Classification of Animals Class 7 Biology

Selina Concise ICSE Solutions for Class 7 Biology Chapter 3 Classification of Animals

Synopsis

•  The animals can move from one place to another in search of food and shelter and this is called locomotion.
•  The vertebrates can be classified into five classes:
  1.  Pisces (Fishes)
  2.  Amphibia (Frogs)
  3.  Reptilia (Lizards and Snakes)
  4.  Aves (Birds)
  5. (Mammalia (Milk – nourishing animals)
• Pisces / Fishes
  1.  have streamlined body shape
  2.  Locomotion with the help of fins
  3.  Body covered with scales.
  4.  Breathe through gills.
  5. Example: Dogfish, Catla
•  Amphibia / Frogs
  1.  can live in water as well as on land.
  2. always lay their eggs in water.
  3. body covered by a slimy and slippery skin
  4. breathe through lungs and skin.
  5. Example: Frog and toads.
•  Reptilia
  1.  Mostly live on land
  2.  Skin is dry and scaly
  3.  Breathe through lungs
  4. Females lay eggs on land
  5. Example: Lizards, snakes, crocodiles
• Aves / Birds
  1. Body covered with feathers.
  2. Have wings to fly.
  3. Scales only on legs.
  4. Have jaws with homy beak and have no teeth.
  5. Example: Pigeon, hen
• Mammalia / Milk – nourishing animals.
  1. Body covered with hairs.
  2. Posses projecting external ears.
  3. Give birth to young ones.
  4. Mothers suckle their young ones.
  5. Have a tail and four limbs. (Tail may become vestigeal)
  6. Example: dog, tiger, man.
• Invertebrates can be further divided into nine groups.
  1. Protozoans
  2. Porifera
  3. Coelenterates
  4. platyhelminths
  5. Nemathelminths
  6. Annelids
  7. Molluscs
  8. Arthropoda
  9. Echinoderms
• Coelenterates
  1. Now called cnidarians
  2. Body is tube like with only one opening called the mouth.
  3. Mouth is surrounded by finger like processes called tentacles for catching food.
  4. Body radially symmetrical
  5. Example: Hydra, Sea-anemone, jelly fish
• Flatworms / Platyhelminths:
  are usually found as parasites in the bodies of other animals.
  Example: Tapeworm, liver fluke.
•  Ascaris: The round worm is found in the small intestine of especially those who eat with the unwashed hands.
•  Annelids:
  1.  are also called segmented worms
  2.  body is composed of rings or segments
  3.  have a body cavity.
  4. have special organs of excretion called nephridia.
     Example: earthworm, leech.
•  Arthropods can be further divided into
  1.  Crustacea : head and thorax are fused and have many jointed legs.
     Example: crab, lobsters etc.
  2.  Myriagoda: Body is divided into many segments and has one or two pairs of legs on each segment.
     Example: Centipede, millipede.
•  Insecta: Body is divided into three regions – head, thorax and abdomen.
  — Has three pairs of legs.
  — Have two pairs of wings.
  Example: ant, housefly, butterfly.
•  Arachnida: Head and thorax fused
  — Have four pairs of legs.
  — Have no wings.
  Example: Spider, Scorpion
•  Echinoderms
  — also called spiny-skinned animals.
  — Body is star – like or ball – like
  — Have no head or tail.
  — Have no left or right side.
  Example: Starfish, sea urchin.
• A species can be defined as a group of individuals having common characteristics and which come together to pro¬duce young ones.
•  Scientific name consists of two parts. The first part is the genus name while the second part is the species name.
  This type of naming is called Binomial nomenclature.
• The animals can be classified also on the basis of their food habits into as follows.
  (a) Herbivorous:Feed on plants e.g. cow, goat.
  (b) Carnivorous:Feed on the flesh of other animals  e.g. lion, tiger etc.
  (c) Omnivorous:Feed on both plants as well as flesh of other animals, e.g. man, bear etc.
  (d) Parasites:Live either inside or on the outside of the body of other animals and plants and take food from them.
  Example: Leech, mosquitoes etc.

Activity 3
Look at the four animals shown alongside.
Which four classes of vertebrates are represented by them ? Name these classes.

Answer:
1. Class Mammalia
2. Class Mammalia
3. Class Reptilia
4. Class Pisces

Review Questions

MULTIPLE CHOICE QUESTIONS

1. Tick (✓) the appropriate answer:

(i) Identify the aquatic animal with scaly skin which breathe with gills –
(a) Rohu
(b) Tortoise
(c) Sparrow
(d) Rat

(ii) The unicellular organism causing malaria –
(a) Amoeba
(b) Paramecium
(c) Euglena
(d) Plasmodium

(iii) Identify the animal which is not an Arthropoda —
(a) Prawn
(b) Butterfly
(c) Earthwonn
(d) Spider

(iv) Scientist who introduced binomial nomenclature is —
(a) Charles Darwin
(b) Carolus Linnaeus
(c) Robert Hooke
(d) Gregor Mendel

Short Answer Questions
1. Give two examples of each of the following:
(i) Amphibians:
Ans. Amphibians: 1. Frog 2. Toad
(ii) Segmented worms:
Ans. Segmented worms: 1. Earthworm 2. Leech
(iii) Reptiles:
Ans. Reptiles: 1. Snake 2. Lizard
(iv) Coelenterates:
Ans. Coelenterates : 1. Hydra 2. Jellyfish
(v) Arthropods:
Ans. Arthropods: 1. Crab 2. Centipede
(vi) Flatworms:
Ans. Flatworms: 1. Tapeworm 2. Liverfluke

2. Give names of two animals which are found as parasites inside the human intestine.
Ans. (a) Tapeworm (b)Ascaris ’

3. Name one example each of an animal which shows the following characteristics:
(i) Fixed animals with a pore-bearing body:
Ans. Fixed animals with a pore-bearing body: sponge
(ii) Star-shaped body:
Ans. Star-shaped body: Star-fish
(iii) Can live in water as well as on land:
Ans. Can live in water as well as on land: Frog
(iv) Has a flattened ribbon-like body:
Ans. Has a flattened ribbon-like body: Tapeworm

4. Write one difference each between the following pairs:
(i) Porifera and Coelenterata.
(ii) Arthropoda and mollusca.
(iii) Invertebrates and Vertebrates
(iv) Platyheminthes and Nematoda
Answer:
(i) Porifera and Coelenterata.
Porifera

1.  Body is porous i. e. bears many tiny pores to draw water into the body cavity.
2.  e.g. Sponge

Coelenterata

1. Sac-like body with only one opening i.e. mouth.
2. e.g. Jelly fish, hydra,sea-anemone.

(ii) Arthropoda and mollusca.
Arthropoda 

1.  These are animals with
2.  They have segmented body.
3.  They may or may not have wings
   Example: Crab.

Mollusca

1.  Move with the help of a muscular foot.
2.  Soft body which is not segmented.
3.  Body enclosed in a hard shell Example: Octopus

(iii) Invertebrates and Vertebrates

Invertebrates

1.  The animals which do not have a back bone.
2.  They are further classified into nine groups.
   Example: Octopus, Starfish.

Vertebrates

1.  The animals which have a back bone or a vertebral column.
2.  They are further classified in to five groups.
   Example: Human Being, Lizard.

(iv) Platyheminthes and Nematoda
Platyheminthes

1.  Body thin and flattened.
2.  Mostly live as parasites in the bodies of other animals (hosts)
   e.g. Tapeworm.

Nematoda

1. Body is rounded and unsegmented.
2. Mostly live as parasites in the body of animals including humans.
   e.g. Roundworm commonly called Ascaris.

5. Match the animals given under column A with their respective classification group given under column B –

Column A                                          Column B


Answer:

  

6. Write the characteristics of class Aves with reference to their body covering and jaws.
Answer:
The characteristics of class Aves are:

1.  Body is covered with feathers.
2.  They have wings to aid flying
3.  They have scales on legs.
4.  They have no teeth.
5. They have jaws provided with homy beaks

7. Categorise the following animals under their appropriate columns of classification.

Answer:
Worms – Arthropods, Butterfly, Ascaris, Scorpion, Honey bee, Liverfluke, Leech, grasshopper, Eathworm
Molluscs – Snail
Fishes – Rohu
Amphibians – Toad, Frog
Reptiles – Snake, Lizard, Turtle
Birds – Parrot, Pigeon
Mammals – Rat, Bat, Dog, Cattle, Cow, Rabbit, Monkey, Elephant