Ultrasound of the urogenital tract in chameleons

Ultrasound of the urogenital tract in chameleons

by Alex Negro Tiermedizin Science

In recent years, initial studies have been conducted on imaging in the diagnosis of diseases specifically in chameleons. A further study by veterinarians at the University of Leipzig (Germany) now presents additional comparative data on the urogenital tract of chameleons.

They examined the kidneys, bladder and reproductive organs of 42 lizards brought to the university hospital by private owners using ultrasound. Among the patients were seven Chamaeleo calyptratus and five Furcifer pardalis. Of these 12 chameleons, six were male and six were female. All organs were measured, described and sample images were saved.

Unfortunately, the sex organs of none of the female chameleons could be assessed for the study, as they were either pathologically altered or had already been removed during previous surgery. The most suitable location for coupling the ultrasound probe to the kidneys of the chameleons was found to be approximately one centimetre in front of the hip. The postpelvic portion of the kidneys was always smaller than the prepelvic portion. The kidneys of all male chameleons showed heterogeneous stripes, while the kidneys of the females were always homogeneous. This striping is probably due to sexual segments in the kidneys of males. The kidney tissue was isoechogenic to muscle tissue and more hypoechoic than adipose tissue. The testes of the male chameleons were located in the posterior third of the coelomic cavity, directly below the spine and in front of the kidneys. The right testicle was slightly further forward than the left. The capsule was hyperechoic in all males, while the testicular structure was always homogeneous. The study also provides average measurements of the kidneys and testicles of Yemen and panther chameleons.

The data largely correspond to the data already compiled by Aßmann in 2015 on ultrasound of the urogenital tract of chameleons. Only the kidney length differed significantly (longer) from previous studies.

Comparative sonographic studies of the urogenital tract of lizards
Nils B. Klützow, Volker Schmidt
Veterinary Radiology & Ultrasound 2025, 66:e70075
DOI: 10.1111/vru.70075
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Gene evolution in chameleon teeth

Gene evolution in chameleon teeth

by Alex Negro Science

Chameleons have acrodont teeth, which means that their teeth are directly attached to the bone. Mammals, on the other hand, have so-called alveoli in which the teeth are seated. Scientists from Michigan (USA) have now investigated the genetic evolutionary development of tooth structures by comparing mammals with acrodont reptiles.

To do this, they compared the genomes of 24 acrodont reptiles and 12 mammal species. The acrodont reptiles included the chameleon species Furcifer pardalis, Trioceros harennae and Chamaeleo calyptratus, as well as chameleons of the genera Chamaeleo, Bradypodion and Trioceros that were not identified at the species level. The genes for amino acids, from which certain proteins in tooth enamel are built, were compared using various calculations and analyses.

The results showed that the loss of tooth replacement in acrodont reptiles did indeed lead to changes in the genes responsible for tooth enamel formation.

Reduction of tooth replacement disproportionately affects the evolution of enamel matrix proteins
John Abramyan, Gengxin Li, Hannah Khansa
Journal of Molecular Evolution 93, 2025: 494-510.
DOI: 10.1007/s00239-025-10258-4
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Photo: Specimen of a panther chameleon skull with acrodont teeth, photographed by Alex Negro

…and they do adapt to their surroundings!

…and they do adapt to their surroundings!

by Alex Negro Science

The headline isn’t quite right, but it’s close. Scientists from the United Kingdom have recently proven that flap-necked chameleons do indeed adapt their colouring to their surroundings to a certain extent.

To this end, eight subadult Chamaeleo dilepis, which had previously been imported from Tanzania, were subjected to several experiments. The chameleons were placed in a small terrarium sitting on horizontal bars and exposed to different backgrounds: in the first experiment, the backgrounds were yellow, yellow-green, orange and blue-green; in the second experiment, the backgrounds were black and white. And in the third experiment, the backgrounds were decorated with yellow, yellow-green, black or white patterns in different scales (the pattern was originally taken from photos of blackberry bushes from the chameleons’ habitat). A terrarium with a grey background was used as a ‘neutral space’ before the experiments. The animals were photographed repeatedly for 21 minutes during each experiment.

On the yellow background, the chameleons without the predator decoy changed colour most quickly. There was no difference in the speed of colour change between yellow and orange, nor between yellow-green and blue-green backgrounds. The longer the chameleons sat in front of the orange background, the more they adapted to it.

When the chameleons sat on black backgrounds, their colouring also became significantly darker than on grey or white backgrounds. In experiments with differently patterned backgrounds, the scientists found that the chameleons reduced their own colour pattern on green or yellow backgrounds, but hardly at all on white or black patterns – this suggests that the animals are better protected in their natural habitat, especially in green/yellow grass, than on black or white backgrounds.

Of course, the flap-necked chameleons were not able to take on the exact colour of the background like an octopus – this myth remains just that – a myth. However, it would certainly be interesting to know if and when chameleons change their colouring for reasons of communication, camouflage or thermoregulation. So there is still plenty of room for further research.

Flap-necked chameleons change colour to match their background
Tom major, Alexia C.M. Hesten, Jan Stipala, Michael A. Cant, Martin Stevens, Jolyon Triscianko
Biology Letters 21, 2025: 20250134
DOI: 10.1098/rsbl.2025.0134

Comparisons between dwarf chameleons in South Africa

Comparisons between dwarf chameleons in South Africa

by Alex Negro Science

South African scientists have recently been investigating whether three closely related Bradypodion lineages in the Eastern Cape Province of South Africa have evolved differently due to their different habitats or whether other causes are responsible.

The scientists are studying the two species Bradypodion ventrale from the Nama Karoo and Bradypodion taeniabronchium from the Elandsberg and Tsitsikamma Mountains and the fynbos of Thyspunt and Honeyville, as well as a population of dwarf chameleons from the fynbos of the Groot Winterhoek Mountains that has not yet been described as a separate species. The latter are often referred to as Bradypodion sp. ‘groendal’ because they occur in the Groendal Nature Reserve, among other places.

At night, chameleons were searched for using flashlights and the naked eye. Adult chameleons with a body length (SVL) of more than 36 mm were taken away overnight to be released back at the site where they were found the next day. All animals were measured accurately. Tissue samples were taken from the tip of the tail. In addition, the thickness and height of the branches on which the chameleons were found were measured. Further branch thicknesses were recorded along three 100 m long transects in each population. The data collected was statistically evaluated and the tissue samples were genetically examined.

A total of 232 chameleons were sampled for the study. Bradypodion taeniabronchium had significantly smaller head features than the other two species, but larger hands and feet. Bradypodion ventrale was larger overall than the others, but had longer limbs. Bradypodion taeniabronchium used the widest branches (average diameter 2.83 mm), but also the lowest (average height 82 cm above the ground). Bradypodion ventrale, on the other hand, used the thinnest branches (average diameter 1.52 mm), but the highest (average just under 93 cm above the ground).

The researchers found that all three populations of dwarf chameleons showed increased external similarity (convergence) when they occurred in the same habitats and less similarity (divergence) when they occurred in different habitats. The dwarf chameleons preferred certain branch thicknesses depending on their population, even though other branches were also available in their habitat. Finally, the authors point out that all the evidence available so far suggests that the as yet undescribed dwarf chameleons of the Groendal Nature Reserve represent a separate species.

Ecological factors promote convergent evolution and ecological speciation in dwarf chameleons (Bradypodion)
Krystal A. Tolley, Devon C. Main, Keith M. Dube, Bettine Jansen van Vuuren, Jessica M. da Silva
Zoosystematics and Evolution 101(3) 2025: 1227-1247
DOI: 10.3897/zse.101.151926

Photo: Bradypodion ventrale, from the publication cited

UV fluorescence in dwarf chameleons

UV fluorescence in dwarf chameleons

by Alex Negro Science

Chameleons have window-like, translucent scales over certain bony processes, especially on the head. If the bone is illuminated with UV light at these points, the areas light up. It has previously been assumed that this UV fluorescence or the fluorescent tubercles are used for intra-species communication. South African scientists have now investigated this further in dwarf chameleons.

Five Bradypodion species in different habitats (fynbos, forest, bushland) were studied.

If the fluorescent tubercles are used for communication between males and females during reproduction, one would have to assume that their number differs greatly between males and females. Chameleons that live in a dense forest should also have more of them than animals in open terrain that is easy for predators to see.

The result of the study is quite astonishing: the larger sex of each of the different dwarf chameleon species had the higher number of fluorescent tubercles. Bradypodion of the same size, on the other hand, always had approximately the same number of fluorescent tubercles on their heads. The different habitats did not appear to have any influence on the number of fluorescent tubercles. There was also no difference between habitats heavily influenced by humans, such as gardens, and near-natural, unspoilt landscapes.

The authors conclude that the fluorescent bone tubercles in South African dwarf chameleons are probably not used for communication. It remains to be seen whether this is also the case in other chameleon species.

Body size, not habitat or sex, best explains the extent of ultraviolet fluorescence in African dwarf chameleons (Bradypodion)
Jody M. Barends, Wade K. Stanton-Jones, Graham J. Alexander, Krystal A. Tolley
Journal of Zoology
DOI: 10.1111/jzo.70032

Flap-necked chameleons in Cabinda (Angola)

Flap-necked chameleons in Cabinda (Angola)

by Alex Negro Verbreitung Science

The province of Cabinda, a 7064 km² area belonging to Angola between the Democratic Republic of the Congo and the Republic of the Congo, is one of the least explored herpetological areas in Africa. The enclave is located around 50 kilometres north of the rest of Angola, directly on the Atlantic coast. Both its enclave status and the difficult accessibility of the existing forest areas have contributed to the fact that little information exists on the local herpetofauna. The Mayombe National Park makes up around a third of Cabinda’s territory. Mayombe is divided into a higher part of the park with rainforest between 500 and 900 metres and a lower part between the Inhuca and Chiloango rivers. This is followed by a coastal plain with valleys and drier vegetation directly on the coast.

During ten expeditions between 2018 and 2024, reptiles and amphibians were searched for on a daily basis. A total of 17 different locations were covered, 10 of which were within Mayombe National Park. Photos were taken of all animals and samples were taken to enable genetic identification.

Chamaeleo dilepis, which is widespread in Angola, was discovered in Mbongo Zimune in Mayombe National Park near the river in a plantation of introduced bamboo. The bamboo plantations are located at around 324 metres above sea level. The species was also found in Nganzi at 107 m in the valleys, where it is more common according to other literature. In the drier coastal areas, where Chamaeleo dilepis is also said to occur frequently, no chameleon could be detected in the present study.

A total of 76 different species were recorded, including 48 amphibian and 28 reptile species. 33 amphibian and reptile species mentioned in earlier literature could not be found again.

Filling the gaps: herpetological checklist of Mayombe National Park and Cabinda Province (Angola) shed light on one of the most unexplored corners of tropical Central Africa
Javier Lobón-Rovira, Ninda L. Baptista, Tyron Clark, Luke Verburgt, Gregory F.M. Jongsma, Werner Conradie, Luis Verissimo, Pedro Vaz Pinto
African Journal of Herpetology 74(1): 1-59
DOI: 10.1080/21564574.2024.2421007

Chameleons in Andrafiamena-Andavakoera (Madagascar)

Chameleons in Andrafiamena-Andavakoera (Madagascar)

by Alex Negro Verbreitung Science

The north of Madagascar is a treasure trove of biodiversity – this has long been known. Nevertheless, even in the 21st century, many areas of the island are still little explored. A group of Malagasy and US biologists has now presented a new overview study that focuses on one such area.

The Andrafiamena-Andavakoera Protected Area (Paysage Harmonieux Protége d’Andrafiamena-Andavakoera) is located in the north of Madagascar, right between the Ankarana National Park and the Analamerana Protected Area. It is managed by the NGO Fanamby and consists of three isolated dry forests called Binara, Antsahabe and Andrafiamena.

During the transition from the dry to the wet season, observations were made by day and night with the naked eye along designated transects and pitfall traps were dug into the ground along three transect lines. In addition, possible reptile refuges, for example under dead wood, were examined and frog calls were recorded.

A total of 13 amphibian and 39 reptile species were recorded in the three forests. Three species of chameleons were frequently found in all three dry forests: Brookesia stumpffi in the deciduous layer, Furcifer pardalis and Furcifer petteri on trees and shrubs. Surprisingly, the most common chameleon species in Madagascar, Furcifer oustaleti, was only found in Andrafiamena during the study period, but not in Binara and Antsahabe. Brookesia stumpffi was always found on the ground or sleeping on young plants below 1 m height. Furcifer petteri and Furcifer pardalis tended to be found in the middle or upper part of the trees. The authors cite humans and the associated destruction of habitat as a possible threat to the protected area.

Herpetofaunal diversity in northern Madagascar: The Andrafiamena-Andavakoera protected area.
Fandresena Rakotoarimalala, Arianna Kuhn, Achille P. Raselimanana, Sara Ruane
Malagasy Nature 19, 2025: 160-174
DOI: not available

Photo: Male Furcifer petteri in Madagascar, photographed by Alex Negro

Chameleons in St. Luce (Madagascar)

Chameleons in St. Luce (Madagascar)

by Alex Negro Verbreitung Science

The St. Luce reserve is located in the south-east of Madagascar, just 34 km north of the city of Tolagnaro (Fort Dauphin). The protected area includes beaches and rocky cliffs on the coast of the Indian Ocean, lowland rainforest, marshland, savannah-like plains, rivers and lagoons. The remaining rainforest is broken up into many small fragments. There is also a very large rare earth mining project in the area. 12 of the 17 forest fragments of St. Luce are affected by the mining work. A group of scientists has now studied the herpetofauna of the area in more detail.

Over a period of two years, reptiles and amphibians were searched for and captured in St. Luce. The searches were carried out with the naked eye along existing transects. In addition, ground traps were used for two weeks along four 100 m long lines. Five artificial shelters and five corrugated sheets were laid out at a total of 12 locations to check for animals after a certain period of time. Samples of tail tips and toes were taken and measurements taken, after which the animals were released back to their original locations. The species were identified by genetic analysis.

Of 17 rainforest fragments in St. Luce, the scientists found only one intact and another intact but heavily fragmented. All other forest fragments were found with clear signs of habitat destruction. A total of 22 amphibian and 54 reptile species were found. Four species of chameleons were among the reptiles: Palleon sp. aff. Nasus, Calumma tjiasmantoi, Furcifer major and Furcifer verrucosus. All four chameleon species occurred exclusively in the remaining intact or intact areas of the Angalavinaky, Ambandrika and Andranangy/Amboronteny/Agnalaro forests. In the forests already destroyed by the mine, no chameleons were found at all. Of the 76 amphibian and reptile species found, 13 were candidate species, which are presumably undescribed new species.

The authors point out that, according to the present study, the diversity of the herpetofauna in St. Luce is significantly greater than previously assumed. They suggest that several forest fragments should be included in the “Mining Avoidance Zones”, i.e. areas where rare earths should not be searched for, and that the protection status should be increased.

A littoral treasure trove: a comprehensive assessment of the herpetofauna of Sainte Luce, southeastern Madagascar
Sam Hyde Roberts, Marco Sannolo, Hoby Tsimijaly Longosoa, Ryan Clark, Leo Jhaveri, Gonçalo M. Rosa, Walter Cocca, Franco Andreone, Angelica Crottini
Systematics and Biodiversity 23(1): 2513472
DOI: 10.1080/14772000.2025.2513472

Photos: Chameleons found in St. Luce from the aforementioned publication

Frugivory in Furcifer oustaleti

Frugivory in Furcifer oustaleti

by Alex Negro Beobachtungen Science

Frugivory, the eating of fruit, is only known from a few chameleon species. These are mainly isolated observations. Japanese scientists have recently investigated the extent to which fruit-eating chameleons could contribute to the spread of plant seeds.

The study was carried out in the Ankarafantsika National Park in western Madagascar. Three species of reptiles in Madagascar were observed during two rainy seasons and their droppings were examined: The Madagascar giant chameleon Furcifer oustaleti, the Madagascar iguana Oplurus cuvieri and the plated lizard Zonosaurus laticaudatus. The reptiles were observed during the day and filmed or photographed while feeding on fruit and then captured. Chameleons were mainly caught at night. Fruits with seeds were collected for identification from plants on which reptiles of the three species mentioned had been feeding. All captured reptiles were kept in net containers for 6 days until faeces were deposited. The animals were then microchipped and released back into their habitats. The scientists then attempted to sow plant seeds obtained from the animals’ excrement.

A total of 89 chameleons, 254 Madagascar iguanas and 38 shield lizards were captured for the study. 24.7% of the Furcifer oustaleti sampled had plant seeds in their feces, compared to 20.1% of the iguanas and 15.8% of the tortoiseshell lizards. The observations showed that the chameleons and the plated lizards ate fruit from at least eight different plants, while the iguanas ate from as many as 18 different plant species. Some of the plant seeds obtained from the feces had germination rates of over 50%.

During the observation period in Ankarafantsika, Furcifer oustaleti only ate red, black or brown fruits with a maximum diameter of one centimeter. Green or larger fruits were always left on the plants. The fruits were usually first tapped with the tongue before they were actually eaten. Sometimes the fruits were also shot with the tongue. Fruits of Grangeria porosa, Terminalia boivinii, Trilepisium madagascariense, Antidesma madagascariense, Bridelia perviellana, Phyllanthus casticum, Chassalia princei and Doratoxylon chouxii were ingested by Furcifer oustaleti. Fruits were recorded from both sexes of chameleons and regardless of body size in each of the observation months.

The authors conclude that all three reptile species could contribute to the spread of plants in their habitat. Until now, the brown maki (Eulemur fulvus) in Ankarafantsika was primarily thought to be a seed disperser. Now the considerations should probably be extended to reptiles and their role in the forest ecosystem – even if the proportion of seeds in their droppings is significantly lower than that of lemurs.

Frugivory by three species of lizards in Madagascar: Implication for their ecological roles as seed disperser
Ryobu Fukuyama, Wataru Noyori, Shuichiro Tagane, Shouta Iyoda, Hiroki Sato
Biotropica 57(4): e70052
DOI: 10.1111/btp.70052

Photo: Furcifer oustaleti eating fruit, image from the above-mentioned publication

First vertebrate with annual allochrony: Chamaeleo chamaeleon musae

First vertebrate with annual allochrony: Chamaeleo chamaeleon musae

by Alex Negro Science

Allochrony describes the phenomenon that two or more populations of a species have different reproductive cycles over time, even though they occur in the same habitat. In so-called annual allochrony, the populations reproduce at different times of the year. Allochrony is known from many different species, such as insects and corals, which reproduce at different times of the day. Annual allochrony, on the other hand, is extremely rare and has never been demonstrated in vertebrates. Two scientists from Israel have now discovered this phenomenon in chameleons for the first time.

Between 2009 and 2021, they studied the Chamaeleo chamaeleon musae populations in the Holot Mash’abim Nature Reserve in Israel on two nights per month. The reserve is located in the northwestern part of the Negev desert. During the study, the chameleons were searched for from a slow-moving car with flashlights along a 4 km long path. Animals found were measured, sexed, location recorded and claws clipped in a specific sequence for identification. All animals were released at their location within less than 20 minutes. In order to estimate the age of the animals, the time periods between the recovery of previously marked animals were used, as well as an algorithm developed using XGBoost. The chameleons could thus be assigned to the age classes < 1 year, 1-2 years and > 2 years. All data was statistically analyzed.

The astonishing results show that Chamaeleo chamaeleon musae probably occurs in two populations in the Negev desert, separated by annual allochrony. In odd-numbered years, one population of chameleons hatches in September. These animals survive until about November of the following year. In even-numbered years, the second population of chameleons hatches, whose animals also live until November of the following year. The lifespans of the two populations only overlap for a short period of time, when one population is hatching and the already adult animals of the other population are laying eggs. The reproductive Chamaeleo chamaeleon musae of both populations therefore do not overlap or only very rarely due to very few, longer-lived individuals.

The scientists were able to find a total of 1289 chameleons < 1 year old, 231 aged 1 to 2 years and 27 chameleons > 2 years old. Of these, 713 Chamaeleo chamaeleon musae had already been caught for the first time as juveniles, so that their age could be estimated very well. Only 9 of these were rediscovered between 1 and 2 years of age. The survival rate of the hatchlings until their first breeding season was extremely low. In odd-numbered years it was 1%, in even-numbered years 2.5%. Even fewer chameleons survived the first year, at 0.46% and 1.3%. Both populations of Chamaeleo chamaeleon musae were highest in the first and second month of hatching and then declined rapidly. Male chameleons were slightly less likely to survive the first breeding season than females, but overall survival rates were similar for both sexes. In each year of observation, the first hatchlings emerged between mid-September and mid-October, at the end of the hot season. During the cooler and wetter season from December to March, significantly fewer chameleons, most of them juveniles, were found.

This very exciting study naturally raises many more questions. There are several short-lived chameleons, but the entire life cycle of only a few, such as Furcifer labordi, is even known or has been studied. It is possible that there are even more vertebrates with annual allochrony among the chameleons – this still needs to be researched!

First evidence of yearly allochrony in a terrestrial vertebrate: A case study of an annual chameleon
Liran Sagi, Amos Bouskila
Ecology 106(6), 2025: e70144
DOI: 10.1002/ecy.70144

Picture: Chamaeleo chamaeleon, photographed by Markus Grimm