My Science School

A living thing cannot live alone. It depends on the other living things to supply the materials it needs to survive. We have seen how animals rely on plants for their food. Animals that only eat plants are called ‘herbivores’. Animals that eat other animals are called ‘carnivores’. A series of living things that feed on each other make up a “food chain”. If one of the members of the chain is removed all the others may be affected.

Often, several food chains interlink as many animals feed on a variety of plants or animals. The chains together make a ‘food web’.

 

 

 

 

 

 

 

 

 

 

 

 

Continue reading "LIVING WITH EACH OTHER"

 

Genes and chromosomes

Inside the nucleus of a human cell are 23 pairs of chromosomes. Along these chromosomes are “genes”. Genes control everything about you, including the way you look. Each of your cells has the same genes. You inherit two copies of every gene – one from your mother and one from your father. That is why you look like your parents.

 

 

 

 

Inheriting eye colour

The gene for brown eyes is known as a “dominant” gene – you only need to inherit one brown eye colour gene for your eyes to be brown. The gene for blue eyes is weaker. In general, a child will only have blue eyes if both inherited eye colour genes are blue. A man carries a gene for brown eyes and a gene for blue eyes, while the woman carries only a gene for blue eyes. One of their daughters has blue eyes because she has inherited two blue eye colour genes. The other daughter has brown eyes because she has inherited at least one brown eye colour gene.

 

 

 

 

 

There are different seashores all over the world. Some seashores are hot and some are icy cold. The animals found on icy seashore can live where it is very cold. They keep warm by having thick fur or oily feathers and a layer of fat under their skin.

 

 

 

 

These birds are looking for food in the mud.

When rivers reach the sea they spread out into wide, muddy seashore called an estuary. Huge flocks of birds feed on muddy estuaries. They hunt for worms, shellfish or crabs in the mud. When the sea flows into the estuary and covers the mud, the birds fly ashore and wait until it goes out again.

 

 

 

 

These penguins live on cold, icy seashore.

In very cold parts of the world, the seashore is icy. Penguins nest on the icy seashores of the Antarctic. It is so cold that they huddle together to keep warm. They keep their egg on top of their feet to stop it from freezing on the ice.

 

 

 

 

 

This seashore is in a hot part of the world.

Coral reefs grow in warm, shallow seas. Coral reefs are made by small animals that live close together. They protect themselves by building hard cases. It is the hard cases that form the coral reef. Coral reefs are important because they are home to many animals.

The waves that crash on to a seashore are very strong. Seashore plants and animals must hold on tight to keep themselves safe. If they let go, they could be washed away or smashed on the rocks.

 

 

These limpets are holding on to a rock.

Seashore animals have different ways of holding on. Limpets use their strong foot to grip tightly on to rocks and stop them from being washed away. Some animals, like sea urchins, cling on to rocks with lots of tiny feet that look like tubes. Mussel shellfish anchor themselves down to rocks with tough threads.

 

 

 

 

This seaweed grips on tightly to the rocks.

Seaweeds anchor themselves on to rocks to stop them from being washed away by strong waves. Large seaweeds grip on to rocks with strong, finger-like rootlets called holdfasts. During storms, seaweed is ripped off rocks.

 

 

 

 

 

Sea otters wrap themselves in seaweed.

When sea otters sleep, they wrap themselves in giant kelp seaweed. They grab a floating end of kelp and spin around in the water. The kelp wraps around the otter and anchors it down. It stops the sea from carrying the sea otter away in its sleep.

 

 

 

 

Shellfish are small animals that live inside shells. Their hard shells help to keep them safe from being eaten by other animals or smashed by waves. When shellfish are out of water, their shells stop them from drying out.

 

 

 

 

 

      These shellfish live in one shell.

Some shellfish live in one shell. The animal that lives inside has a very strong, muscular foot which it uses to move itself and to cling to rocks with. If the animal is in danger, it withdraws and hides inside its shell. These shellfish feed on seaweed or on other animals.

 

 

 

 

This shellfish has two shells joined together.

Some shellfish have two shells that are hinged together. Scallop shellfish swim by flapping their shells open and shut. Shellfish with two shells feed by sucking in water, and straining out small bits of food.

 

 

 

 

 

This hermit crab lives in an old shell.

Hermit crabs have a long soft body which they protect by living in an empty shell. They have a pair of strong hooks on their rear end to hold them safely in their shell. When a hermit crab grows too big for its shell, it will find a bigger shell to live in.

 

 

When the tide goes out, some water is left behind in hollows in the rocks. Many different seaweeds and animals live in these rock pools. They can stay safely underwater in the rock pool until the sea comes in again.

 

 

 

 

 

Starfish live in rock pools.

 

The underside of a starfish is covered with lots of tiny tube feet. It uses the feet to move and to grip on to rocks. Starfish feed on shellfish and use their arms to force open the shells to reach the soft animal inside. If a starfish loses any of its arms, it can grow new ones.

 

 

 

 

 

Sea anemones are animals.

Sea anemones look like flowers, but they are animals. They catch food with their tentacles. When a sea anemone is out of the water, it pulls in its tentacles to stop itself from drying out. It looks like a blob of jelly!

 

 

 

 

 

This is a rock pool food chain.

A food chain shows the link between plants and animals in a habitat. All food chains start with plants, which are eaten by plant-eating animals. Plant-eaters are eaten by flesh-eating animals. In a rock pool, seaweeds are food for animals like limpets. Limpets are eaten by whelks.

 

 

 

Many seashore animals bury themselves in the sand, mud or rock. They dig themselves in to try to keep themselves safe from being eaten. Some animals hide in the sand when the tide is out. This stops the animal from drying out in the wind or Sun.

 

 

 

 

 

These are lugworm casts on a sandy beach.

Lugworms live in U-shaped burrows on sandy or muddy seashores. They swallow mud and eat any pieces of food they find in it. The sand comes out of the worms’ bottom at the other end of the burrow, and makes a squiggly worm cast on the surface of the mud.

 

 

 

This dog whelk hides in cracks in rocks.

Some shellfish protect themselves by digging into rock or squeezing into gaps between rocks. Dog whelks hide under rocks, crawl into cracks and wedge themselves into crevices on rocky seashores when the tide goes out. When the tide comes back in the dog whelks come out to feed.

 

 

 

 

Cockles bury themselves in the sand.

Cockles use their muscular foot to bury themselves in the sand. This helps to protect them from being eaten by birds and animals. Cockles and razorshells feed using long siphons that suck water and strain food from it.

 

 

Many plants live on the seashore. Seaweeds are seashore plants that can live in salty seawater. Some seashore plants can only live on the land. They grow high up the shore, out of the reach of the waves.

 

 

 

 

 

This seaweed floats in the water.

Bladder wrack seaweed has pockets of air and jelly to help it float in the water. Its tough leathery leaves are covered in a slippery, gummy substance to protect it from drying out at low tide. Bladder wrack can survive out of water while the tide is out.

 

 

Seashore birds feed on different foods. They hunt for food on the land and in the sea. Some birds dig in the sand to find worms and shellfish. Fish-eating birds dive into the sea to catch their food.

 

 

 

 

 

 

 

 

Seashore birds build their nests on steep cliffs.

Seashore birds often nest together in huge, noisy colonies. They make their nests on high, rocky cliffs because it is very difficult for predators to reach them there. Some seabirds make nests, but others just lay their eggs on a rocky ledge.

 

 

Continue reading "Seashore birds"

 

 

 

At low tide, seashore fish hide. They squeeze into cracks in rock pools or hide under the sand. When the tide comes in, they come out to feed. Seashore fish have eyes near the top of their head. They look out for seabirds that try to catch them from above.

 

 

 

 

 

This fish lives in rock pools.

Goby fish live in rock pools. Their skin is patterned to help them hide against the rocks and seaweed. Some goby fish have their lower fins joined together to make a sucker. They use the sucker to cling on to rocks and stop them from being swept away by waves.

 

 

 

 

These pipefish are hard to see.

Pipefish can hide themselves so well that they are very hard to see. They have a long, thin body that helps to disguise them when they hide in seaweed. They live in rock pools and feed on other small fish and shellfish.

 

 

 

 

This fish can breathe air.

Mudskipper fish live on warm, muddy seashores. Most fish can only breathe in water. Mudskipper fish can breathe in air and water. They use their front fins as legs and crawl about on mud to look for food.

 

 

Some of the animals that we see on seashore do not live there all the time. They spend most of their life in the sea, and only visit the seashore for a short time. They may visit the shore to rest or to have babies.

 

 

 

 

 

 

These seals have come to the shore to rest.

Seals spend most of their time in the sea, but they sometimes visit the seashore. Seals are excellent swimmers but move very slowly on land. They haul themselves up on to rocks or sand banks to rest and bask in the Sun. Seals give birth to their pups on quiet seashores where they will not be disturbed.

 

 

 

 

 

Puffins visit the seashore to nest.

Puffins visit the seashore each year to breed. They nest on the top of cliffs. They dig burrows or take over an old rabbit tunnel. Puffins usually have only one chick. They feed their chicks on sand eels and fish.

 

 

 

 

 

 

Turtles visit the shore to lay their eggs.

Female turtles come ashore at night to lay their eggs above the high tide line. They dig a hole in the sand, lay their eggs in it and cover the eggs with sand. When the babies hatch, they dig themselves out and crawl down to the sea.

 

 

 

Seashores can be harmed by people. If we leave rubbish on a beach, it can hurt or kill wildlife. Plants and animals often lose their homes when we build on the seashore. We all need to take care of the seashore and the wildlife that lives there.

 

 

 

 

 

 

This rubbish has been washed up on a beach.

Rubbish is often dumped in the sea. It can be carried long distances and washed up on beaches. Rubbish like plastic bottles and bags, fishing line and glass can hurt or kill animals. Turtles eat plastic bags because they look like jellyfish.

 

Continue reading "Looking after the seashore"

Rainforests are important to all of us, so we must save them. Many groups of people raise money to protect and restore rainforests. The money might be spent replanting trees or teaching farmers how to look after the forest.

Growing crops in small patches helps to protect the soil.

If local farmers learn to grow their crops in a similar way to the forest people, they can stop the thin soil wearing out. Growing patchworks of different plants and trees, instead of just one type, restores nutrients to the soil. Using the land sustainably means that farmers will not need to move on and cut down more rainforest.

 

 

 

People can visit this protected rainforest.

Some rainforests have been turned into National Parks or reserves where it is against the law to cut down the trees. This helps to keep the animals, plants and people that live there safe. Many tourists visit the parks to see the rainforest wildlife.

 

 

Continue reading "Rescuing the rainforests"

 

 

People who live in rainforests know how to find everything they need. The forest gives them food, shelter, clothes and medicine. In return, they treat the forest with great respect. They take only what they need, without causing any damage.

 

 

 

 

This man is weaving a roof using palm leaves.

Rainforests throughout the world have been home to various tribes of people for thousands of years. They build their homes using rainforest plants and they hunt for meat, gather fruit and nuts and grow useful plants in their gardens. They use the rainforest in a sustainable way that does not destroy it.

 

 

 

 

Rainforest is cleared to make cattle farms.

Many people have moved into rainforests, but they use the forest in ways that destroy it. Huge areas of rainforest have been cut down to make way for farmland. But because the nutrients in the thin soil soon wear out, farmers move on to destroy new parts of the forest, leaving behind a bare, infertile piece of land.

 

 

 

 

This hillside was once covered in trees and packed with wildlife.

When a rainforest is nut down, plants, animals and rainforest people lose their homes. Many species may die out and become extinct. Without the cover of the trees, the thin soil dries up and is washed away by the rain. The land is left like a desert and it is very difficult for rainforest to ever grow there again.

 

Rainforests only cover a small part of the Earth’s surface but they are sometimes called the lungs of the world. They help control the world’s weather and affect the air we breathe.

Rainforests help to recycle gases in the air.

Trees and other plants breathe in the opposite way to humans and animals. Trees breathe in carbon dioxide (which we breathe out) and breathe out oxygen (which we breathe in). This helps to balance gases in the air and ensures there is plenty of oxygen for us to breathe.

 

 

 

Rainforests soak up the heat from the Sun.

Dark green rainforests absorb the heat and strong sunlight that shines in the tropics. When rainforests are cut down and lighter coloured vegetation grows instead, it creates a mirror effect. Sunlight and heat are reflected back up into the atmosphere causing it to warm up.

 

 

 

 

 

 

 

Cutting down rainforests is helping to make the Earth warmer.

When rainforests are destroyed, there are fewer trees to remove carbon dioxide from the air, so it starts to build up. Too much carbon dioxide in the atmosphere traps heat from the Sun like the glass in a greenhouse. This is called the greenhouse effect and it is making the Earth warmer.