Chapter 6 – Animal Classification
1. Identify me.
a. I am diploblastic & acoelomate. Which phylum do I belong to?
Ans: Coelenterata (cnidaria).
b. My body is radially symmetrical. Water vascular system is present in my body. I am referred as fish though I am not. What is my name?
Ans: Jellyfish.
c. I live in your small intestine. Pseudocoelom is present in my thread like body. In which phylum will you include me?
Ans: Aschelminthes.
d. Though I am multicellular, there are no tissues in my body. What is the name of my phylum?
Ans: Phylum Porifera.
2. Write the characters of each of the following animals with the help of classification chart.
Bath sponge, grasshopper, rohu, penguin, frog, lizard, elephant, jellyfish.
(1) Bath Sponge.
Ans:
(i) It belongs to phylum porifera.
(ii) It bears numerous pores on its body called ostia and oscula.
(iii) It has a special type of cell-collar cells.
(iv) It has good regenerative ability.
(v) It is always attached to the substratum and hence does not show locomotion.
(vi) Its body is supported by spicules or spongin fibers.
(2) Grasshopper.
Ans:
(i) Grasshopper belongs to phylum Arthropoda.
(ii) Body is covered with a chitinous exoskeleton.
(iii) Body is divided into the head, thorax and abdomen.
(iv) There are two pairs of wings and three pairs of jointed appendages for locomotion.
(v) It is bilaterally symmetrical.
(3) Rohu
Ans:
(i) Rohu belongs to class pisces.
(ii) It is found in freshwater.
(iii) It is a bony fish.
(iv) Skin shows presence of scales.
(v) Respiration occurs with gills.
(4) Penguin
Ans:
(i) This animal belongs to class Aves.
(ii) They are found at the south pole, i.e. at Antarctica, which is a cold region
(iii) Exoskeleton shows feathers.
(iv) Penguin is warm-blooded.
(v) They are adapted to a cold region life.
(vi) Penguin is oviparous.
(vii) Neck is present between head and trunk.
(5) Frog
Ans:
(i) Frog belongs to class Amphibia.
(ii) Can live in water as well as on land during adult life.
(iii) Skin is without any exoskeleton and is usually kept moist for respiration.
(iv) They have two pairs of appendages. Digits are without claws.
(v) External ear is absent but tympanum (external hearing structure) is present.
(6) Lizard
Ans:
(i) It belongs to class Reptilia.
(ii) It is cold-blooded (Poikilotherm)
(iii) It shows creeping movement as body cannot be
lifted up.
(iv) Neck is present between head and trunk.
(v) External ear is absent.
(7) Elephant
Ans:
(i) Elephants belong to class Mammalia.
(ii) Body shows differentiation into head, neck, trunk and tail.
(iii) Mammary glands are present.
(iv) The heart is four chambered.
(v) Largest terrestrial mammal.
(vi) It is warm-blooded.
(vii) Body is divided into head, neck, trunk and tail.
(8) Jellyfish
Ans:
(i) Jellyfish belong to Phylum Coelenterata.
(ii) Cnidoblast bearing tentacles are present around the mouth. Tentacles are useful for capturing the prey whereas cnidoblasts inject the toxin in the body of the prey.
(iii) Body is umbrella shaped, hence called Medusa.
(iv) It is diploblastic, and shows radial symmetry.
3. Write in brief about progressive changes in animal classification.
Ans:
(i) There are nearly seven million different species of animals which show a lot of diversity. Hence, it is impossible to study them together.
(ii) Many scientists tried to classify animals into various groups.
(iii) Greek philosopher Aristotle was the first to perform animal classification.
(iv) Aristotle classified animals according to criteria like body size, habits and habitats. Classification proposed by Aristotle is known as the ‘Artificial method’.
(v) Besides Aristotle, the ‘Artificial method’ was followed by Theophrastus, Pliny, John Ray, Linnaeus, etc. Later on ‘Natural system of classification’ was followed.
(vi) ‘Natural system of classification’ was based on various criteria like body organization, types of cells, chromosomes, bio-chemical properties etc.
(vii) With time, a system of classification based on evolution was also brought into practice. It was used by Dobzhansky and Meyer.
(viii) Recently, Carl Woese has proposed animal classification. In this way, the classification methods of animals show progressive changes.
4. What is the exact difference between grades of organization and symmetry? Explain with examples.
Ans:
(i) Grades of organization is the structural organization of animals whereas symmetry is whether the animal’s body can be divided into equal halves when cut through an imaginary axis.
(ii) In the grades of organization, unicellular organisms have ‘Protoplasmic grade organization’.
(iii) In multicellular organisms, there are different grades of organization, namely ‘Cellular grade’, ‘Cell-tissue grade’. In some animals, there is ‘Tissue-organ grade organization’, while higher animals have organ system grade organization’.
(iv) Examples:
‘Protoplasmic grade organization’ – Amoeba
Cellular grade organization – Porifera
Cell-tissue grade organization – Cnidarians.
Tissue-organ grade organization – Platyhelminthes.
Organ-system grade organization – All higher animals.
(v) Depending upon symmetry, animals are Asymmetrical, Radially symmetrical and Bilaterally symmetrical.
(vi) Examples:
Asymmetrical – Amoeba
Radially symmetrical – Starfish
Bilateral symmetrical – Cockroach, man.
(vii) Grades of organization are concerned with the structure of animals and this has no relation with symmetry.
5. Answer in brief.
a. Give scientific classification of shark up to class.
Ans: The scientific classification of Shark is:
Kingdom: Animalia
Phylum: Chordata
Sub-phylum: Vertebrata
Class: Chondrichthyes
It belongs to the class Chondrichthyes because its body is formed with cartilages. There is the presence of chondrocytes as well.
b. Write four distinguishing characters of phylum – Echinodermata.
Ans:
(i) Echinodermata have an endoskeleton of calcareous ossicles hence, the name derived as Echinodermata
(ii) The digestive system is complete with the mouth on the lower side and anus on the upper side.
(iii) The most distinctive feature of these organisms is the presence of the water vascular system which helps in locomotion, capture and transport food and respiration.
(iv) The excretory system is absent in echinoderms.
c. Distinguish between butterfly and bat with the help of four distinguishing properties.
Ans:
| Butterfly | Bat |
|---|---|
(i) Butterfly belongs to Non-chordates. | (i) Bats are Chordates. |
(ii) Butterflies belong to Phylum Arthropoda. | (ii) Bat belongs to phylum Chordata. |
(iii) It belongs to Class Insecta. | (iii) It belongs to Class Mammalia. |
(iv) Exoskeleton is chitinous. | (iv) Exoskeleton is covered with hair. |
d. To which phylum does Cockroach belong? Justify your answer with scientific reasons.
Ans:
(i) A cockroach belongs to phylum ‘Arthropoda’.
(ii) A cockroach has jointed appendages.
(iii) Body is divided into the head, thorax and abdomen.
(iv) Two pairs of wings and three pairs of limbs are present for locomotion.
(v) It is bilaterally symmetrical.
(vi) A Cockroach has a pair of antennae which act as sense organs.
(vii) It has a chitinous exoskeleton.
6. Give scientific reasons.
a. Though tortoise lives on land as well as in water, it cannot be included in class – Amphibia.
Ans:
(i) The animals which not only live in water but also on land and respire in both climatic conditions are called Amphibians.
(ii) Tortoise respires through lungs but does not have a structure to respire in water.
(iii) Also, tortoises lay eggs with hard shells which is a characteristic of reptiles.
(iv) Tortoise has a neck, whereas neck is absent in amphibians.
(v) Therefore, tortoises are not amphibians.
b. Our body irritates if it comes in contact with jelly fish.
Ans:
(i) Jellyfish have tentacles with cnidoblasts around their mouths.
(ii) The toxin released from the cnidoblasts comes in contact with the body of a person touching it.
(iii) Due to this, there is an itching effect and irritation.
c. All vertebrates are chordates but all chordates are not vertebrates.
Ans:
(i) In some chordates, the notochord is present only in the tail region of larvae.
(ii) In some other chordates, notochord is present throughout the body length.
(iii) In some chordates, the notochord is replaced by a vertebral column.
(iv) Due to this, all chordates do not get classified in the same group.
(v) Hence, all vertebrates are chordates but all chordates are not vertebrates.
d. Balanoglossus is connecting link between non-chordates & chordates.
Ans:
(i) Balanoglossus belongs to Hemichordata meaning half-chordates.
(ii) The body shows proboscis, collar and trunk.
(iii) Its characteristic features resemble non-chordates as well as chordates.
(iv) Hence, it is considered as a connecting link between non-chordates and chordates.
e. Body temperature of reptiles is not constant.
Ans:
(i) Reptiles are cold blooded animals or poikilotherms.
(ii) The body temperature of cold blooded animals changes with the surrounding temperature.
(iii) Reptilians have different habitats which have different temperatures.
(iv) In order to adapt to different situations, the body temperatures of reptiles at different locations differ.
(v) Hence, their body temperature is not
constant.
7. Answer the following questions by choosing correct option.
a. Which special cells are present in the body of sponges (Porifera)?
(1) Collar cells.
(2) Cnidoblasts.
(3) Germ cells.
(4) Ectodermal cells.
Ans: (1) Collar cells
b. Which of the following animals’ body shows bilateral symmetry?
(1) Star fish.
(2) Jelly fish.
(3) Earthworm.
(4) Sponge.
Ans: (3) Earthworm
c. Which of the following animals can regenerate its broken body part?
(1) Cockroach.
(2) Frog.
(3) Sparrow.
(4) Star fish.
Ans: (4) Star fish
d. Bat is included in which class?
(1) Amphibia.
(2) Reptilia.
(3) Aves.
(4) Mammalia.
Ans: (4) Mammalia
8. Complete the following chart.
| Body cavity Germ layers | Germ layers | Phylum |
|---|---|---|
Absent | __________ | Porifera |
Absent | Triploblastic | __________ |
Pseudocoelom | __________ | Aschelminthes |
Present | __________ | Arthropoda |
Ans:
| Body cavity Germ layers | Germ layers | Phylum |
|---|---|---|
Absent | Diploblastic | Porifera |
Absent | Triploblastic | Platyhelminthes |
Pseudocoelom | Triploblastic | Aschelminthes |
Present | Triploblastic | Arthropoda |
9. Complete the following chart.
| Class | Features | Examples |
|---|---|---|
Cyclostomata | __________ | __________ |
__________ | Gill respiration | __________ |
Amphibia | __________ | __________ |
__________ | __________ | Whale |
__________ | Poikilotherms | __________ |
Ans:
| Class | Features | Examples |
|---|---|---|
Cyclostomata | Jawless mouth | Myxine |
Pisces | Gill respiration | Rohu |
Amphibia | Lay eggs in water, external fertilization | Frog |
Mammalia | Homeotherms, presence of mammary glands | Whale |
Reptilia | Poikilotherms | Lizard |
10. Sketch, label and classify
Hydra, Jellyfish, Planaria, Round worm, Butterfly, Earthworm, Octopus, Star fish, Shark, Frog, Wall lizard, Pigeon.
a. Hydra
Ans:
Kingdom – Animalia
Body organization – Cell tissue
Body symmetry – Radial symmetry
Body cavity – Acoelomate
Phylum – Cnidaria
b. Jellyfish
Ans:
Kingdom – Animalia
Body organization – Cell tissue
Body symmetry – Radial symmetry
Body cavity – Acoelomate
Phylum – Cnidaria
c. Planaria
Ans:
Kingdom – Animalia
Body organization – Tissue grade
Body symmetry – Bilateral symmetry
Body cavity – Acoelomate
Phylum – Platyhelminthes
d. Roundworm
Ans:
Kingdom – Animalia
Body organization – Organ system grade
Body symmetry – Bilateral symmetry
Body cavity – Eucoelomate
Phylum – Annelida
e. Butterfly
Ans:
Kingdom – Animalia
Body organization – Organ system grade
Body symmetry – Bilateral symmetry
Body cavity – Eucoelomate
Phylum – Arthropoda
Phylum – Annelida
f. Earthworm
Ans:
Kingdom – Animalia
Body organization – Organ system grade
Body symmetry – Bilateral symmetry
Body cavity – Eucoelomate
Phylum – Annelida
g. Octopus
Ans:
Kingdom -Animalia
Body organization – Organ system grade
Body symmetry – Bilateral symmetry
Body cavity – Eucoelomate
Phylum – Mollusca
h. Starfish
Ans:
Kingdom – Animalia
Body organization – Organ system grade
Body symmetry – Bilateral symmetry
Body cavity – Eucoelomate
Phylum – Echinodermata
i. Shark
Ans:
Kingdom – Animalia
Body organization – Organ system grade
Body symmetry – Bilateral symmetry
Body cavity – Eucoelomate
Phylum – Pisces
j. Frog
Ans:
Kingdom – Animalia
Body organization – Organ system grade
Body symmetry – Bilateral symmetry
Body cavity – Eucoelomate
Phylum – Amphibia
k. Wall lizard
Ans:
Kingdom – Animalia
Body organization – Organ system grade
Body symmetry – Bilateral symmetry
Body cavity – Eucoelomate
Phylum – Reptilia
l. Pigeon
Ans:
Kingdom – Animalia
Body organization – Organ system grade
Body symmetry – Bilateral symmetry
Body cavity – Eucoelomate
Phylum – Aves
11. Label the following.
Ans:
