geckos, the cresties also make barking sounds and can even imitate crickets!
They come in different colours anyway, but they also have the ability to “fire up” under certain conditions which causes their colours to sharpen and brighten. Their mood often reflects this “firing up” although a good deal of sunlight can cause it as well. My cresties sometimes sleep with one part of their body in the shade and another part in the sun, and afterwards they are partly fired up and look quite odd indeed. But doing odd things is very normal for these guys. There are several variations in their patterns and colours. Some are simply one colour all over, while others are harlequin, having a different colour down their backs. Many of my own are “Flames” with flame-shaped patterns down their sides and some are dalmations, showing off black spots on their body.
Although little is known about the species in the wild, the Crested Gecko has done something rather remarkable. Despite being discovered only in 1994, more Cresties are now being bred in America alone each year than there are living in the wild! Due to the lovable characters, the wacky behavior, the many variations in colour and pattern and their overall beauty, this animal has become a sudden and sensationally popular pet reptile in a very short amount of time. It is believed that within a few decades, and when their genetics are better understood, they may overtake Leopard Geckos as the most popular pet gecko. Only time will tell. In the wild, they are being evaluated for conservation status.