Table of contents for November 2023 in Practical Reptile Keeping

A study led by scientists from Griffith University in Queensland, Australia, on the influence of pollution on the sex ratio of clutches of green sea turtles (Chelonia mydas) has found that it may compound the female-biasing influence of rising global temperatures. It has emerged that exposure to heavy metals, in the guise of cadmium and antimony, as well as certain organic contaminants accumulated by the mother and transferred to her eggs, may cause embryos to become feminised as a result. Unfortunately, green sea populations are already at risk because of a lack of male hatchlings. The reality of the situation “Green sea turtles are listed as endangered on the IUCN Red List of Threatened Species, and at risk of extinction due to poaching, collisions with boats, habitat destruction, and accidental…

A new species of mosasaur—large, carnivorous aquatic lizards that lived during the late Cretaceous Period—has characteristic features that place it between two mosasaurs that are already relatively well-studied, bringing researchers closer to understanding how different groups of mosasaurs are related to each other. Discovered in the U.S. The new species, now known to science as Jormungandr walhallaensis, has been named after Jormungandr, a sea serpent of Norse mythology, and the small North Dakota city, Walhalla, near to where the fossil was found. “If you put flippers on a Komodo dragon and made it really big, that's basically what this new mosasaur would have looked like,” explains Amelia Zietlow, who is based at the American Museum of Natural History's Richard Gilder Graduate School. The fossil on which the study is based…

The genus Antaresia consists of a group of four species of python whose distribution is centred predominantly in Australia, although the spotted python (A. maculosa) itself has also been reported to exist in southern Papua New Guinea. Stimson's python (A.stimsoni), another member of the group, is further divided into two subspecies by the majority of herpetologists, although some controversy does exist about this division. All these pythons are relatively small, making them quite manageable. The genus even includes the smallest python species in the world, the anthill or pygmy python (A. perthensis). Spotted pythons are the largest of the Antaresia species, but are still incredibly small when considered alongside most other pythons, seldom exceeding 107cm (3.5ft) in length. Care notes There are two distinct “types” of spotted pythons available in…

This remarkable lizard occurs further north than any other species, with its distribution extending to Scandinavia and into the Arctic Circle, where the winters are bitterly cold. Yet it is well-adapted to live in these harsh surroundings. It manages to find relatively warm localities underground, where it can spend the winter hibernating, emerging to feed on midges and other bugs in the spring. Viviparous lizards can even survive being frozen for a limited period, thanks to their unique physiology. Their breeding habits are different from those of many other lizards, as females generally give birth to live young, which explains their common name. This reproductive technique shortens the development period of their offspring, increasing the chances of breeding success. The range of the viviparous lizard is very wide, however, and…

Infectious diseases need to be an increasingly significant consideration these days, when it comes to reptile husbandry. This is not – as far as is known – because there has been an upsurge in the microbes responsible for such illnesses, but simply because we are more aware of the dangers. We now have a much better understanding of viruses to which reptiles are susceptible, as the result of recent research in this area. Be patient! Bacteria, fungi and viruses can all cause non-parasitic infections in reptiles. Yet there is an important distinction to be made between those infections that arise when an individual is already ill and immunocompromised, as is the case with the mouth infection known as stomatitis that is most likely to be seen in tortoises emerging from…

FEATURE | LIZARD TAIL INJURIES Tail injuries are most likely to arise in the flightier pet lizards, especially iguanas and water dragons, and Iggy the green iguana was no exception. Initially, he seemed fairly social but as he got older, he became more feisty when disturbed and would often engage in ‘tail whipping’ thrashing his tail around wildly. This is a sign of agitation that often precedes more aggressive behaviour. Unfortunately, the tip of the tail can be easily traumatised in these situations, leading to fractures or dislocations and this then results in a loss of the blood supply to its tip. In the wild, the affected length of tail will often just fall off once the blood supply has ceased, creating what is sometimes described as a ‘stub-tailed’ individual,…

Unlike their relatives, individuals of the brilliant-thighed dart frog (Allobates femoralis) are not poisonous but are simply captivating due to their different behavioural profiles. They successfully reproduce with different strategies, depending on whether they are bold, aggressive or explorative by nature, in the case of both sexes. In addition, certain character traits are already present in this species at the tadpole stage, as has been revealed in new studies carried out by the University of Bern in Switzerland. These particular amphibians are common in the rainforests of the Amazon region in South America. While their highly poisonous relatives, such as frogs of the genus Phyllobates, are frequently used by indigenous people of Colombia to extract toxins by rubbing the skin onto arrowheads for the purposes of hunting and fighting, this…

In the geological past, several groups of crocodiles evolved an appearance that was adapted to marine life. However, the extent of these adaptations and their evolutionary trajectories has remained unknown, up until now. An exhaustive study of their body shape or morphology by a scientific team from the Evolution & Diversity Dynamics Lab (EDDyLab) at the University of Liège in Belgium has now finally shed light on the evolutionary mechanisms at work, thanks to three-dimensional reconstructions. True marine species Contrary to what the relatively few types of modern crocodilian (which number less than 30 species) might suggest, the crocodile group was much larger and far more highly diversified in the past, with herbivorous, arboreal, and even totally marine species all having existed in the past. Two groups, known as the…

The fossil of an ancient marine reptile dating back 170 million years has finally been identified as the world's oldestknown pliosaur. It was part of a group of ocean-dwelling reptiles which were closely related to the famous long-necked plesiosaurs, and were seemingly highly predatory by nature. The findings are rare and add new knowledge to the evolution of plesiosaurs. The fossilised remains themselves were actually found 40 years ago in northeastern France. The member of an entirely new genus An international team of palaeontologists from the Naturkunde-Museum Bielefeld in Germany, the Institute of Paleobiology of the Polish Academy of Sciences in Warsaw, Poland, the Natural History Museum in Luxembourg and The Museum of Evolution at Uppsala University in Sweden have now analysed them and identified them as belonging to a…

FEATURE | DESERT TORTOISES Tim Shields doesn't strike you as a natural rebel. He's a biologist who has spent more than a quarter of a century studying the Mojave desert tortoise, walking some 40,250 km (25,000 miles) in pursuit of his target species and monitoring its decline down the years. Sadly, this is what most field biologists tend to do these days over the course of their careers. But then, in Tim's case, frustrated by what he was observing, he switched from being a detached scientist and transformed into a committed activist, seeking to do something positive that might curb the huge fall in the tortoise population that he had witnessed. Mounting issues The difficulties faced by this species are typical of those encountered by many others worldwide, with human…

These snakes are one of five species that form the Candoia genus of south-east Asian boas. They have acquired a reputation for being difficult to breed, yet if you follow their requirements, then you should be successful. Over recent years, I have bred probably many of these snakes as they are a particular favourite of mine, and I now have one of largest collections of them outside their native range in New Guinea. Part of my aim in this article is to cover the different phases, morphs and locales of these snakes. Many people are presently unaware of the huge scope that exists when it comes to naturally occurring colour variants in this species, some of which are very striking. Phases All the species forming this genus are polymorphic. Polymorphism…

The gigantic, slimy salamanders known as hellbenders (Cryptobranchus alleganiensis), which were once the apex predators of many freshwater streams in eastern and central parts of the U.S. have been in decline for decades. Their populations were constantly shrinking, but no one knew why for sure. But William Hopkins, professor in the Department of Fish and Wildlife Conservation and director of the Global Change Center at Virginia Tech, suspected the hellbenders’ plight had connections with environmental changes engineered by humans. Hellbender males select nesting sites on stream bottoms and guard the eggs laid there by females — although occasionally they may eat the eggs, consuming them before they ever get to hatch. A study that Hopkins led, conducted by eight years of snorkelling in ice-cold streams in southwestern Virginia, found that…

New research led by a Florida State University team of scientists shows that potential adaptive responses by sea turtles, such as shifting the timing of when they nest, may not be enough to counteract the projected impacts from climate change on the breeding success of these marine reptiles. Warmer temperatures cause lower hatchling success and a greater percentage of female turtles, both of which can disrupt the viability of a species in the longer term. Sand temperatures at sea turtle nesting sites globally are projected to increase by about 0.6°C (1.1°F) to about 4.2°C (7.6°F) by 2100. A broad study In order to examine how sea turtles might cope with higher temperatures, researchers, led by Department of Earth, Ocean and Atmospheric Science associate professor Mariana Fuentes, gathered data from 24…

Heading north As I crossed the newly-constructed Kazungula bridge spanning the Zambezi (which is the fourth longest river in Africa), travelling from Botswana into Zambia, I wondered what it would be like? There is always a slight sense of nervousness when you set out on a journey of this type, combined with excitement. Three months to explore a country is just not long enough though, so I'd have to try and cram as much in as I possibly could in the available time. Sixty kilometres (37 miles) from the border, I arrived in the town of Livingstone; so-called after Dr David Livingstone who was the first white person to see the famous Victoria Falls, which he named after Queen Victoria. I booked into the Maramba River lodge, which is situated…

As their name suggests, invertebrates represent a group of creatures that lack a vertebral column and indeed, any bones in their bodies. Some, such as corals and starfish live in the marine environment, whereas the coverage that follows here concentrates exclusively on terrestrial members of the group that are popular vivarium occupants. Huge numbers These are species belonging to the phyla Mollusca and Arthropoda. The molluscs, as members of the first group are known, are very widely distributed, occurring in the sea, as well as on land and in freshwater too. The major subdivision within this phylum consists of the gastropods, which represent slugs and snails. There are some 80,000 living species – and probably more. Unlike the situation with vertebrates, which tend to have been studied in some detail,…

The mountains and forests of Tanzania in East Africa are home to a diverse array of herptile species with many, such as globe eyed tree frogs (Leptopelis spp), the reed frogs (Afrixalus and Hyperolius spp) and dwarf chameleons (Rhampholeon) being familiar to many hobbyists. In recent years however, one species has perhaps stood out more than others, no doubt due in part to its distinctive colouration. A jolt from the blue First described in 1952, the electric blue or turquoise dwarf gecko (Lygodactylus williamsi) is a small blue lizard which lives in a tiny area of the Kimboza and Ruvu forest reserves in Tanzania. As their common name suggests, adult males of this species are an incredibly vivid shade of turquoise blue. Females and younger individuals tend to be somewhere…