How animals are born: oviparous and viviparous animals
Aprende
All animals are born, but not all are born in the same way. Some hatch from an egg. Others are born from their mother’s body.
An oviparous animal hatches from an egg. The mother lays the egg and the baby grows inside it. When it is ready, it breaks the egg and comes out. Birds, such as the hen, are oviparous. So are almost all reptiles, amphibians, fish and insects.
An oviparous animal hatches from an egg Eggs are not all the same. A hen’s egg has a hard shell. Frog eggs are soft, like jelly, and are in the water.
Hen’s eggs and frog eggs Some oviparous animals look after their eggs. The hen warms them with her body: this is called sitting on the eggs. Others, like many frogs, leave them alone.
A viviparous animal grows inside its mother and is born already formed. Then it drinks her milk. Almost all mammals are viviparous: the dog, the cow, the dolphin, the bat and people.
How animals are born There are some curious cases. The platypus and the echidna are mammals, but they lay eggs. The viper, which is a snake, and some sharks do not lay eggs: their babies are born alive.
animal it is a how it is born platypus mammal from an egg viper reptile born alive some sharks fish born alive Three curious cases To find out how an animal is born, ask yourself: does its mother lay an egg, or does the baby grow inside her?
Worked examples
Ejemplo 1
Ellie’s hen is sitting on her eggs in the nest. How will the chicks be born?
- The hen is a bird.
- Birds are oviparous: they lay eggs.
- The hen keeps the eggs warm with her body. The chicks will hatch from them.
The chicks will hatch from eggs: the hen is oviparous.
¡Ojo! Many children think that only birds lay eggs.
Ejemplo 2
Julie sees a dolphin swimming with its baby. Does the dolphin lay eggs?
- The dolphin lives in the water, but it is a mammal.
- Almost all mammals are viviparous.
- The dolphin’s baby grows inside its mother and is born already formed.
The dolphin does not lay eggs: it is viviparous.
¡Ojo! Many children think that animals that live in the water lay eggs.
Ejemplo 3
Gus reads that the platypus is a mammal. How is it born?
- The platypus has hair and its babies drink milk: it is a mammal.
- Almost all mammals are born from their mother’s body.
- But the platypus is a curious case: it lays eggs.
The platypus hatches from an egg, even though it is a mammal.
¡Ojo! Many children think that no mammal lays eggs.
Un reto para pensar
Look at a book about animals with an adult. Find three animals that hatch from an egg and three that are born from their mother’s body. Draw them in two columns. Do not touch any nests or eggs you find in the countryside.
Practica
Rondas de 10 preguntas. Elige el nivel:
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