Science notes, unit 3

Animals

Textbook Science Year 5 (DLP), pages 49–92

What this chapter covers

You can explain what the survival of an animal species means (3.1.1)
You can describe the body parts and behaviours that protect animals from enemies (3.1.2)
You can explain how animals protect themselves from extreme weather, including hibernation, migration and wallowing (3.1.3)
You can describe how animals protect their eggs and ensure the survival of their young (3.1.4, 3.1.5)
You can design an imaginary animal with characteristics that protect it, and say why they matter (3.2)
You can build food chains and food webs, and name the producers and consumers in them (3.3.1, 3.3.2, 3.3.4)
You can explain how energy from the Sun is transferred along a food chain (3.3.3)
You can predict what happens to other living things when a population changes (3.3.5, 3.3.6, 3.3.7)

Every animal faces danger: enemies, bad weather and hunger. Animals have special body parts and ways of behaving that keep them alive. In this unit you will learn how animals protect themselves, their eggs and their young, and how living things depend on each other for food.

3.1Survival of animal species

The survival of an animal species is the ability of animals to maintain their species and avoid extinction. Animals do this with specific characteristics (body parts) and behaviours (things they do).

A crab with big sharp claws on a rock and a horseshoe crab with a hard shell on a beach, with two large birds nearby — The crab has big, sharp claws. The horseshoe crab has a hard shell. Both help the species survive.

Protection from enemies

The tortoise pulls its body into its hard shell when an eagle attacks, so the eagle cannot hurt it. Other animals have different tools of defence.

A tortoise, a hermit crab and horseshoe crabs with hard shells on a beach while an eagle flies away — Hard shells protect the tortoise and the crab.

Body part or characteristic	Examples	How it protects
Stings that release venom	Bee, wasp, centipede	Hurts or kills the enemy
Bad smell	Bedbug, beetle, cockroach	Enemies do not come near
Patterns like fake eyes on the wings	Moth	Deceives (tricks) the enemy
Hard scales	Crocodile, arapaima fish	Protect the body from injuries
Big, sharp claws	Crab	Hurt or scare the enemy
Strong leg muscles	Horse, rabbit, frog	Run or jump fast to escape
Sharp horns	Deer, buffalo, gaur	Used for self-defence
Thick, hard skin	Buffalo, rhinoceros, elephant	Hard for enemies to bite or pierce
Sharp spines	Porcupine, pufferfish	Pierce enemies that touch them
Hard shell	Tortoise, horseshoe crab	Hides and shields the soft body

Bee, centipede and wasp; bedbug, beetle, cockroach and moth; crocodile and arapaima fish, with notes on their defences — Stings, bad smell, fake eyes and hard scales.

Horse, rabbit and frog with strong legs; deer, buffalo and gaur with sharp horns — Strong legs help animals run away. Sharp horns help them fight back.

Protection by behaviour

Behaviour	Animal	What happens
Raises its sharp spines (quills)	Porcupine	Enemies get pierced. It also runs into its burrow.
Inflates (puffs up) its body	Pufferfish	Looks three times bigger and has sharp spines, and it is poisonous.
Detaches a body part	Lizard (tail), octopus (arm)	The part keeps moving and distracts the enemy while the animal escapes.
Spurts out black ink	Octopus, cuttlefish	Enemy cannot see, so the animal swims away.
Withdraws body parts into the shell	Tortoise	Soft parts are hidden.
Curls or rolls up its body	Pangolin, millipede	Protects the head and the soft parts of the body.
Lives in groups	Ants, elephants	Reduces the risk of being attacked.

A porcupine with raised spines and an inflated pufferfish — The porcupine raises its spines. The pufferfish inflates its body.

A lizard that has dropped its tail near a bird, and an octopus and cuttlefish spurting black ink — Detaching a tail and spurting ink both help an animal escape.

A tortoise, pangolin and millipede curl up; ants and elephants live in groups — Hiding, curling up and living in groups.

A body part is something the animal has (shell, horns). A behaviour is something the animal does (curl up, spurt ink, live in groups). Name both when you answer.

A lizard loses its tail when a cat catches it. Name this behaviour and say how it helps the lizard.

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It detaches (drops) its tail. The tail keeps moving and distracts the cat, so the lizard can escape.

Protection from extreme weather

Some places are extremely cold or extremely hot. Animals there have body parts and behaviours that help them stay alive.

Weather	Characteristic or behaviour	Example	How it helps
Extremely cold	Thick fur	Polar bear	Traps body heat to keep warm
Extremely cold	Short, dense feathers	Penguin, snow goose	Waterproof and a thermal insulator
Extremely cold	Thick layer of fat under the skin	Walrus, sea lion	Keeps body heat in
Extremely cold	Small ear lobes	Walrus, sea lion	Reduce heat loss
Extremely cold	Hibernation	Polar bear	Sleeps through winter, moves little and saves energy
Winter in the home place	Migration	Whales, birds (milky stork, sandpiper)	Move to a warmer place to breed and to find food
Extremely hot	Hump of stored fat	Camel	Food store; survives about two weeks without food and water
Extremely hot	Large ear lobes	Desert fox, desert rat	Release more heat from the body
Extremely hot	Wallowing in water or mud	Buffalo, hippopotamus, elephant	Cools the body; stops insect bites, parasites and skin diseases

Hibernation is when an animal becomes inactive and sleeps through winter. Migration is when animals travel across continents or oceans to avoid cold weather. Wallowing is rolling in water or mud to cool down.

Two polar bears and a group of penguins on snow and ice — Polar bears have thick fur. Penguins have short, dense feathers.

A map showing the routes of migrating birds and whales around Australia and Asia — Birds and whales migrate to avoid the cold. Kuala Gula in Perak is a stopping place for birds.

Buffaloes wallowing in mud, a hippopotamus in water and an elephant in mud — Wallowing keeps buffaloes, hippopotamuses and elephants cool.

A camel with a hump, a desert fox and a desert rat in a desert — The camel's hump stores fat. Desert foxes lose heat through large ear lobes.

Did you know? Small ear lobes keep heat in (polar animals). Large ear lobes let heat out (desert animals). Same body part, opposite job!

A camel's hump stores fat, not water.

Why do whales and some birds migrate in winter?

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To avoid the cold weather of their home place. They go to warmer places to breed and to find food.

Protecting eggs and young

Animals protect their eggs and young so that their species does not become extinct.

Way of protecting eggs	Examples
Hide the eggs (in nests, tree holes, gaps, bushes)	Crocodile, woodpecker, cockroach
Incubate (keep warm) the eggs until they hatch	Crocodile, woodpecker, hen
Bury the eggs in the soil	Grasshopper, tortoise
Lay eggs on rocks or leaves near calm river water	Water strider
Lay a large number of eggs	Frog, toad
Slimy (covered with mucus) or smelly eggs	Frog, toad

A forest stream with a mousedeer, a frog, a toad, a crocodile and a mosquito, and what they say about their eggs — Hiding, burying, incubating and laying many eggs.

A tree where a woodpecker, a cockroach, a grasshopper, a water strider and a tortoise talk about their eggs — Hiding, burying, incubating and laying many eggs.

Animals also look after their young until they can look after themselves.

How the young are kept alive	Examples
Care for and suckle (feed with milk)	Rabbit, cat, goat
Carry in a pouch	Kangaroo
Carry in the mouth	Crocodile, tilapia fish
Attack enemies when the young are in danger	Hen, monkey
Feed the young	Birds, lions

Rabbits, cats, goats, a kangaroo with a joey, a tilapia fish and a crocodile with their young — Animals care for, feed and defend their young.

Chickens and monkeys guarding their young; a bird and lions feeding their young — Animals care for, feed and defend their young.

Frogs and toads lay many eggs, and the eggs are slimy and smelly. How does this help their species survive?

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The slimy, smelly eggs are hard for enemies to eat. Because there are so many eggs, some will survive and hatch.

The survival of species keeps the balance of the ecosystem. If one species disappears, other living things that depend on it are affected.

3.2Imaginary animal

Ana made a model of an imaginary animal. She chose a body part for each danger, and gave a reason for it.

Body part	Job
Scales	Protect from injuries
Antennae	Sensitive to touch
Nose	Very sensitive to unfamiliar smells
Small ear lobes	Reduce heat loss
Sharp spines and claws	Self-protection; scratch and grip the enemy
Thick fat and thick, smooth fur	Keep the body warm in cold weather (thermal insulator)

Designing your own animal

Step 1 Sketch the animal. Step 2 Label each characteristic and behaviour. Step 3 Say what each one protects against (enemies or weather). Step 4 Say what would happen without it.
Example: "My animal has thick fur. It is a thermal insulator, so it can live in the cold. Without fur it would lose body heat and may die."

Every animal has characteristics and behaviours that help it survive. This keeps the balance of nature, so we should look after animals and their habitats.

3.3Food chains and food webs

Food chain

A food chain is the food relationship among living things. The arrow (→) means "is eaten by". It also shows the flow of energy.

A food chain always starts with a plant (the producer). The arrow points to the animal that eats, not to the food.

Producers and consumers

Group	What it does	Examples
Producer	Makes its own food by photosynthesis, using sunlight	Plants: fruits, paddy, waterweed, vegetables
Consumer	Cannot make its own food; gets energy by eating other living things	Squirrel, snake, eagle, duck

The Sun is the main source of energy in an ecosystem. It gives light and heat energy.
Energy goes from the Sun to the producer, then to the consumer that eats it, and then to the next consumer.

A vegetable farm with goats, chickens, ducks, caterpillars and a snake, and five food chains starting with vegetables — Five food chains on a vegetable farm. Every one starts with the vegetable, the producer.

A paddy plant in a paddy field and an eagle, with notes that the Sun is the main source of energy and the eagle is the end consumer — The paddy plant (producer) takes in energy from the Sun. The energy passes to the duck and chicken, then the snake, and the eagle is the end consumer.

An ecosystem is a system of living things that live together, interact and depend on one another in a habitat, together with the water, soil, air and the Sun.

In the food chain paddy → chicken → snake → eagle, name the producer and the last consumer. Where does the producer get its energy?

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Producer: paddy. Last consumer: eagle. The paddy gets energy from the Sun (sunlight).

Food web

A food web is a combination of more than one food chain. An animal can eat more than one kind of food, so chains join up.

A pond with waterweed, snail, tadpoles, small fish, big fish, frog, grasshopper and storks — A pond habitat and its food web. Waterweed is the producer. Storks are at the end of every chain.

A food web of a pond: waterweed, snail, tadpoles, small fish, big fish, grasshopper, frog and stork — A pond habitat and its food web. Waterweed is the producer. Storks are at the end of every chain.

In the pond web, tadpoles, small fish, snails and grasshoppers all eat waterweed. Some animals eat both plants and animals; these are omnivores.

In a food web, the arrow points to the eater. Check the direction before you answer.

Effects of a change in population

A population is a group of living things of the same species in a habitat. A population change is a change in the number of a species.

Causes of a change: extreme weather, a pandemic (a disease that spreads widely), unplanned forest clearing, forest fires and illegal hunting.

Two food webs: one with waterweed, grasshopper, tadpoles, fish and stork; one with vegetable, grasshopper, chicken, goat, snake and duck — If all the fish die, the stork can still eat tadpoles and grasshoppers. The web is still connected.

Causes of a population change: forest clearing, forest fire and illegal hunting — Population change makes animals lose their habitat and food, die or move away.

Kangaroos, elephants and a tiger that have lost their habitat — Population change makes animals lose their habitat and food, die or move away.

Animals lose their natural habitat and food.
Animals die or move elsewhere to look for a new habitat.
Food relationships are disrupted, so the whole food web changes.

Predict

In a grassland, snakes eat frogs and frogs eat grasshoppers. If all the frogs die: grasshoppers will increase (fewer of them are eaten), and snakes will decrease unless they have other food.

Give two causes of a change in the population of animals in a forest.

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Any two: forest fire, unplanned forest clearing, illegal hunting, extreme weather, a pandemic.

Did you know? A mini terrarium is a transparent container with plants and small animals. It is a small copy of a habitat.

Pictures: Science Year 5 (DLP) textbook, pp. 49–92 (crab p. 50, tortoise p. 51, defences pp. 52–56, polar p. 58, migration p. 60, wallowing p. 61, desert p. 62, eggs pp. 64–65, young pp. 67–68, food chain p. 76, farm p. 79, paddy p. 80, food web pp. 82–84, situations p. 86, population pp. 87–88).

Summary

Topic	Key points
Survival of species	Ability to avoid extinction
Against enemies	Shells, stings, spines, scales, horns, bad smell, fake eyes, fast legs, detach parts, ink, curl up, live in groups
Against weather	Fur, fat, dense feathers, small ear lobes, hibernate, migrate, humps, large ear lobes, wallow
Eggs	Hide, incubate, bury, lay many, slimy or smelly
Young	Protect, suckle, feed, carry in pouch or mouth, attack enemies
Food chain	Producer → consumers; arrow means "eaten by"; energy flows
Food web	Several food chains joined together
Population change	Loses habitat and food; animals die or move; balance affected