Tail comparison

Tail comparison

by Alex Negro Internationaler Chamäleontag

Chameleons have a unique, movable tail. It is an extension of the spine and can be completely curled up to make the chameleon appear larger. The animals make use of this, for example, when they threaten conspecifics. Due to the shape of the vertebrae, the tail can only be curled downwards – even if Disney somehow didn’t realise this. Tree-dwelling chameleons usually have a tail that is about as long as their body. One exception is Furcifer balteatus, which has proportionally the longest tail. Tree-dwelling chameleons use their tails for gripping when climbing and can easily hang their entire body weight from them. Ground-dwelling chameleons usually only have a short stumpy tail, which is only placed on the ground for stabilisation when walking.

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Photo: Tail of a Parson’s chameleon, photographed by Alex Laube

The panoramic view

The panoramic view

by Alex Negro Internationaler Chamäleontag

Chameleons are known for being able to move their eyes independently of each other. They protrude far from the skull and are completely covered with scaly eyelid skin except for a narrow iris and the pupil. This anatomical peculiarity gives chameleons the effect of a pinhole camera in both eyes, allowing them to see much more clearly. Chameleons can see up to one kilometre (!) away. The focusing speed is around 60 dioptres per second – four times what a human is capable of. Chameleons mainly see colours and little contrast, which makes them practically blind at night. Small oil droplets that accumulate on the cones also provide chameleons with a kind of “built-in sunglasses”. But chameleon eyes can do much more! The chameleon has an incredibly large field of vision of 90° vertically and 180° horizontally. The total field of vision is a fantastic 342°! Only over the back directly behind the head is there a blind spot of 18°, in which a chameleon can see nothing. By comparison, humans only have a paltry 189° field of vision. Chameleons also have very special lenses. The chameleon’s range of accommodation is an incredible 45 dioptres. Humans can accommodate just 15 dioptres when they are young, and even less when they are older. However, it is not known whether the chameleon’s visual acuity decreases with age.

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Foto: Auge eines Pantherchamäleons, fotografiert von Brice Miller, Creative Commons Attribution-Share Alike 4.0 International

The hands and feet of chameleons

The hands and feet of chameleons

by Alex Negro Internationaler Chamäleontag

Chameleons can move perfectly on thin and thick branches. Their modified hands and feet enable them to do this. The bones of both hands and feet are very similar to those of humans. The only difference is that they are divided into small grasping pincers so that the chameleon can hold on to branches better. This makes climbing much easier for them than for us! On the hands, two fingers point outwards and three inwards. On the feet it is the other way round. This situation of “grown together” fingers is called syndactyly. There is a small, pointed claw on each finger and each toe. These claws enable the females to dig effectively so that they can later lay their eggs. This is why the claws of some species become longer than usual during the breeding season.

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Abbildung: aus The Osteology of Reptiles, 1925
Foto: Chamaeleo zeylanicus, fotografiert von Hari K Patibanda, Creative Commons Attribution 2.0 Generic

Eggs or no eggs

by Alex Negro Internationaler Chamäleontag

Chameleons lay eggs! But not all of them. There are two ways in which chameleons reproduce. The vast majority of chameleons actually lay eggs. The eggs are usually white to beige in colour, soft-shelled and small. Egg-laying species include the genera Brookesia, Calumma, Chamaeleo, Furcifer, Kinyongia, Nadzikambia, Palleon, Rhampholeon and Rieppeleon. The smallest eggs are laid by a small, brown ground chameleon from Madagascar, Brookesia nana. They are less than 10 mm in size! The largest eggs are laid by the Parson’s chameleon, Calumma parsonii parsonii, which also comes from Madagascar. Its eggs are several centimetres long at the end of the incredibly long incubation phase of one and a half years. Incidentally, most eggs are laid by the large Meller’s chameleons (Trioceros melleri) and Veiled chameleons (Chamaeleo calyptratus), although the latter are considerably smaller. With heavy feeding in captivity, Veiled chameleon females can produce over 50 eggs, which is an incredible number for such a small animal. The Meller’s chameleon has even been known to lay over 80 eggs.

In contrast, the genera Archaius, Bradypodion and many species of the genus Trioceros are ovoviviparous. This means that these chameleons give birth to live young that are still surrounded by a thin egg membrane at birth. It is assumed that this is an adaptation to cooler temperatures. This is because the egg-bearing chameleons live high up on mountains, where it does not get as warm as further down in the country.

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Video: BBC Earth, Frozen Planet II

Who has the most horns?

Who has the most horns?

by Alex Negro Internationaler Chamäleontag

Many chameleons have horns or other rostral appendages. But who has the most? The regular one is the four-horned chameleon, Trioceros quadricornis. It occurs in Cameroon and Nigeria. The males of this species in particular usually have four real horns on their nose. The subspecies Trioceros quadricornis gracilior can even occasionally have up to six horns – but this horn record is not common. Incidentally, even the females of this species can be horned – this is not the case with many other species.

Incidentally, a distinction is made between true horns and false horns in chameleons. Chameleons with true horns have a bony process on their nose that is covered by a thin layer of keratin. This keratin layer develops from a single scale. These true horns are mainly found in the genus Trioceros. In contrast, false horns also have a bony base, but are covered with normal, scaly skin. False horns are found in many Malagasy chameleons. Finally, there are dermal horns, which consist only of skin. They are soft, flexible and have no bone underneath. These horns are also mainly found in Malagasy chameleons.

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Photo: Jackson’s chameleon, Trioceros jacksonii, also has real horns; Creative Commons Attribution-Share Alike 3.0 Unported, fotografiert von Benjamint444

The oldest chameleon in the World

The oldest chameleon in the World

by Alex Negro Internationaler Chamäleontag

The oldest chameleon in the world comes from Myanmar. More precisely, it was discovered by chance. Myanmar has had commercial amber mines from the Cretaceous period for over a century – probably the only country in the world to do so. The most productive mines of this amber, known as “Burmite”, are located in the Hukawng valley in Kachin in northern Myanmar. These mainly supply the Chinese market, but some are also sold directly to interested private individuals. For years, scientists have repeatedly made highly interesting palaeontological finds among the amber sold.

The chameleon in question, along with other fossils encased in amber, was sold to jewellers who cut the stones into cabochons, a type of gemstone. From there, the pieces were sold to private individuals, including James Zigras and Scott Anderson, private collectors. Scientists were allowed to analyse the ambers and put them in a CT scanner, among other things. It turned out that the little chameleon must have been a juvenile. Almost the entire skeleton and almost the entire skin are preserved. It is only 10.6 mm long and the claws in particular are very well preserved. The overall habitus of the animal suggests that it was a chameleon, only the teeth and the arrangement of the fingers and toes do not quite match today’s chameleons. It is now assumed that this chameleon is over 99 million years old and has been in amber for this long. Of course, it is not a species of chameleon that exists today, but it is a relative. It is called a “protochameleon”, which means it is a precursor to our modern chameleons. In the picture above, the chameleon can be seen at the bottom right, in the amber measuring 1 cm below. This amber is still in a private collection and not in a museum.

…to clarify another question that you have probably asked yourself, but which has not yet been answered: As far as we know, Parson’s Chameleons from Madagascar are the oldest of all chameleons. Individual males that are over 20 years old are known from herpetoculture.

#show your colours #internationalchameleonday #chameleonday #chameleondayMay9 #agchamaeleons

Photo: Various fossils in amber, source: Juan D. Daza, Edward L. Stanley, Philipp Wagner, Aaron M. Bauer, David A. Grimald; Mid-Cretaceous amber fossils illuminate the pastdiversity of tropical lizards, Download

Addendum: Unfortunately, it has since emerged that the little creature in the amber is not a chameleon at all. The oldest chameleon is therefore not from Myanmar after all!

 

Why do chameleons change colour?

Why do chameleons change colour?

by Alex Negro Internationaler Chamäleontag

It is a myth that chameleons can choose their colours according to what they are sitting on. It is also not true that chameleons can adapt to their background and become virtually “invisible”. In fact, chameleons use their ability to change colour to communicate and express their mood. Bright colours are intended to impress opponents. High-contrast patterns in females indicate that they are pregnant. Pale colours show that one opponent is inferior to another, that it is not breeding season or that the chameleon is not doing so well. Incidentally, the proverb about “turning black” fits the chameleon perfectly: when chameleons are in a very bad mood, they actually turn black.

Each chameleon species has a limited colour spectrum at its disposal. The colour change itself is caused by guanine crystals in the skin and takes place unconsciously. And even within the individual species, each chameleon can only take on certain colours. In panther chameleons, for example, where the males are known to be particularly colourful, green skin can turn yellow or orange when excited, blue skin can even turn white, but red skin can only change in intensity.

And then there are also terrestrial leaf chameleons, which are not “typically colourful chameleons”. But they are just as colourful as chameleons, only less well known. Due to their habitat on the ground, they mainly wear brown and beige colours.

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Pictures:
Panther chameleon in a calm (left) and excited state (right), source: Jérémie Teyssier, Suzanne V. Saenko, Dirk van der Marel, Michel C. Milinkovitch, Photonic crystals cause active colour change in chameleons, Download
Chamaeleo zeylanicus in different colours throughout the day, photographed by Dr. Raju Kasambe, Creative Commons Attribution-Share Alike 4.0 International
Bradypodion damaranum, Bradypodion transvaalense and Bradypodium caffrum, Colouration in dominant (left) and inferior (right) males, source: Devi Stuart-Fox & Adnan Moussalli, Selection for Social Signalling drives the evolution of chameleon colour change, Download

 

What do chameleons eat?

What do chameleons eat?

by Alex Negro Internationaler Chamäleontag

Most chameleons are insectivorous, i.e. they feed on insects, arachnids, arthropods and other small animals. Depending on their size, their diet can range from flies, moths, wasps, butterflies and grasshoppers to praying mantises or spiders. Small, ground-dwelling chameleons in particular also feed on woodlice, springtails and aphids. The largest chameleons, on the other hand, do not spurn the occasional small bird or gecko. As many travellers and chameleon keepers have observed, chameleons are opportunists when it comes to food. If a young chameleon is nearby and it would fit well in their mouth, they will sometimes shoot a much smaller fellow chameleon off a branch and eat it. Fortunately, this is not the rule. A few chameleon species are also known to eat plant leaves from time to time. For centuries, chameleons were thought to be pure ambush hunters. In fact, this is not quite true. They are so-called “cruise foragers”, that don’t just wait in one place for food, but go hunting at a very leisurely pace.

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Picture: Chamaeleo chamaeleon schießt ein Insekt in Kapıçam National Park, Türkei; Creative Commons Attribution-Share Alike 4.0 International, fotografiert von Mkrc85

The largest chameleon

The largest chameleon

by Alex Negro Internationaler Chamäleontag

The largest chameleon in the world – well, actually several species are fighting for the title. There are three contenders: the Meller’s chameleon (Trioceros melleri) from mainland Africa, the Parson’s Chameleon (Calumma parsonii parsonii) from Madagascar and the Madagascar giant chameleon (Furcifer oustaleti).

The Meller’s chameleon is found in the mountains of Tanzania, northern Mozambique and Malawi. The main distribution area is known to be Mount Zomba. The largest chameleon of this species measured to date is said to have measured 76 cm from the tip of its nose to the tip of its tail and weighed 600 g. The Parson’s chameleon, on the other hand, is found in various places on the central and southern east coast of Madagascar. Here, the largest chameleon measured so far is said to have been 72 cm long, but there are even measurements of over 700 g in weight. The Parson’s Chameleon is therefore definitely heavier, and the size of some animals comes close to that of the Meller’s chameleon. That leaves the Madagascar Giant Chameleon. It reaches almost 70 cm and, despite its sometimes impressive size, it almost always weighs less than 500 g. So despite its name, it will probably have to make do with third place.

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Pictures:
Trioceros melleri,  Creative Commons Attribution 4.0 International, photographed by John Lyakurwa
Calumma parsonii parsonii, Creative Commons Attribution-Share Alike 4.0 International, photographed by von Jialiang Gao
Furcifer oustaleti, Creative Commons Attribution-Share Alike 4.0 International, photographed by Sharp Photography

The smallest chameleon of the Earth

by Alex Negro Internationaler Chamäleontag

The world’s smallest chameleon is also the world’s smallest amniote. It is called Brookesia nana – Nano chameleon – and was only discovered in 2021. Given its size, this is hardly surprising – it is only 22 mm long! The male is even a little smaller than the female, which at 29 mm in total length is no giant either. Its home is the island of Madagascar in the Indian Ocean, more precisely in the Sorata Massif in northern Madagascar. It lives in layers of foliage at the foot of large trees. There is another exciting feature: in relation to its body size, the male of this species has incredibly large hemipenes! Yes, chameleons have two penes instead of a single penis – handy if one breaks. But in the nano chameleon, the hemipenes make up 18.5% of the total body length. In humans, that would be the same as if the penis of a 1.80 metre tall man were 33 cm long.

But back to the nano chameleon itself. Despite its tiny size, like many other chameleon species it reproduces by laying eggs in the foliage. These hatch into even tinier young, which feed on the smallest micro-insects on the ground. Overall, however, the tiny creatures are likely to have a relatively hard time in the rainforest, as even any spider is bigger than them and certainly sees a small chameleon as a welcome change on the menu, but in fact the main threat to the small chameleons is humans. The nano-chameleon was probably already threatened with extinction before it was discovered.

The discovery was a pretty big deal at the time. It was reported everywhere, for example in Die Welt, auf National Geographic, bei Scinexx, im GoodNews Magazin oder bei der Frankfurter Allgemeine Zeitung. You can download the original publication for free here. And what we still don’t know: Is there perhaps even a smaller chameleon? After Brookesia minima, Brookesia micra and Brookesia nana, the only thing missing is Brookesia pika. Madagascar has already had a few surprises in store… maybe this one too?

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Video: EndangeREX, Timon Glaw