Each animal is drawn in the layer of the forest it actually uses , and that layer is itself a clue to how it is built. Where Animals seen there Feature that fits the place Flying high in the air Eagle, bats Wings; hollow bones in the bird, wing membranes in the bat Flying near the ground Butterflies, dragonfly, fireflies, small birds Small light bodies; the firefly makes its own light On trees / branches Langur, lion-tailed macaque, slow loris, owl, python, perching birds Gripping hands and feet, claws, a long balancing tail On the forest floor Tiger, leopard, sloth bear, deer, porcupine, civet, hare, peacock Strong limbs for walking and running; quills or camouflage for defence In or near water Crocodile, frog Streamlined body and webbed feet; moist skin in the frog Why record this: "where does it live" is the criterion Aristotle used in the 4th century BCE. It is easy to observe, but you will see in section 12.5 exactly why it failed — a bat and an eagle both fly, yet a bat is a mammal that feeds its young on milk.

NCERT Solutions for Class 9th Science Chapter 12 Let us compare and classify — Activity 12.1

Book page 230 – 231 Updated on2026-09-08

Q1.

Fig. 12.2 shows the diversity of animals in an ecosystem. Observe the image carefully. Can you guess how the organisms are grouped in the image?

Answer

The picture is split down the middle by time of day, not by kind of animal. The left half is the same forest in daylight and the right half is the same forest at night, so the artist has grouped the animals by when they are active — day-active (diurnal) on the lit side, night-active (nocturnal) on the dark side.

How you can tell: look for animals that are obviously built for one or the other.

On the lit side — peacock, eagle in flight, spotted deer, leopard, tiger, sloth bear, langur, lion-tailed macaque, butterfly, dragonfly, small perching birds, a hare at the water's edge. All hunt or feed by sight in daylight.
On the dark side — bats, an owl on a branch, a python coiled on a bough, a slow loris with huge eyes, a porcupine, a civet, a crocodile in the water, fireflies. Large eyes, keen hearing and glowing signals are night equipment.

The habitat also groups them vertically — canopy, tree trunk, forest floor, water — but the day/night split is the one the caption names: Day and night view of an ecosystem.

Check it yourself: the same forest is shown twice, so any animal you can find on both halves is active during the day and the night. That is what part (iii) of the next question is after.

Q2.

Which animals can you identify in the given picture?

Answer

Reading Fig. 12.2 at full size, the animals shown are:

Group	Animals in Fig. 12.2
Mammals	Tiger, leopard, sloth bear, spotted deer (chital), langur, lion-tailed macaque, slow loris, porcupine, civet, bats, hare
Birds	Peacock, eagle, owl, small perching birds
Reptiles	Python (on a branch), crocodile in the stream
Amphibian	Frog near the water's edge
Insects and other arthropods	Butterflies, dragonfly, fireflies

Note: your own list may differ slightly — a picture is read, not measured. What matters is that you record what you actually see, exactly as a field biologist records a survey. Add anything you can identify that is not in the table above.

Q3.

Where are they seen?

Answer

Each animal is drawn in the layer of the forest it actually uses, and that layer is itself a clue to how it is built.

Where	Animals seen there	Feature that fits the place
Flying high in the air	Eagle, bats	Wings; hollow bones in the bird, wing membranes in the bat
Flying near the ground	Butterflies, dragonfly, fireflies, small birds	Small light bodies; the firefly makes its own light
On trees / branches	Langur, lion-tailed macaque, slow loris, owl, python, perching birds	Gripping hands and feet, claws, a long balancing tail
On the forest floor	Tiger, leopard, sloth bear, deer, porcupine, civet, hare, peacock	Strong limbs for walking and running; quills or camouflage for defence
In or near water	Crocodile, frog	Streamlined body and webbed feet; moist skin in the frog

Why record this: "where does it live" is the criterion Aristotle used in the 4th century BCE. It is easy to observe, but you will see in section 12.5 exactly why it failed — a bat and an eagle both fly, yet a bat is a mammal that feeds its young on milk.

Q4.

Which animals in the picture seem active: (i) during the day? (ii) during the night? (iii) both during the day and the night?

Answer

When active	Animals in Fig. 12.2
(i) During the day (diurnal)	Peacock, eagle, spotted deer, langur, lion-tailed macaque, butterfly, dragonfly, small perching birds, sloth bear
(ii) During the night (nocturnal)	Owl, bats, slow loris, porcupine, civet, fireflies, python
(iii) Both day and night	Tiger, leopard, frog, crocodile — these appear on both halves of the picture and are active whenever prey is available

Why it happens: being night-active is not a habit, it is a set of structures. The owl has very large forward-facing eyes and asymmetrically placed ear openings, so it can locate a mouse by sound alone. Bats use echolocation. The slow loris has enormous eyes for low light. The firefly makes its own light to signal, which is only useful in the dark. Splitting the day this way also reduces competition — a night hunter and a day hunter can live in the same forest and rarely meet over the same prey.

Check it yourself: if you are unsure about an animal, write "unsure" in Table 12.1 rather than guessing. An honest blank is better data than an invented entry.

Q5.

Record your observations in Table 12.1.

Answer

Fill Table 12.1 with one row per organism. Here is a completed sample using animals from Fig. 12.2 (the book's own owl row is kept as the first line).

Organism	Where do you see it?	When does it appear to be active?	Any visible feature(s)
Owl	Tree	Night	Feathers
Eagle	Flying high in air	Day	Broad wings, hooked beak, sharp talons
Tiger	Forest floor	Day and night	Striped fur, padded paws, long canines
Spotted deer	Forest floor, near water	Day	Hooves, antlers, spotted coat
Bat	Flying high in air	Night	Wing membrane between fingers, large ears
Python	Tree branch	Night	Long limbless body, dry scales
Crocodile	Water	Day and night	Armoured skin, long snout, eyes on top of the head
Porcupine	Forest floor	Night	Long sharp quills
Butterfly	Flying near the ground	Day	Two pairs of scaly wings, jointed legs, coiled proboscis
Firefly	Flying near the ground	Night	Glowing abdomen, jointed legs

Tip: write the visible feature as a structure ("wing membrane", "quills", "hooves"), not as a behaviour ("flies", "runs"). Structures are what classification is built on; behaviour follows from them.

Q6.

Now, try grouping the same organisms in more than one way. Each time change the criterion you are using for grouping (Table 12.2).

Answer

Here are four different criteria applied to the same ten animals. Notice how the membership of the groups changes every time.

The grouping criterion	Which organisms fit in this group?	What feature or pattern helped you decide?
Carnivore	Eagle, tiger, leopard	Eating habits
Herbivore	Spotted deer, hare, langur, butterfly	Eating habits — grinding teeth, or a proboscis for nectar
Can fly	Eagle, owl, bat, butterfly, dragonfly, firefly	Presence of wings — but of three completely different kinds
Body covered with feathers	Eagle, owl, peacock	Body covering
Body covered with hair / fur	Tiger, leopard, deer, bat, langur, porcupine, civet, hare	Body covering; all also feed young on milk
Jointed legs and an exoskeleton	Butterfly, dragonfly, firefly	Internal and external structure (Arthropoda)
Nocturnal	Owl, bat, porcupine, civet, slow loris, firefly	Time of activity

Why it happens — and why it matters: the same organism lands in different groups depending on the criterion you choose. A bat is in "can fly" with the eagle, but in "has fur and feeds young on milk" with the tiger. Only one of those two groupings reflects how the animals are built and descended. This is exactly the problem that pushes the chapter forward: scientists must choose criteria that are fundamental — cell type, level of organisation, presence of a notochord — rather than criteria that are merely convenient, such as habitat or the ability to fly.

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