Living Things

vocabulary: basic needs, organism, reproduction, environment, respond, cell

An organism is a living thing. How can you tell an organism from a nonliving thing? A living thing grows. It starts out small. Then it gets bigger. Organisms also change as they grow.

The way a living thing changes during its life is called development. An oak tree begins as an acorn. Then it grows to a young tree. Its branches and trunk become thicker and stronger. The oak tree changes shape and color as it develops.

Another feature of living things is that they make more of their own kind. Reproduction is the way living things make more of their own kind. Plants grow from seeds. Chicks hatch from eggs. Some animals, like puppies, are born live.

All organisms live in an environment. An environment is made up of everything that surrounds an organism, including the air, water, soil, and even other organisms. An organism responds to its environment. To respond means the way a living thing reacts to changes in its environment. The leaves on trees respond to a change in environment by turning color in autumn. Bears respond by sleeping in a cave in the winter.

Living things use their senses to gather information about their environment. When living things share information by sending, receiving, and responding to signals, they communicate. They use their senses of sight, smell, hearing, and touch to collect information. Living things communicate in different ways. Some birds sing to mark their territory or area. Skunks sometimes spray a strong-smelling liquid to communicate.

Needs of Animals

vocabulary: migrate, hibernate, basic needs, environment

To live and grow, animals need food, water, air, and a place to live. Food gives an animal energy. Energy is the ability to do work. Different animals get food in different ways. Some animals eat only plants. Some eat only animals. Some animals eat both plants and animals. Most animals’ bodies are made up mostly of water. Water has several important jobs. It helps the body use food as fuel. It helps some animals stay cool. It helps get rid of body wastes.

All animals need air because it contains oxygen. Oxygen is a gas that is in air and water. Oxygen is an important gas. Animals can live for a few days without food or water. However, they would die in just a few minutes without oxygen. All body parts need oxygen to live and grow.

Some needs, like the need for food, are inner needs. Signals inside an animlal’s body tell it what to do to respond to an inner need. When you are hungry your brain tells you to eat.

All animals need a place to live. Animals respond to changes in the environment in different ways. Bats return to their caves to sleep. When the weather gets colder and the days get shorter, some animals gather food for the winter. Geese and butterflies migrate. To migrate means to move to another place. Bears and other animals find places to hibernate. To hibernate means to rest or sleep through the cold winter.

Grow and Develop

vocabulary: metamorphosis, learned traits, inherited traits, reproduction

Organisms change as they grow through their life cycle. A life cycle is all the changes in an organism’s life. Organisms go through stages. At birth, the organism’s life begins. As an organism lives, it grows and changes. It may take on a new form. During reproduction, an organism creates new organisms like itself. At death, the organism’s life ends.

Like people, some organisms get larger as they grow older. Unlike people, some organisms go through a life cycle change called metamorphosis. Metamorphosis means a change in the body form of an organism. Big changes take place in insects like the butterfly. Other animals, such as frogs and toads, also go through metamorphosis. Young frogs live only in water. Adult frogs live both in and out of water. Their bodies must change to live in both places. Other animals like birds, turtles, cats, and bears do not go through metamorphosis.

What makes you you? You have inherited traits. Inherited traits are characteristics that come from your parents. How do you inherit traits? People start out life as an egg. The egg contains special material from both parents. This material determines your traits.

Not all traits are inherited. Some are learned traits. A learned trait is something that you are taught or learn from experience. You learn to ride a bicycle or speak a language.

Animal Parts

vocabulary: tissue, organ, system, adaptation

Animals can have four main kinds of parts. Each part helps it survive in some way. 1) support and protect: these include skin, shells, feathers, scales, and bones. 2) move: arms, legs, wings, and fins are moving parts. 3) information gathering: eyes, ears, skin, noses, and tongues gather information. 4) intake materials: mouths, noses, skin, and other openings in organisms can take in materials.

Body parts are made of smaller parts. These smaller parts work together in systems. A system is a group of parts that work together.

Bones and muscles form a system that supports your body and helps animals move. Being able to move helps animals survive. Moving parts help animals get food, escape from danger, and build or find homes. Different body parts collect different information. Eyes get light information. Ears receive sounds. The skin gets information from touch.

Some parts of animals take in materials to get energy. Animals take in food and oxygen. Animals breathe gases in and out through lungs or gills. Most large organisms also have liquid and solid wastes. Special systems in their bodies get rid of these wastes.

Animal Groups

vocabulary: fish, amphibians, reptile, bird, mammal, herbivore, carnivore, omnivore

Animals may be classified in many ways. They may be classified by where they live, what they eat, or what they look like. Some animals have a backbone. Animals with backbones are called vertebrates. Turtles, frogs, fish, birds and cats are all vertebrates. Animals without backbones are called invertebrates. Invertebrates include, worms, starfish, spiders and flies.

A fish lives its whole life in water. Like people, fish need oxygen to live. Fish use their gills to get oxygen from water. The water enters the fish’s mouth, then moves through the gills behind the fish’s head. The gills take in oxygen, and the water passes out.

A fish is cold-blooded. Cold-blooded means that the body temperature changes with the surrounding temperature. When a fish is in cold water its temperature will drop. When a fish is in warm water its temperature will rise.

An amphibian is also cold-blooded. It spends part of its life in water and part on land. Frogs and salamanders are both amphibians.

A reptile lives on land and has a waterproof skin. Examples of reptiles include lizards, turtles and snakes. A reptile is cold-blooded. Reptiles need the sun to warm their bodies.

A bird has a beak, feathers, two wings, and two legs. Birds are the only animals that have feathers. Feathers keep birds’ bodies smooth so that they can fly or swim easily.

A mammal is an animal with hair or fur. A female mammal feeds its young with milk. Gorillas, whales, and cats are all examples of mammals. A mammal may have thick or thin fur or just a few hairs. Dolphins and elephants have just a few hairs. Mammals are warm-blooded. Their bodies stay at the same temperature, even when it’s very cold or very hot around them.