How reptiles are built, where they live and why they matter, ahead of National Reptile Awareness Day on 21 October
Types, Diet, Habitats and Breeding
Reptiles are air-breathing, scaly vertebrates that rely on their surroundings for body heat and, for the most part, lay eggs on land. That description covers crocodiles, tortoises, snakes, lizards and chameleons, animals that look very different from one another but share a common body plan and a common way of managing heat and water. National Reptile Awareness Day, observed each year on 21 October, is a good moment to look at how that body plan works and why the group deserves more attention than it usually receives on safari.
Africa is a productive place to study reptiles because so many of the main groups live side by side, from Nile crocodiles in the Okavango Delta to Namaqua chameleons in the Namib Desert. This guide covers what reptiles are, the different kinds, how they are put together, where they live, what they eat and how they reproduce, and it finishes with where to see them on safari.
A plain-language definition before the detail
What Is a Reptile?
A reptile is an air-breathing vertebrate with dry, scaly skin that depends on its environment for body heat and produces eggs with a protective shell or membrane that can be laid on land. Reptiles live on every continent except Antarctica, and roughly 12,000 species are currently described.
The word cold-blooded is common shorthand, but the more accurate term is ectothermic. A reptile generates very little of its own heat, so it moves between sun and shade to keep its body within a workable range, often basking in the morning and retreating to shelter at midday. That habit is why a cool morning drive is a good time to find lizards and tortoises on open ground.
Different Kinds of Reptiles and Their Taxonomy
Living reptiles are traditionally sorted into four orders. Squamata, the scaled reptiles, includes lizards, snakes and the burrowing worm lizards, and it accounts for more than 95 per cent of all reptile species. Testudines covers turtles, terrapins and tortoises, more than 300 species in all, each with a shell built from fused ribs and bony plates. Crocodilia contains about 25 species of crocodiles, alligators, caimans and gharials. Rhynchocephalia has a single living member, the tuatara, which is found only in New Zealand.
Taxonomy is a moving subject. Modern classification is based on shared ancestry, and on that basis crocodilians are more closely related to birds than they are to lizards, because birds descend from a group of dinosaurs that sits close to crocodiles on the family tree. Scientists therefore often treat birds as a living branch of the reptile lineage, which is why the traditional group called Reptilia is regarded as incomplete without them. For safari purposes the working definition above is the useful one, and it is the one this guide uses.
Scales, lungs and hearts suited to a life lived at the temperature of the day
How Reptiles Are Built
Reptile skin is covered in scales made of keratin, the same protein found in human nails. The scales are waterproof, which allows reptiles to live in dry country that would defeat most amphibians. Snakes usually shed their skin in one piece, while lizards tend to shed in patches, and a snake with cloudy eyes is often close to shedding.
All reptiles breathe with lungs, including sea turtles and sea snakes, which surface to take in air. Most have a three-chambered heart with two atria and one ventricle, while crocodilians have a four-chambered heart, closer in design to that of a bird or mammal. Because they do not spend energy on keeping warm, reptiles need far less food than mammals of similar size, and a large crocodile can go for months between meals. Size varies enormously: the Jaragua dwarf gecko measures about 17 millimetres, while the saltwater crocodile can exceed six metres.
From desert dunes to wetland channels and warm ocean beaches
Where Reptiles Live
Reptiles have settled almost every warm habitat on the planet, and a safari can take you through most of them. Nile crocodiles and Nile monitors work the rivers and channels of the Okavango Delta, the Chobe and the Zambezi. Rock agamas and flat lizards colonise granite outcrops and sun-warmed walls. The Namib Desert supports specialists such as the Namaqua chameleon and Peringuey’s adder, both adapted to heat and scarce water, while Madagascar holds around half of the world’s chameleon species, mostly in its forests.
The sea is part of the picture too. Green, loggerhead and leatherback turtles live in warm coastal waters, and females return to sandy beaches to nest. In South Africa, loggerheads and leatherbacks nest on the beaches of iSimangaliso Wetland Park between roughly November and February. In cooler regions reptiles slow down or brumate through the cold months, so timing a trip for the warmer season improves the chances of a sighting.
Ambush, endurance and a few species that prefer leaves
Feeding Habits and Diet
Reptiles have settled almost every warm habitat on the planet, and a safari can take you through most of them. Nile crocodiles and Nile monitors work the rivers and channels of the Okavango Delta, the Chobe and the Zambezi. Rock agamas and flat lizards colonise granite outcrops and sun-warmed walls. The Namib Desert supports specialists such as the Namaqua chameleon and Peringuey’s adder, both adapted to heat and scarce water, while Madagascar holds around half of the world’s chameleon species, mostly in its forests.
The sea is part of the picture too. Green, loggerhead and leatherback turtles live in warm coastal waters, and females return to sandy beaches to nest. In South Africa, loggerheads and leatherbacks nest on the beaches of iSimangaliso Wetland Park between roughly November and February. In cooler regions reptiles slow down or brumate through the cold months, so timing a trip for the warmer season improves the chances of a sighting.