Phelsuma grandis Gray, 1870, is a diurnal arboreal species of day gecko (Phelsuma spp.). These geckos are part of the Phelsuma group, which consists of in excess of 70 species and subspecies. They are commonly referred to as the Madagascar giant day gecko, due to their large size. They are found in areas of tropical and subtropical forest in northern Madagascar. P. grandis feeds on various invertebrates, very small vertebrates, and nectars.
This lizard reaches a total length of 30 centimetres (12 in). The body colour is bright green or, rarely, bluish green. A red stripe extends from the nostril to the eye. On the back there are typically red coloured dots or bars. These red markings are quite variable, and in some cases, completely absent, though the line extending from the nostril to the eye is always present. Some specimens may have small blue spots. Adult specimens may have large sacs on their necks. These are stored calcium sacks. Young individuals of the species often exhibit much more red than their parents, but as time passes, many of the markings fade, to leave those that will stay for the remainder of the gecko's life. The underside of these animals is a creamy white ranging to an eggy yellow. When stressed, the colouration darkens, rendering the whole animal a dark green, and the red markings on the face and back more orange in hue.
This species is widely distributed in northern and northwest Madagascar. It can also be found on some of the off shore islets. There are a few recorded populations of this species also in Florida, and Hawaii, introduced by accident, which seem to like the hot, tropical climate in these locations. It can also be found in Mauritius, mainly in Floreal and in the upper Plain Wilhems, but it is thought that it was introduced there too.
Phelsuma grandis is often found on different trees where it can be seen basking. They also inhabit human dwellings due to the number of appropriate basking spots, and the level of insect activity which these dwellings attract. The climate is rather dry, though heavy rainfalls are quite common. This means that there is a constant level of high humidity throughout the year. When in captivity Phelsuma grandis enjoy bamboo. Most live on the eastern coast of Madagascar.
These day geckos feed on various insects and other invertebrates, and occasionally have been recorded consuming small vertebrates. They also like to lick soft, sweet fruit, pollen and nectar. Geckos in the wild and in captivity have been observed consuming their own young.
Like most Phelsuma species, the males can be quite quarrelsome and territorial and will not accept other males in their neighborhood. They only allow females to enter their territory. In captivity, where the females cannot escape, the males can also sometimes seriously wound a female. In this case the male and female must be separated. Breeding behavior includes, the shaking of the tail or body, vocalizing, and if the female does not accept the male she may turn a darker green. The day geckos may move slowly, but when they are startled they can move very fast. They are known for being very good at escaping their enclosures. Giant day geckos have no eyelids. To keep their eyes clean, they often lick them.
Common Diseases and Disorders
Every once in a while giant day geckos will have a bad shed. The gecko has skin that does not come off the body. This is common and if the skin doesn’t come off after 24 hours an increase in humidity helps loosen up its old skin. Many day geckos have problems shedding the skin of their feet. This is of great importance to the day gecko considering they are arboreal. Another large problem with giant day geckos is metabolic bone disease. This happens when the gecko doesn’t get enough calcium. This can be prevented by making sure your giant day gecko gets plenty of calcium supplements.
The breeding season is between November and the first weeks of May. During this period, the females lay up to 6 pairs of eggs. At a temperature of 28°C, the young will hatch after approximately 60–65 days. The juveniles measure 70 mm and reach sexual maturity after one year.
The species Phelsuma grandis Gray 1870 was elevated from subspecies status (P. madagascariensis grandis) by Raxworthy et al. in 2007, after environmental niche modeling revealed significant and reliable differences between it and other members of the P. madagascariensis-clade. This elevation has since received further molecular support. P. grandis possesses also the junior synonyms Phelsuma madagascariensis venusta Mertens, 1964 and Phelsuma madagascariensis notissima Mertens, 1970 (fide Meier, 1982). The common name, appended to the current accepted name, has been given as Madagascar giant day gecko or variants such as Giant Day Gecko.
Care and maintenance in captivity
These animals should be housed in pairs or singles and need a large, well planted terrarium. When housed alone they should have at least a 10 gallon terrarium. When housed in pairs they should have at least a 29 gallon terrarium. These geckos need many limbs to crawl and bask on. They prefer horizontal and diagonal perches. An excess of vertical perches can result in a condition known among keepers as "tail-flop", wherein the tail hangs perpendicular to the body when the geckos are facing head-down. Giant day geckos need light with both UVA and UVB 5.0 which helps them absorb calcium. The temperature should be between 25 and 28°C, never falling below 17°C, and never exceeding 36°C. The humidity should be maintained between 65 and 75%. These geckos desiccate easily and quickly, so falling below this range can be dangerous. Keeping the geckos at humidity above this range can be done, but levels which are too high can introduce dangerous bacteria quickly. In captivity, these animals can be fed with crickets, wax moths, wax worms, pinky mice, fruit flies, mealworms and houseflies dusted with calcium supplement.
- Glaw, F. and Vences, M. (2007).A Field Guide to the Amphibians and Reptiles of Madagascar. 3rd edition. ISBN 978-3-929449-03-7
- "Giant Day Gecko". Geckoweb. Finding Species. Retrieved 2009-01-27.
- Raxworthy, C.J.; C.M. Ingram; N. Rabibisoa and R.G. Pearson (2007) Applications of Ecological Niche Modeling for Species Delimitation: A Review and Empirical Evaluation Using Day Geckos (Phelsuma) from Madagascar. Systematic Biology 56(6):907-923
- Rocha, S.; H. Rösler; P.-S. Gehring; F. Glaw; D. Posada; D.J. Harris; M. Vences (2010) Phylogenetic systematics of day geckos, genus Phelsuma, based on molecular and morphological data (Squamata: Gekkonidae) Zootaxa 2429:1-28
- Henkel, F.-W. and W. Schmidt (1995) Amphibien und Reptilien Madagaskars, der Maskarenen, Seychellen und Komoren. Ulmer Stuttgart. ISBN 3-8001-7323-9
- McKeown, Sean (1993) The general care and maintenance of day geckos. Advanced Vivarium Systems, Lakeside CA.