"You can't trample infidels when you're a tortoise. I mean, all you could do is give them a meaningful look." – Terry Pratchett
We’re talking about tortoises here – those groovy little animals with the stumpy legs and wizened old faces… Yeah, you know the kind. Generally people tend to use the word tortoise and turtle interchangeably, or it varies depending on where you are in world – in Australia only sea turtles are called turtles, everything else is called a tortoise, while in America the word turtle is generally accepted to mean pretty much anything with a shell. Some languages only have one word for anything answering to that vague description.
However, in basic zoological terms the fundamental difference between them lies in their habitat. A tortoise is a land dwelling animal, and its body is built as such, whereas a turtle spends most of it’s time in water and only comes on to land sometimes, for example when it wants to lay eggs. However, turtles and tortoises are very similar and thus much of what can be said about a tortoise also holds true for a turtle. You can find these great animals in temperate and tropical regions all over the world, although strangely enough, Australia has no true tortoise species.
Chelonia is from the Greek word for "tortoise shell" jewellery, but it refers to all tortoises and turtles. The "ch" is a transliteration of the Greek letter c which is pronounced "key". The Greek ch is the letter "k" so Chelonia is pronounced "Kelonia." Testudo is Latin for "turtle".
Making up species names for tortoises is pretty straightforward. For example, the giant Galapagos tortoise is Geochelone elephantopus - The earth (geo) turtle (chelone) with the elephantine (elephanto) feet (pus). Cool!
So what do tortoises look like then?
There are upwards of 40 tortoise species out there, in as many permutations as one could imagine, but they all share the same clever characteristics that have evolved over many millions of years to make them one of the toughest types of animal around.
Most people would first think of a tortoise in terms of its shell. This makes sense as it is, in a both a literal and figurative sense, the backbone of the animal. The shell is made up of about 60 small bones and is covered by the many plates you see on the outside – these are called scutes. The shell is actually part of the tortoises’ skeleton, so it can’t crawl or fall out of it as so often happens in stories. However many tortoises have the ability to tuck their head and legs right inside the shell to protect them from predators as the shell is very hard.
The upper shell is called the carapace and is made up of modified ribs and vertebra and coved with the bony plates. This is attached to the tortoises’ ribs and spine. The lower shell is called the plastron and evolved from the shoulder and collarbones. This is attached to the carapace by a very strong bony structure called the bridge.
Although the shell is built up much like human finger-nails it is a far more alive and integral part of the tortoise and they can feel pressure and pain through it. The shell plates are usually a motley collection of colours such as yellow, brown, green and black and are well suited to camouflaging the tortoise in its natural habitat. The shells are usually patterned with radiating rings or lines – hence the term tortoiseshell. People sometimes try and use these rings to tell the age of the tortoise, like one can do with trees, however this isn’t very accurate as tortoises go through many irregular periods of growth and near hibernation depending on their environment.
A tortoise has short, stumpy hind legs, much like the ones you’d find on an elephant – the bottom of the feet are covered in an incredibly tough layer of leathery skin that allows the tortoise to live in even the harshest environments. The front legs are slightly more flattened and are often used like scoops for digging or for handling pieces of food. There are also small claws on all the feet which help with digging and walking on tough terrain.
Most species of tortoise also have a very short tail. This, as well as the legs, head and neck are covered in small scales. These provide a lot of protection but are much more sensitive to touch than they look. Since tortoises are reptiles they are cold blooded and so can often be found basking in the sun and many go into hibernation during the winter as it is too cold for their bodies to operate normally.
What about tortoises senses?
They called him tortoise because he taught us – Alice in Wonderland
Tortoises do not have true ears like people and many other animals. Instead they have two tiny openings on the side of their head that are very sensitive to vibration and pressure changes. Combined with an excellent sense of smell the tortoise is very adept at finding food and watching out for predators. Tortoises also have very good eye sight considering that the eyes are always small in relation to the head and body. Most tortoise species show very strong attractions to certain colours when looking for food – especially red. Tortoises’ eyes are very sensitive though, and looking at them can often be invaluable when trying to determine the tortoises’ state of health.
Tortoises also seem to have a strong set of homing and navigation instincts, as many types of tortoise roam large areas, and even migrate along certain routes yet often return to the same site for breeding. Tortoises are also renowned for moving slowly, and this is most certainly an aspect where they live up to their reputation – the average speed of a tortoise is about 0.5 miles an hour, yet they make up for it with stamina and can cover huge distances.
Many people imagine that tortoises do not vocalize at all, but that is not the case. Although they are perhaps amongst the quietest in the animal kingdom all males have some type of mating call and many make a noise when threatened. Usually it sounds like a very soft hissing or spitting noise. They can also be pretty noisy when they eat – even if it’s unintentionally.
The turtle lives 'twixt plated decks
Which practically conceal its sex.
I think it clever of the turtle
In such a fix to be so fertile.
- Ogden Nash
Male tortoises have a concave plastron which allows them to mount a female tortoise from behind. Males are very territorial and will engage in battle with any male that enters their territory during mating season; similarly they will try and mate with any female that happens to roam in the vicinity. Once fertilization has taken place the female will dig a hole in the ground or clear a space in some vegetation, she will then lay the eggs into the clearing. Depending on the species it may be just 3 or 4 large oblong eggs, or upwards of 50 smaller round ones and the incubation period ranges from about 3 to 12 months.
Once the eggs have been laid the parental role is over. All babies have an egg tooth which they use to break out of the shell when the hatching time comes. They are then completely on their own and they must dig their way out of the nest, find food and learn to avoid predators within a very short time frame. It is often the case that only about 10% of the hatchlings survive the first few days. Once that’s over, tortoises have incredibly long lifespans – even the shortest living ones only reach full maturity at about the age of 20 and many species age well into their 100’s.
With many species the temperature of the nest determines the hatchlings sex – warmer nests produce more males and cooler ones more females. This factor has proved invaluable in tortoise breeding programs where a boost in breeding is needed to try and make sure that a species does not become extinct. Female tortoises also have the ability to store sperm and can produce fertile eggs from it over as many as three seasons.
What would they serve at a tortoise restaurant?
Some tortoise species are herbivores and live on a diet of grasses, shrub vegetation, leafy plants, flowers, fruit and cacti. There are also many kinds that are omnivores and, as well as eating their greens, will feast on worms, insects, snails, frogs and even small snakes. No tortoises have teeth, instead their mouths have a hard sharpened edge that forms a sort of beak, and combined with tremendous jaw strength a large tortoise could probably break your finger, so they have no problem with the soft diet they survive on.
When tortoises are kept as pets a careful diet is the most important thing to strive for. Because tortoises roam so far in the wild they are always finding things to munch on and make sure that they get the nutrients they need and avoid plants that are poisonous to them. In captivity this may not be the case and so they are often fed with supplements, particularly those that contain calcium which helps keep their shell strong.
Tortoises rarely drink from standing water as they get most of the moisture they need from the plants they eat and they can go for very long periods without drinking at all. Sometimes in times of drought or before hibernation they will drink very large amounts as their bodies are capable of storing it and releasing it slowly as it’s needed.
Where did they come from and how long are they going to be around for?
In the beginning
there was a great tortoise
who supported the world.
all ultimately rests.
He is all wise
and can outrun the hare.
in the night his eyes carry him
to unknown places.
- William Carlos Williams
Tortoises are the oldest living group of reptiles and probably first appeared about 200 million years ago! Stupendemys geographicus was one such tortoise and was probably about 10 feet long and weighed 4,000 to 5,000 pounds. Unfortunately, in today’s world there are 49 species of tortoise and turtle that are on the endangered list. Along with the dodo, the Galapagos tortoises where hunted relentlessly by sailors and although there are some living that are at least 150 years old most of them are relatively young as the population has only recently begun to recover. Other species have been put in danger by humans encroaching on their natural habitat – the Desert Tortoise population has declined by 90 percent since the 1980s. Many countries now have laws that prevent the sale of tortoises as pets, the capturing of wild tortoises and the import or export of certain species.
Many species of tortoise are also desirable for their flesh and eggs and despite efforts to limit this trade much poaching still takes place. Although not such a threat for tortoises, some of their turtle family members have also been hunted to near extinction due to the demand for ‘tortoiseshell’ that is used for making jewellery and fashion accessories. Their skin is also used as it makes highly prized leather.
There are some really interesting tortoises out there:
- The African Pancake tortoise has a shell that is incredibly flat and flexible. When it is in danger it will run into a crack or under a rock and then take a deep breath to inflate its body. Its shell expands and it becomes tightly wedged such that a predator cannot pull it out.
- The Gopher tortoise can dig very fast and spends almost all of its time underground in dug-out burrows that can be meters long. It often shares this home with other small reptiles and snakes.
- The average Giant Galapagos tortoise is about 1.5 meters long and weights about 250 kilograms.
Unlike most other reptiles like snakes and crocodiles, tortoises have never been animals that humans fear. Indeed they are often seen as symbols to be praised for their steadfastness, longevity and gentle nature and in Ancient Rome where even seen as a symbol of fertility. In fact the tortoise can be found represented in all major mythologies from around the world, be it Indian, Buddhist, Greek or Chinese. They also feature heavily in Western fables and literature.
Tortoises are always thought of as seeming wise beyond their years and privy to some secret of life that keeps them living long and happy lives. Of course we can never really know this about a tortoise, but there really is much to admire in such capable and diverse creatures and with such a calm and gentle nature they can make for surprisingly rewarding company when given the care they need. So go on – save the amazing creatures and you might just get a glimpse at their charming nature.
- The World Book Encyclopaedia - T
- Sandiego Zoo website - http://www.sandiegozoo.org
- Interesting Turtle Facts by Dr. Nancy Anderson - http://petplace.netscape.com/Articles/artShow.asp?artID=4385
- The turtle pages - http://theturtlepages.crosswinds.net