Reptiles
Reptilia
INDEX
WHAT ARE REPTILES?
TYPES OF REPTILES
MAMMAL REPTILES
WHERE DID MAMMALS COME FROM?
REPTILES, MAN AND CONSERVATION
REPTILES OF THE BAHAMAS
REPTILES OF ARDASTRA
WHAT ARE REPTILES?
The Reptilia (from the latin “to creep”) generally refers to vertebrates (have a backbone) that are covered in dry scaly skin, are cold blooded (use the environment to maintain their body temperature), breathe through lungs and nearly all of them hatch from eggs. Reptiles are found on all continents of the world, except Antarctica and in many different habitats of the world but as they are cold blooded they are most abundant in the warmer habitats.
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TYPES OF REPTILES
There are approximately 8,000 different species of reptiles in 4 different orders.
The different orders are as follows:
Crocodilia – crocodiles, gharials, caimans and alligators
Sphenodontia – tuataras from New Zealand
Squamata – lizards, snakes and worm-lizards
Testudines – turtles and tortoises
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REPTILE FEATURES
Each group of reptiles has its own distinctive characteristics but all reptiles share certain features.
Cold blood
The metabolism of reptiles does generate a little heat but it is not enough to sustain a constant body temperature. Therefore they use the environment to help regulate their body temperature and are referred to as cold blooded animals or ectothermic (“from outside temperature”). However, the only known exception to this rule is the leather back turtle which has been known to elevate its body temperature well above that of its surroundings. There are some benefits to being cold blooded. Animals that use the environment to help regulate their temperature have lower metabolisms and that means that they do not need to eat as much or as often to fuel their metabolic rate. And therefore, the cold blooded animals often do well in places (or during times) of limited food source.
Scaly beasts
Reptiles are covered in thin over-lapping flat plates of a protein called keratin that we refer to as scales. These over-lapping scales form a protective barrier over the skin. The scales come in many different colors and patterns and help the reptiles to camouflage, communicate with other reptiles or to warm off danger.
Reptilian reproduction
Most reptiles reproduce by sexual reproduction, involving both a male and a female to produce young. However, there are six families of lizard and one family of snake that have been known to asexually produce young in a process known as parthenogenesis.
Nearly all reptiles hatch from an egg, known as Oviparous reproduction. A small number of these reptiles however, retain their eggs inside them until the eggs hatch and the young come out of the mother as live young. This is known as Ovoviviparous reproduction and is found in a few species of snakes, namely the boa constrictors. However, a very small number of reptiles are known to produce truly live young, termed Viviparous reproduction, where the young are not encased in a shell and are connected to the mother via a primitive placenta-like connective tissue. This has been documented in several Australian snakes and a number of lizards.
Reptilian breathing
All reptiles use lungs to breathe. However, different reptile groups breathe in different ways. For example, the lizards and snakes use the same muscles for breathing as they do for moving and so they must hold their breath while making a quick getaway. The crocodilians use a diaphragm muscle that is similar to mammals but this diaphragm also moves a movable part of their pelvis which allows the liver to move and make room for the lungs to further expand. The Turtles have lungs that are encased in a rigid shell and so they have come up with several ways to combat this problem. Many turtles stretch out and retract their limbs to enable their lungs to expand and so breathing is done during locomotion. Turtle also have developed more permeable skin and even gills in their anal region to aid the breathing process.
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WHERE DID REPTILES COME FROM?
The reptiles are an ancient group of animals that first appeared on this planet about 320 million years ago. What made these animals different from their amphibian ancestors was in their eggs. They were the first vertebrates to produce eggs that were encased in a shell rather than jelly like the amphibians. This prevented the eggs from drying out and therefore the reptiles could go on land and not have to return to the water to lay their eggs. The reptiles also have tough skin which is covered in scales and prevents them from loosing too much moisture from their skin. The earliest known reptile was probably Hylonomus and the first “true reptiles” are a group known as the Anapsids. These were very lizard-like in appearance and their teeth suggest that they were insectivorous (insect eating). In fact, the earliest reptiles are thought to have evolved in tandem with the many insect groups that were beginning to colonize the land at that time. The reptiles thrived on land for hundreds of millions of years and became some of the largest land animals to have ever walked the planet, the dinosaurs.
Many of these early reptiles died out 65 million years ago along with the dinosaurs. The only living Anapsids still alive today are the turtles and the only living relative to the dinosaurs (archosaurs) still alive today are the crocodilians and birds. However, the relatively recent group of reptiles, the lizards and snakes have become the most successful group of reptiles living today and have adapted to a large range of habitats and niches around the world.
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REPTILES, MAN AND CONSERVATION?
Reptiles have been on this planet for an extremely long time and have survived 3 mass extinction events throughout their existence. The last mass extinction did end the reign of reptiles to give way to the mammals as the dominant vertebrates on the land. However, it has not been until humans began to exploit the reptiles that these animals as a whole have seriously faced extinction.
People have exploited retiles from the beginning of time by eating their meat, eggs and using skins, shells, teeth and other bodily parts for ornamentation. On top of this, reptiles have suffered the effects of habitat loss from deforestation, as well as coastal and wetland development. And some, particularly the snakes and crocodilians have been killed simply out of fear.
A small number of reptiles have actually benefited from some human activities. For example the
Brown Anole
( Anolis sagrei) form Cuba and the Bahamas has been introduced in many regions of the tropical Americas mostly by accident and is now quite common in places like Florida.
REPTILES OF THE BAHAMAS
The Bahamas has many different reptiles that either once roamed the Bahamas or still do. Many of the reptiles living in the Bahamas today are facing extinction as are most reptiles on small, populated islands. The table below gives a brake down of the different reptiles found in the Bahamas (follow the links for further information).
REPTILES OF ARDASTRA
Ardastra has many reptiles as part of its collection but there are many Bahamian native reptiles that can also be seen throught the park.
Reptiles housed in Ardastra include:
Snakes, Lizards, Iguanas, Crocodilians and Turtles.
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