Information on the Animal Classes Amphibians and Reptiles
What Are Amphibians?
Characteristics and Special Features of Amphibians:
- Vertebrates: They have an internal skeleton with a backbone.
- Double life: They inhabit both land and water.
- Metamorphosis: They transform from aquatic larvae (tadpoles) into adult forms.
- Moist skin: Their skin is typically wet and slimy, as they also breathe through their skin (cutaneous respiration).
- Cold-blooded: Their body temperature adjusts to the environment; in winter, they often enter a state of hibernation.
- Egg laying: Most lay their soft eggs without a hard shell directly in water.
The Evolution of Amphibians
Amphibians are classified as vertebrates and evolved between 416 and 359 million years ago from fish. Their name comes from Greek, meaning "double life." This aptly describes their way of living: unlike fish, they can partially live on land. They are generally divided into three groups: frogs, salamanders, and caecilians.
Amphibian Family Tree
Habitat
Where Can Amphibians Be Found?
Amphibians typically reside near water, as they would dry out in arid regions. Therefore, they can be found:
- In water
- On land
Diet
What Do Amphibians Eat?
The diet of amphibians can change throughout their lives. During the larval stage, most amphibians primarily consume plants. After metamorphosis, they predominantly eat meat. Their diet can include:
- Herbivores (plant-eaters)
- Carnivores (meat-eaters)
- Omnivores (both plant and meat-eaters)
Movement
How Do Amphibians Move?
Amphibians have various ways of moving. They can:
- climb (frogs)
- jump (frogs)
- run (salamanders)
- crawl (alpine newt)
- swim (frogs)
- dive (axolotl)
Reproduction
How Do Amphibians Reproduce?
Amphibians typically hatch from eggs and at this stage, they appear as small larvae that look nothing like their parents. It is only later that they undergo a transformation known as metamorphosis. This process changes them into adult animals. The term metamorphosis comes from Greek, meaning "transformation" or "change."
How Do Amphibians Differ From Other Animal Species?
The most noticeable distinction from other animal species is the metamorphosis they experience throughout their lives (see reproduction). Generally, they also possess thin and moist skin, except for toads, which have dry, leathery skin.
Fun Facts
Poison Glands
Many adult amphibians defend themselves against predators using toxins produced in specialized glands. The most famous of these are the poison dart frogs.
Amphibians in Winter
What do amphibians do in winter? Amphibians have several tricks up their sleeves to survive the frigid winter. The wood frog can even freeze itself, only to thaw out in the spring!
Species
There are about 8,600 species of amphibians:
| Frogs, toads: | 7,550 |
| Salamanders, newts, olms: | 780 |
| Caecilians: | 215 |
What Are Reptiles?
Characteristics and Special Features of Reptiles:
- Vertebrates: Reptiles possess a solid bony skeleton and a spine.
- Scaly skin: Their bodies are protected by dry, hard scales that help prevent dehydration.
- Molt: Since their scaly skin does not grow with them, many reptiles (like snakes) need to shed their skin regularly.
- Eggs with shells: The young typically develop in eggs, which are often laid on land.
- Lung breathing: Unlike amphibians, reptiles breathe solely through their lungs from birth.
- Cold-blooded: They regulate their energy through sunlight and must actively warm up to remain agile.
The History of Reptiles
Reptiles are part of the vertebrate family and have inhabited the Earth for over 315 million years. They evolved from amphibians. The term comes from Latin, where "reptilis" means "creeping." Reptiles include turtles, lizards, snakes, and crocodiles.
Reptile Family Tree
Habitat
Where Can Reptiles Be Found?
Reptiles primarily live on land, while others spend most of their time in water and only come ashore briefly. They can be found:
- In water (sea turtles)
- On land (toads)
Movement
How Do Reptiles Move?
Most reptiles are excellent swimmers, and some are also good climbers. Reptiles like snakes lack legs and travel by slithering across the ground.
- climbing (chameleons)
- jumping (basilisks)
- running (Komodo dragons)
- crawling (snakes)
- swimming (crocodiles)
- diving (alligators)
Diet
What Do Reptiles Eat?
Most reptiles are carnivorous, feeding on invertebrates, mammals, and other reptiles. Some species also consume plants. Pure herbivores are quite rare.
- Carnivores (meat-eaters)
- Omnivores (eating both plants and animals)
- Herbivores (plant-eaters)
Reproduction
How Do Reptiles Reproduce?
This is fascinating! Reptiles reproduce in various ways depending on the species:
- Oviparous: They lay eggs (turtles)
- Ovoviviparous: They give birth to live young from eggs (blindworms)
- Viviparous: They give birth to live young almost like mammals (skinks)
How Do Reptiles Differ From Other Animal Species?
Primarily through their scaly skin. It grows throughout their entire life. Turtles and crocodiles form a shell from it. Snakes and lizards must shed their skin at regular intervals because it does not grow with them and becomes too tight. This process is quite impressive in snakes, as they often shed their old skin in one piece.
Fun Facts
Body Temperature
Both reptiles and amphibians have no consistent body temperature, which is why they are referred to as cold-blooded. To raise or lower their body temperature, they enjoy sunbathing or retreating to cool caves. This allows them to conserve more energy than mammals.
Species
There are about 9,500 species of reptiles:
| Snakes: | 3,900 |
| Iguanas: | 2,000 |
| Skinks: | 1,275 |
| Geckos: | 980 |
| Turtles: | 360 |
| Anguimorpha: | 350 |
| Crocodiles: | 26 |
| Tuataras: | 1 |
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- The Most Dangerous Venomous Snakes: Africa
- The Most Dangerous Venomous Snakes: Asia
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