SCI6: WORLD OF LIVING THINGS; CLASSIFICATION OF ANIMALS

This unit covers part of Primary Six Science, Term One

CLASSIFICATION OF VERTEBRATES.

Classification of living things (basic characteristics)

  • Classification means grouping of organisms according to their characteristics.
  • Basic characteristics of living things are:
  1. They reproduce.
  2. They respond to stimuli
  3. They respire
  4. They feed
  5. They grow
  6. The excrete
  7. They move/locomote

Groups of animals

  • Animals in the environment are grouped into vertebrates and
  • Vertebrates are animals with a back bone/vertebral column/spine.

Characteristics of vertebrates.

  1. Vertebrates have a back bone
  2. Vertebrates have endo skeleton.
  3. They have a water proof skin.

Classification of vertebrates.

Vertebrates are classified or grouped into two groups namely;

  1. Warm blooded vertebrates
  • Birds
  • Mammals
  1. Cold blooded vertebrates
  • Reptiles
  • Fish
  • Amphibians
  • Warm blooded animals are vertebrates that keep their body temperatures constant or slightly change.

Examples

All birds and mammals

  • Cold blooded animals are vertebrates that change their body temperatures according to the environment.

Examples

Lizards, snakes, crocodiles, frogs, toads and fish

  1. Learners’ Activity List any four characteristics of living things
  2. In one sentence explain the term vertebrates
  3. Identify any one characteristic common to all vertebrates.
  4. Write one sentence to explain the following terms;
  5. Warm blooded animals
  6. Cold blooded animals
  7. Give two examples of cold blooded animals
  8. In one sentence give a reason why animals move.

WARM BLOODED VERTEBRATES

 

BIRDS (CHARACTERISTICS OF BIRDS)

A bird is warm blooded vertebrate covered with feathers, two wings, two legs and a beak.

Characteristics of birds

  • They are warm blooded vertebrates.
  • Their legs are covered with scales and the body with feathers.
  • They reproduce by means of laying eggs which are fertilized internally
  • They breathe using lungs.
  • They are stream lined/pointed at the front and the back to overcome friction (viscosity)
  • They have a four chambered heart.
  • Birds use beaks for pecking food.
  • Birds care for their young ones
  • They have endo skeleton.
  • Birds have back bones

NOTE 1: birds use their front limbs modified as wings for flying and the hind limbs for walking.

An illustration showing the external parts of a bird.

NOTE 2:Their skin is dry, loose and has no sweat glands so cooling is effected by panting

Note 3:

A bird has spurs on the legs for protection/defence.

  • Birds use feathers for protection of the inner body parts from external damage.
  • Feathers of birds provide warmth to the body of the bird.
  • Feathers help the bird to fly especially those of the wings and tail.

TOPIC C: WARM BLOODED  VERTEBRATES

LESSON 3: BIRDS (BIRD FEATHERS) 

 Types of bird feathers;

  • There are basically four types namely;
  1. Quill or flight feathers
  2. Body or covert feathers
  3. Down feathers
  4. Filoplume feathers.

NOTE; Quill feathers are divided into primary and secondary feathers.

  • Quill feathers have a strong central part called the shaft, the hollow portion. They are found on the tail and wings.
  • Covert feathers help to cover the body of the bird
  • Covert feathers are slightly smaller compared to Quill feathers.
  • Filoplume feathers are the smallest and found nearest the skin of the bird.
  • Down feathers help to trap a layer of air close to the body therefore keeping the bird’s body warm.

A Quill feather

 A  covert feather

 

Filo plume feather

 

Below is a diagram of a bird’s feather. Use it to answer the questions that follow.

Image result for diagram of a bird’s feather

  1. Identify the type of feather shown in the diagram
  2. Name parts marked with letters A, B, C, D
  3. In which way is the quill feather useful to a bird?

SUBTOPIC: VERTEBRATES

LESSON 4; BIRDS (REPRODUCTION IN BIRDS)

Content; 

Reproduction in birds

  • Birds reproduce by means of laying eggs.
  • Their eggs are fertilized internally before they are laid out.
  • A hen will sit on the eggs (incubate) until they hatch into young ones (chick)

Parts of an Egg

Functions of the parts.

Egg shell: protects the inner part of an egg.

It is porous to allow free circulation of air.

Air space: keeps and provides oxygen to the embryo.

Egg Yolk; provides carbohydrates/salts, fats to the grown embryo.

Embryo: develops into a chick under favourable conditions.

Albumen; Provides water and mineral salts to the growing embryo.

Chalaza; holds the Yolk and embryo in one position.

SUBTOPIC: VERTEBRATES.

LESSON 5: GROUPS OF BIRDS. (Birds of prey and scavenger birds

 Characteristics of birds of prey

  • Have strong sharp hooked beak for tearing their prey
  • Have strong curved talons for easy gripping of their prey.
  • Have a strong eye sight to locate their prey.

 A Beak of a bird of prey                                                                                      A foot of a bird of prey

 Image result for A Beak of a bird of prey

 

 

 

 

Strong, sharp and hooked beak                                                                             Short curved talons for easy gripping of prey

Scavenger birds.

  • Are birds which feed on flesh killed by other animals
  • Scavenger birds are useful in the environment because they keep the environment clean by eating flesh of dead animals which may rot or smell.

Examples: crows, vultures, marabou storks

Examples of prey; smaller birds; chicks, frogs toads, tortoises/ turtles etc

Dangers of birds of prey to people

They eat people’s chicks, rabbits.

Note: scavenger birds have beaks similar to the birds of prey.

Compare the beaks of a bird of prey and a parrot.

VERTEBRATES

GROUPS OF BIRDS (PERCHING BIRDS, SCRATCHING BIRDS AND CLIMBING BIRDS )

Perching birds:

Image result for Perching birds:

These are birds that perch on branches of trees.

Have one toe pointing backwards and three toes pointing forward

Note: Perching birds are grouped according to their habits and feeding.

These are seed eater, fruit eaters, insect eaters and nectar suckers.

Seed eaters: these have short conical beaks for easy splitting of seeds.

Examples include, pigeons, dove, weaver birds, finches, and parrot.

Insect eaters: These have short narrow beaks for easy picking up of the insects from barks of trees.

Examples include robins, sparrows, swift, swallows. 

Note: Insect eaters have the ability to catch their prey on flight. excel

Content   Nectar suckers; these have long slender beaks for easy sucking of nectar from flowers.

Examples are; the sun bird and humming bird.

An illustration showing a beak of a sun bird.

Fruits eaters: These have long stout beaks for collecting fruits from trees.

  • They are also called foresters and help in seed or fruit disposal.
  • A horn bill is the best example of a fruit eater

 Scratching birds

  • These are birds which scratch earth to find their food.
  • Such birds get worms, small insects and seeds from soil.

Characteristic of scratching birds.

  • They have strong feet with thick toes and blunt talons.
  • They have strong pointed beaks for picking up things from the ground.

An illustration showing a beak and foot of a scratching bird.

Strong foot thick toes and blunt claws                              Strong short pointed beak for picking up food from soil

  

Climbing birds

  • These are birds with two toes pointing forward and two pointing backwards.
  • The toe arrangement helps them to climb trees looking for seeds and insects.
  • They commonly live in trees and run about on branches of trees.

An illustration showing the toes of a climbing bird.

Two toes forward and two toes backwards.

Examples include parrots and wood pecker. They are the best examples of climbing birds.

Learners’ Activity

  1.  In a sentence explain the meaning of the term perching birds
  2. Identify any two characteristics of the perching birds
  3. Give two ways in which perching birds are useful to a crop farmer
  4. In one sentence describe the following groups of perching birds:
  5. Seed eaters
  6. Insect eaters
  • Fruit eaters
  1. Nectar suckers
  2. Give any one example of a nectar sucker
  3. In one sentence describe how perching birds feed.
  4. List the examples of scratching and climbing birds

 VERTEBRATES (BIRDS)

 SWIMMING BIRDS

  • content These are birds with webbed feet for padding in water they swim
  • Examples include, swan, duck, goose, penguin, sea gull, pelican.
  • They have a spoon shaped beak for easy sieving of their food from mud/water.
  • They have a layer of fats to keep them warm in water.
  • They are commonly seen in water looking for their food.

 

VERTEBRATES (BIRDS)

 WADING AND FLIGHTLESS BIRDS

Content

Wading birds;

  • Wading birds are birds that walk through water or wade mainly to find their food.

Wading birds have the following characteristics.

  1. Have long beaks for easy hunting of small fish, frogs and worms from water for food.

Examples of wading birds.

Ibis, heron, eaglet, crested crane, flamingo birds, storks.

  1. Have long thin legs with half webbed toes widely spread out to prevent them from sinking in water.

 

Flightless birds.

  • These are birds which cannot fly but run very fast.
  • Their bodies are heavier compared to the wings hence unable to fly.
  • They have a lot of bone marrow hence heavier to fly in air with their weaker and smaller wings.

Examples of flightless birds includes;

Ostrich, kiwi, emu, penguin, cassowary

Note: ostriches are commonly kept in the zoo and their eggs are edible.

Weak and small wings compared to the body size.

 VERTEBRATES (BIRDS)

 ADAPTATIONS OF BIRDS TO THEIR MODE OF LIFE

Adaptation of birds to their mode of life.

Adaptation means the features that make an organism suit a characteristic or behavior.

Adaptation of birds to their mode of life include:

Their front limbs are modified into wings for easy flight.

  • Most have hollowed bones to reduce their body weight for easy flying.
  • They have a stream lined body to overcome viscosity during flight.
  • They have no pinna to obstruct the flow of air on flight.
  • Their bodies are covered with feathers to provide warmth and colour to the bird.
  • They have a nictitating membrane which protects their eyes against foreign bodies into the eye on flight.

Advantages of birds to people

  • Birds provide people with meat and eggs as food.
  • Some birds such as sun bird help in plant pollination.
  • Some birds (scavengers) help to keep the environment clean
  • Domestic birds are a source of income once sold.

Disadvantages of birds in the environment.

  • Many birds spoil farmer’s crops i.e getting raw materials to make their nests, feed on crops etc.
  • Birds cause noise pollution especially weaver birds in the environment.
  • Bird feathers keep vectors to human health like fleas and mites.

 VERTEBRATES (mammals)

 CHARACTERISTICS OF MAMMALS.

Mammals; These are worm blooded vertebrates whose skin is colored with hair.

General Characteristics of mammals include;

  • They have mammary glands
  • They have well developed ear lobes to trap sound waves.
  • They have fur on their bodies.
  • They breathe through the lungs.
  • They have four chambered hearts.most mammals give birth to their young ones alive except the egg laying mammals
  • They have back bones.
  • All mammals are warm blooded.

Specific characteristics of mammals

  • Their bodies are covered with fur
  • They have mammary glands
  • They feed their young ones on breast milk produced by the mammary glands.

Classification of mammals.

Mammals are grouped into nine sub classes according to their features and behavior.

These are;

  • Primates (most advances mammals)
  • Rodents (gnawing mammals)
  • Ungulates (hoofed mammals)
  • Chiroptera (flying mammals)
  • Monotremes (egg laying mammals)
  • Carnivores (flesh eaters)
  • Marsupials (pouched mammals)
  • Insectivores (insect eating mammals)

 VERTEBRATES (MAMMALS)

 PRIMATES AND MONOTREMES 

Primates (most advanced mammals)

  • Primates are the most advanced subclass of mammals.
  • They have a well developed set of teeth (32)
  • Primates have an advanced brain.

Characteristics of primates.

  • They have five fingers and five toes on each foot.
  • They use their front limbs for holding things while hind limbs for walking.
  • All primates are omnivores feed on both flesh and vegetables)

Examples of primates includes;

People, gorillas, chimpanzee, baboon, bush baby, monkey, apes, gibbon

Drawn structures showing a bush baby, a monkey and a gorilla.

A bush baby

A gorilla

A monkey

Egg – laying mammals (monotremes)

  • These are mammals which reproduce by means of laying eggs.
  • They are also called mammals because they feed their young ones on milk from mammary glands.

Examples of monotremes include;

There are only two examples of monotremes namely; duck billed platypus and spiny anteater (echidna)

 Illustrations showing monotremes

VERTEBRATES (MAMMALS)

FLYING MAMMALS (CHIROPTERA)

 Chiroptera (flying mammals)

  • These are the only mammals that fly.
  • They have fold skin attached to the fore limbs which act as wings. Bats are the only true examples of chiropteras.

There are three types of bats namely;

  • Fruit eaters or foresters.
  • Insect eaters.
  • Blood suckers (vampires)

Note; Bats are nocturnal animals i.e they are more active during the night.

  • Bats use echoes to locate their food at

night and dodge obstacles on flying.

Importance of bats in the environment.

  • Fruit eating bats help in seed dispersal.
  • Insect eating bats help to eat harmful insects in the environment that may cause harm to people such as mosquitoes etc.

Disadvantages of bats.

  • Vampire bats suck blood from animals which may cause anaemia to the animal and even death.
  • Waste materials from bats cause a bad smell in a living house.

An illustration showing a bat flying.

 VERTEBRATES (MAMMALS)

 POUCHED MAMMALS (MARSUPIALS)

 Pouched mammals;

  • These are mammals with pockets on their abdomen inside where mammary glands are found.
  • They are commonly found in Australia and South Africa.

Examples of pouched mammals include;

Kangaroo, koalabear, wallabies, opossums

An illustration showing a kangaroo with its young one.

Note; The word marsupial means a pouch or a bag

  • A kangaroo can leap or jump a great distance.

VERTEBRATES (MAMMALS)

FLESH EATING MAMMALS (CARNIVORES)

Flesh eating mammals (carnivores)

These are sub groups of mammals with well developed canine teeth and feed on flesh.

Characteristics of flesh eating mammals.

  • They have sharp claws for holding, killing and tearing their prey.
  • They have soft pads feet to enable them run after their prey without making noise.
  • They have a good speed, sense of smelling and vision even at night.

Groups of carnivores include;

Carnivores are sub divided into two divisions namely;

  1. Cat family; these have features of the domestic cat.

Examples include; lion, cheetah, leopard, tiger etc.

  1. Dog family; these are carnivores with specific features to that of a domestic dog.

Examples include, domestic dog, hyena. Jackals. Fox etc

An illustration showing the skull of a dog.

Note; Some carnivores are scavenger and therefore feed on flesh killed by other carnivores.

  • Carnivores are also called preying mammals and are predators.

A predator is an animal that hunts and kills its prey.

VERTEBRATES (MAMMALS)

 SEA MAMMALS (CETACEANA)

 Sea mammals;

These are mammals which commonly live in water of seas and oceans.

Characteristics of sea mammals

  • They breathe through the lungs.
  • They reproduce by means of giving birth and feeding their young ones on milk from mammary glands.
  • They have fur on their bodies.

Examples of sea mammals.

Whale, dolphins, porpoise, seals and dugongs.

Note; whales are divided in to two namely, blue whale and sperm whale.

  • A whale is the largest mammal. A whale is over 30m long and over 150 tones in weight .The whale is not a fish.
  • A thin layer of blubber insulates the body against heat loss and it is an important food store.
  • Whales are hunted by people for their high quality oil.

 

Drawn structures showing different examples of sea mammals.

 A whale

Dolphin

Seals

Porpoise

  • Sea mammals have some features similar to that of fish.
  • All sea mammals are vertebrates and are warm blooded.

VERTEBRATES (MAMMALS)

GNAWING MAMMALS (RODENTS)

Gnawing mammals (rodents)

  • These are mammals with well developed incisor teeth and chew rapidly.

Examples of rodents include;

  • Rabbits
  • Rats
  • Squirrels
  • Porcupine
  • Mice
  • Moles
  • Bearers

Characteristic of rodents.

  • They have well developed incisor teeth for biting and chewing rapidly.
  • They don’t have canine teeth.
  • Most gnawing mammals are vegeterians therefore, feed on vegetables.
  • Most rodents are small in size for easy running very fast.
  • Most rodents make holes in soil called burrows for protection and as a habitat.
  • They have sharp strong claws for digging up root crops.

Disadvantages of rodents to crop farmers.

  • All rodents are crop pests.
  • They destroy farmer’s crops by causing damage to them.
  • Some destroy stored harvested crops in the granaries especially the rats..

Drawn structure showing a rat and a squirrel.

A rat

A squirrel

 

VEGETERIANS (MAMMALS)

UNGULATES (HOOFED MAMMALS)

 Ungulates (hoofed mammals)

These are mammals which feed on vegetables and have hooves on their toes.

Characteristics of ungulates or hoofed mammals.

  • They mainly feed on plant materials.
  • They have toes divided into two namely.
  • Even toed , ungulates e.g cow, goat, sheep. Deer, camel etc
  • Odd toed ungulates e.g elephant, horse, zebra, donkey etc.
  • Some ungulates are ruminant and chew cud.
  • Ruminant ungulates have four chambered stomachs.
  • Some ungulates do not chew cud and have one true stomach.

Note: cud is food an animal brings back from the stomach to chew again. This is called rumination. Ruminant animals are animals with four chambered stomachs and chew cud. e.g goats, sheep etc.

Diagram of a ruminant animal

Examples of non- ruminant animals are, hippopotamus, pigs and warthogs.

Drawn structures showing different toes of ungulates.

Elephant

Horse

  

Cow

 

Camel

 

Insectivores.

  • These are mammals that feed on insects.
  • Most of them are nocturnal.

Examples of insectivores include;

-hedgehog – Antbear

-Porcupine – Shrew.

Things to note:

  • A hedge hog stops and hides its head it curls or rolls into a ball for protection.
  • A porcupine has spines for protection.

SUBTOPIC: VERTEBRATES (COLD BLOODED)

LESSON 18: REPTILES (SNAKES)

Reptiles.

  • Reptiles are animals which move by crawling
  • The word reptile comes from reptalia meaning crawlers.
  • Reptiles commonly live in warm countries.

Characteristics of reptiles.

  • All reptiles are cold blooded (poikilothermic)
  • Reptiles breathe through their lungs.
  • They reproduce by means of laying eggs fertilized internally.
  • All reptiles have their bodies covered with scales.
  • They have three chambered heart i.e two atria and one ventrical.

Groups of reptiles.

The main groups of reptiles include , snakes, lizards, tortoises, alligators, crocodiles.

Snakes.

  • Snakes are groups of reptiles with no limbs and move by gliding/slithering/crawling caused by contraction of their muscles.
  • They moult to grow a new skin and increase in size.
  • They have a forked tongue which acts as a sense organ for smell and touch.
  • Snakes commonly move with their tongues out for protection and easy trapping of its prey.
  • Snakes are carnivorous animals.

Diagrams of different snakes

 

Note; Moulting is the removal of the outer old skin to allow the snake grow a new skin and increase in size.

Classification of snakes;

Snakes are grouped or classified according to their features and adaptations

There are basically three groups of snakes. These are;

  • Poisonous snakes
  • Non-poisonous snakes

COLD BLOOD VERTEBRATES (REPTILES)

POISONOUS AND NON-POISONOUS SNAKES.

 Poisonous snakes;

  • These are groups of snakes with poison glands and fangs.
  • They have a pair of long hollow teeth (fangs) connected to the poison glands.
  • When snakes bite, they inject their poison in the bitten area of the animal. This poison from snakes is called venom.
  • Snake venom can be used to make serum used for providing treatment against snake bites.

Effect of snake poison on blood.

  • Venom lowers the temperature of blood thus clotting it, once clotted, the part affected is cut off (amputated).

Diagram show a head of a poisonous snake

Note: each type of a poisonous snake has different types of venom.

Some snakes have their poison gland situated at the back on the mouth with others near the front part of the mouth.

First aid for snake bites.

  • Calm the casualty
  • Identify the fang marks.
  • Tie slightly above the bitten part.
  • Take the casualty to the nearest health unit.


Examples of poisonous snakes.

Cobra, black mamba, puff udder, Gabon viper

Non-poisonous snakes.

  • These are groups of snakes with fangs with no venom.
  • They kill their prey by suffocating them to death

Examples; Green snakes, brown house snake.

Note; Non-poisonous snakes help to feed on other organisms such as fogs, rats and mice.

  • Constrictors are snakes with developed fangs.
  • They kill their prey by crushing and suffocating them.
  • They lick their prey making it slippery for easy swallowing.

Examples include; pythons, anaconda, boa.

Note: the jaws of a snake are specially constructed to enable them to swallow their prey much larger than their width.

 COLD VERTEBRATES (REPTILES)

 CROCODILES AND ALLIGATORS.

  Crocodiles and alligators.

  • Crocodiles are the largest reptiles.
  • They are very lazy and lethargic
  • They have a long strong jaw for feeding on some aquatic animals.
  • They have a long powerful tail for swimming and attacking their prey.
  • The female lay hard-shelled eggs in sand or mud.
  • Alligators have similar features to the crocodiles however, they live in big waters.

An illustration showing a crocodile.

Tortoises and Turtles/Terrapins.

 Tortoises are reptiles enclosed in a complete hard shell made of bony plates.

  • They do not have teeth but have sharp cutting edges for proper digestion of their food.
  • They withdraw and hide in their hard shell incase of danger.
  • Turtles have flippers for easy swimming in water
  • All tortoises/terrapins and turtles use lungs for breathing.
  • They reproduce by means of laying eggs commonly laid in sand.
  • Tortoises commonly live on land while turtles live in muddy waters.

Structure showing a tortoise and a turtle.

A tortoise with hard shell

Turtle with flipper for swimming

OLYMPUS DIGITAL CAMERA

 

Note; some tortoise eat plants while others eat small insects. 

 COLD BLOODED VERTEBRATES (REPTILES)

LIZARDS AND CHAMELEONS

Lizards:

Lizards have two pairs of limbs i.e front and hind limbs for movements.

Groups of lizards include:

Common lizards, geckoes and chameleons.

Characteristics of lizards.

  • They have a fleshy forked tongue for easy trapping of their prey.
  • They have movable eye lids.
  • They moult to grow new skins and increase in size.
  • Geckoes are commonly found in houses and move up side down the ceilings.
  • They have suction pads on their feet to enable them walk upside down the ceilings.
  • A chameleon has building eyes close to the top of its head to see in all directions back, sideways and forward)
  • Chameleons feed on insects such as mosquitoes, house flies using its sticky forked tongue.
  • Chameleons camouflage to protect themselves from enemies and easy location of their food.

Diagrams of a common lizard and chameleon  

 Common Lizard

 Chameleon

 

Importance of reptiles.

  • Some reptiles are sources of food to some people.
  • Snakes provide skins for making leather.
  • Reptiles attract tourists from other foreign countries.
  • Reptiles help to eat harmful insects in the environment.

COLD BLOODED VERTEBRATES(AMPHIBIANS)

 CHARACTERISTICS OF AMPHIBIANS. 

 Amphibians;

  • Are cold blooded vertebrates that live both on land and in water.
  • Amphibians are adapted for early life on water and later life on land.

Examples of amphibians.

These include toads, newts, frogs and salamander.

Characteristics of amphibians.

  • On land they use lungs while in water they use moist skin to breathe.
  • They live both on land and in water.
  • All amphibians are cold blooded animals (poikilothermic)
  • They reproduce by means of laying eggs fertilized externally.
  • They have webbed feet for easy swimming in water.
  • Their young ones called tadpole have a tail and breathe through gills like fish.
  • A newt and a salamander have tails compared to a frog and a toad.
  • They have back bones.

 A structure showing external features of a toad.

Differences between a frog and a toad

  

 Frog: Lay eggs in big masses (cluster) batches

 Toad: Lay eggs in a double ribbon like structure called spawn.

Frog: Breathes through their moist skin and the lungs

 Toad:Breathes through lungs only

 Frog:Commonly live in water at late stages.

 Toad:Commonly live in water at early stages and on land at late stages.

Frog:Have long flexible hind legs to make long jumps

Toad:Have short hind legs and make short jumps

A frog: has a smooth shinny skin with no poison glands.

A toad: has a rough warty skin with poison glands

 COLD BLOODED VERTEBRATES (AMPHIBIANS)

RESPIRATION IN AMPHIBIANS 

How amphibians respire.

  • A frog breathes through its moist skin and mouth cavity in water and lungs for breathing on land.
  • A frog keeps its skin moist by secretions from the mucus glands.
  • A toad also uses lungs and mouth cavity for breathing.
  • Amphibians do not have diaphragms and ribs.
  • A tadpole uses external gills for breathing.

Movement;

  • The hind limbs of amphibians are used for crawling and leaping.
  • The front legs of amphibians are used for absorbing pressure of the shock of landing.

Feeding;

  • Adult frogs and toads are carnivorous as they feed on worms, beetles, cockroaches, houseflies and other insects.
  • Sometimes toads and frogs leap towards an insect and trap it using their sticky tongues.
  • A tadpole is herbivorous and feeds on plants in water.

Note: Toads and frogs hibernate, a state when the body activities are slowed down e.g feeding. This is also called Aestivation.

 Adaptations of a frog to living in water.

  • Frogs have streamlined bodies to enable them move easily in water.
  • Frogs have fully webbed hind feet for swimming in water.
  • Frogs use their skins and mouth cavity for breathing while in water.
  • Frogs can close nostrils when under water to prevent water from entering into the body.

COLD BLOODED VERTEBRATES (FISH)

CHARACTERISTICS OF FISH 

Fish.

Characteristics of fish;

  • They reproduce by means of laying eggs fertilized externally on water.
  • They use their fins for swimming in water.
  • They are cold blooded vertebrates and breathe in dissolved oxygen in water using gills.
  • A young fish is called a fry.

An illustration showing the external parts of a fish.

Functions of the parts.

Scales – covers the body of the fish.

Gill cover – Protect the gills from external damage. Its also called operculum

Nostril – for smelling and tasting food.

Tail fin – For steering on swimming or changing directions.

  • It’s also called the caudal fin.

Dorsal fin – for protection against predators/defence.

Pectoral and pelvic fins. – For slowing down or stopping or act as brakes during swimming.

Mouth; is a passage of food and water with dissolved oxygen to the gills.

Lateral line – detects sound waves in water.

COLD BLOODED VERTEBRATES (FISH)

 TYPES OF FISH

Types of fish.

There are basically three types of fish namely;

  • Bony fish
  • Cartilaginous fish
  • Lung fish

Bony fish.

These are fishes with a bony skeleton and covered with overlapping scales.

Examples include;

Tilapia, nile perch, herrings, Solomon fish.

Cartilaginous fish

These are fish with no true bones but just soft bones called the cartilage.

They do not have a swim bladder and gill covers.

Examples of cartilaginous fish are;

Shark, dog fish, rays, skates.

Lung fish;

These are fish commonly found in dirty waters of pools, Swamps and rivers.

The commonly hibernate during the dry season and continue living in wet season.

Examples of lung fish include;

Emmamba, epiceratodus, are the common examples of lung fish.

Diagrams showing different types of fish  

Bony fish

 

Cartilaginous fish

 

Lung fish

Reproduction in fish.

  • Female fish lay eggs in shallow water where the male sheds sperm over them.
  • Fish undergo external fertilization.

Many eggs are laid but only a few hatch and develop into adults.

Note; most fish do not take care of their young one except the tilapia fish.

 COLD BLOODED VERTEBRATES (FISH)

BREATHING OF THE FISH.

  Breathing system of a fish.

  • Fish breathe in dissolved oxygen using gills.
  • Dissolved oxygen in water is allowed to enter through the mouth cavity and trapped by the gill filament.
  • Gill rakes help to trap any foreign body that enters with water to avoid damaging the filaments.
  • Gill bar helps to hold the gill filament.
  • Gaseous exchange takes place in the gill filament.
  • A fish has a number of gill filaments to increase the surface area for respiration (intake of oxygen).

Note: A fish will die shortly in case it is removed from water due to lack of dissolved oxygen.

An illustration showing parts of the gills.

 

 

Adaptations of the fish to living in water.

  • Fish use gills for breathing.
  • They are stream lined for easily swimming in water.
  • Fish use swim bladder for buoyancy in water.
  • Some fish are slippery to escape easy from their enemies.
  • Fish have lateral line to detect sound waves in water.
  • They have fins for easy swimming in water.

 INVERTEBRATES

GROUPS OF INVERTEBRATES (Coelenterates, sponges and echinoderms) 

Invertebrates;

  • These are animals with no back bone or vertebral column/spine.
  • Most have got an exo-skeleton and do moult.

Groups of invertebrates

These are basically six groups of invertebrates namely;

Coelenterates, molluscs, Echinoderms and sponges, worms and Arthropods.

Coelenterates.

  • These are stinging animals with one body opening.
  • Their opening works as both the mouth and Anus surrounded by tentacles.

Examples of coelenterates includes;

Hydra,  jerry fish, sea anemones and corals

Echinoderms and sponges

  • These are animals which live in seas.

Examples include, star fish, sea urchin and sea cucumbers

An illustration showing a star fish

  • Sponges also live in fresh water and commonly live in colonies.
  • They breathe and feed through many holes on their bodies.
  • Food and oxygen are absorbed as water flows through their holes on the body.

INVERTEBRATES.

MOLLUSCS.

  Molluscs;

These are invertebrates which are soft bodied and usually protected by a shell.

They live in shells in seas and other fresh water bodies. Some of them live on land.

Examples of molluscs.

Oyster, octopus, cuttlefish, garden snail, water snail, slugs, squids.

  • The garden snail and slugs live on land.
  • They have tentacles for detecting sound, smell and temperature.
  • Sea molluscs have gills for breathing while land molluscs use simple lungs.

Illustrations showing different examples of molluscs

Slug

Garden snail

Garden Snail

oyster

Octopus

Dangers of molluscs to people.

  • Fresh water molluscs are vectors to people.
  • They spread worms that cause bilharzia.
  • This worm is called schistosome.

INVERTEBRATES (WORMS)

SEGMENTED WORMS.

 Worms;

  • These are long thin and soft bodied invertebrates.
  • They use their moist skins for breathing.
  • They have hydrostatic type of skeleton.

Categories of worms

  • worms are grouped into three major groups namely:
  • segmented worm (annelids)
  • round worms (nematodes)
  • flat worms.

Segmented worm:

These are worms with segmented bodied or rings. they mostly live in most places.

Examples of segmented worms include:

An earthworm, bristle worm and leech.

Earth worms feed on plant materials.

Below are diagrams showing an earthworm and a leech

Earthworm

Leech

Note; An earthworm is a hermaphrodite. i.e have both female and male reproductive organs.

  • Earth worms help in aeration of soil as they make channels in the soil.
  • Earth worms come out of the soil when it has rained to breath in oxygen.
  • Earth worms also soften the soil.
  • Their excreta help in the formation of humus sub-groups

How earthworms move.

Earth worm move by contraction of their body muscles.

INVERTEBRATES(WORMS)

FLAT WORMS. 

Flat worms:

  • These are worms with flattened and segmented bodies made up of three layers.
  • They are parasites to animals and live in the animals’ intestine.
  • They feed on animals digested food. 

Examples of flat worms.

  • Tape worm, liver flukes.
  • tape worms live in the small intestines in animals and feed on the digested food
  • They have the hooks to attach themselves on the walls of the stomach.
  • They have the suckers for sucking digested food from the stomach walls.
  • Their bodies are covered with mucus to prevent themselves from hot substances sent to the stomach.
  • Liver flukes are paper like and live in the liver of the affected animal causing damage to it.

Diagram showing parts of a tape worm.

 INVERTEBRATES.

ROUND WORMS 

round worms

  • These are groups of worms with a cylindrical body.
  • They are also parasites to animals and people.
  • Some live in water and others in soil.
  • The commonest type of round worms lives in animal’s small intestine and usually seen through faeces of infected animals.

Examples of round worms

  • hook worms
  • pin worms
  • guinea worms
  • ascaris worms
  • filatial worms
  • eel worms
  • Thread worms.

How hook worms enter our body?

  • by penetrating through soles of our feet when we walk bare-footed, especially in dirty places.
  • they enter through the skin and stay in the small intestine sucking blood.
  • as they suck blood, they cause anaemia to the host. 

a diagram of a hookworm

 Dangers of worms to people

  • They suck blood hence causing anaemia.

Ways of preventing hook worm infection

  • By wearing scandals/shoes when visiting dump places such as latrines.
  • By washing hands after visiting a latrine.
  • By washing fruits before eating them in raw form.
  • Through proper disposal of human wastes.

 INVERTEBRATES

 SINGLE-CELLED INVERTEBRATES 

Single celled animals:

  • These are very tiny (microscopic) animals whose bodies are made up of a cell-membrane, cytoplasm and a nucleus.
  • They are also known as unicellular organisms.
  • Such single-celled animals are called protozoa.
  • Many of them are found living in ponds, ditches, seas, lakes, rivers and inside bodies of other animals.
  • They are too small to seen by our naked eyes. Therefore they are observed through an instrument called microscope.

Examples of Single-Celled Animals

  • Amoeba
  • paramecium
  • plasmodia
  • Chlamydia
  • trypanosomes
  • schistosomes etc.

Structures of an Amoeba and Paramecium

amoeba

paramecium

Characteristics of an amoeba.

  • They live in water to protect them against drying up.
  • They reproduce by cell-division.
  • They feed by engulfing food particles.
  • They move by means of pseudopodia (false legs).
  • They are single-celled-unicellular in nature.

Characteristic of a Paramecium.

  • It is a unicellular organism.
  • It has a nucleus, cell membrane and cytoplasm.
  • It moves by means of cilia.
  • It also reproduces by cell-division.
  • Its body is covered by cilia.

Dangers of Protozoa.

  • Most protozoa cause diseases to people. e.g.
  • Amoeba- amoebic dysentery.
  • plasmodia- malaria
  • Chlamydia- bilharzias
  • Trypanosomes- sleeping sickness to people and nagana to live stock. 

INVERTEBRATES (Arthropods)

 Groups arthropods (myriapods) 

Arthropods:

These are animals with jointed legs and segmented bodies.

  • Their bodies are covered with an exo-skeleton.
  • The exo skeleton controls their growth and size.
  • Arthropods do moult to remove their exo-skeleton in order to grow a new one and increase in size.

Sub groups of arthropods.

Arthropods are sub divided into four sub groups. myriapods, arachnids, crustaceans, insects.

Myriapods;

Myriapods are arthropods with many jointed legs with an exo-skeleton.

Examples of myriapods include millipedes and centipedes.

Diagram showing a centipede and millipede.

Centipede

Millipede

   

 

A centipede has one pair of jointed legs on each segment.

  • A centipede is a carnivore and feeds on insects and other small worms.
  • A centipede has poison glands which produce poison used to inject in its prey and for protection.
  • A millipede is a herbivore and makes holes in soil hence helping in soil aeration.
  • A millipede protects itself from enemies by curving up into a ball like structure/by coiling.
  • Some small millipedes produce a smelly fluid for protection.
  • They also roll on their backs when disturbed to scare their enemies

Similarities between centipedes and millipedes

  • Both have jointed legs on each segment
  • Both have an exoskeleton
  • Both roll on their backs when disturbed to scare their enemies

Differences between centipedes and millipedes

  • A centipede is a carnivore while a millipede is a herbivore
  • Unlike a centipede a millipede has more legs
  • A centipede has poison glands for protection while a millipede protects itself by coiling

 INVERTEBRATES (Anthropods)

 Groups of arthropods (arachnids) 

Arachnids

  • These are arthropods which have four pairs of legs.

Characteristics of arachnids.

  1. Have no antennae.
  2. Have two main body parts (head and abdomen).
  3. Have four pairs of legs – eight legs.
  4. Have a simple eye and also compound eyes.

Examples of arachnids include

Ticks, scorpions and spiders.

Spiders

  • Spiders are commonly seen on walls of houses.
  • They use book lungs for breathing
  • They make webs for their nests and also for trapping prey.
  • Spiders are carnivorous, trap small insects and suck their fluids for food.
  • The males also use the web to trap the females for mating.

Reasons why spiders are not classified as insects.

  • They have two main body parts instead of three
  • Spiders have for pairs of jointed legs instead of three.
  • Spiders use book lungs for breathing while insects use spiracles. 

Scorpion

  • A scorpion has a large tail with poison which it injects into its enemies after stinging them.
  • A scorpion produces live young ones.

Ticks

Ticks suck blood from animal hence spreading tick borne diseases to animals.

Examples of tick borne disease include:

East coast fever, red water, heart water, anaplasmosis.

They are all caused by protozoa spread by ticks to cattle.

Note:

Tick borne diseases can be controlled on the farm by:

  • Dipping and spraying the animals with acaricides.
  • Grazing animals on new pasture.
  • By double fencing (best method).

Drawn structures showing a tick, spider, scorpion and a mite.

tick

Mite

    

 

Learners activity

  1. What are arachnids?
  2. List any two characteristics of arachnids.
  3. Give two reasons why spiders are not classified as insects
  4. Give two examples of tick borne diseases
  5. In two sentences, state how a farmer can control spread of tick borne diseases on a farm.

 

INVERTEBRATES (Insects)

Characteristics of insects.

Insects

  • These are arthropods with three main body parts.
  • They have three pairs of joined legs
  • Insects breathe through organs called spiracles located on their abdomen.
  • Have one pair of antennae/feelers
  • Insects have an exo-skeleton and do moult. 

Examples of insects:

  • Houseflies, tse-tse flies, dragon flies, grasshoppers, cockroaches, moth, bees etc.

External parts of a housefly.

Image result for External parts of a housefly.

Function of the above parts.

  1. Compound eyes: used for vision or sight.
  2. Antennae: for smelling and feeling.
  3. Proboscis: for sucking food or fluids.
  4. Mandibles: for chewing its food.
  5. Wings: for flying.
  6. Halteres: for balancing in air while flying.
  7. Spiracles: for gaseous exchange/breathing.

Importance of the thorax to the insect

  • Provides attachment of wings.
  • Is where wings and jointed legs are attached
  • Has halteres used by the insect to balance in air during flight.

Learners activity

  1. List down four characteristics of insects
  2. State the function of the following parts of an insect;

i]. antennae  ii]. Spiracles iii]. Halters

  1. In the space below, show the life cycle of a house fly (diagram)
  2. What name if given to the larva of a mosquito?
  3. Explain the following terms;

i]. metamorphosis  ii]. Moulting

iii]. Incomplete  metamorphosis

 INVERTEBRATES (insects)

Reproduction in insects. 

Reproduction in insects

  • most insects reproduce by means of laying eggs.
  • there are basically two types of metamorphosis namely complete metamorphosis and incomplete metamorphosis.

Complete metamorphosis

This is a type of metamorphosis (complete life cycle) in which an insect undergoes four distinct stages of development.

These include eggs, larva, pupa and adult.

Note: the larva stage of a housefly is the most active stage while the pupa stage is the most dormant stage

The larva stage of the following insects ;

  • housefly-maggots
  • mosquito-wrigglers
  • butterflies-caterpillar
  • cockroach-nymph

A diagram showing a complete metamorphosis of a housefly.

A diagram showing a complete metamorphosis of a anopheles and culex mosquito.

Image result for metamorphosis of a anopheles and culex mosquito

Examples of insects that undergo complete life cycles

Houseflies, mosquitoes, bees, wasps, butterflies, moth.

Incomplete metamorphosis.

  • This is type of life cycle in which insects undergo three stages of development.

A diagram showing incomplete metamorphosis of a cockroach

Examples of insects which undergo incomplete metamorphosis, cockroaches, grasshoppers, locusts.

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ASSIGNMENT : WORLD OF LIVING THINGS assignment MARKS : 10  DURATION : 1 week, 3 days

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