From conservation success stories in Pakistan's mountains to the true reason chameleons change colour — the wildlife facts, records, and ecosystem basics that show up everywhere in GK tests.
A single mountain valley in northern Pakistan can hold grass, insects, birds, wild goats, a rare cat and the soil bacteria that recycle them all. These living things, together with the water, rock and weather around them, form an ecosystem. This article explains how ecosystems work, how energy moves through them, why some species disappear and others recover, and how conservation status is measured, with a strong focus on the wildlife of Pakistan and South Asia.
What an ecosystem is · food chains, webs and energy · keystone species and relationships · biomes · biodiversity and threats · the IUCN Red List · conservation tools and success stories · wildlife of Pakistan · animal records · myths · four worked examples · key terms · practice questions and a quiz.
An ecosystem is a community of living things (biotic factors) interacting with their non-living surroundings (abiotic factors such as water, soil, sunlight, temperature and rock). Ecosystems can be as small as a pond or as large as a rainforest.
Ecologists describe life in levels, each one made of the one before it:
Two related ideas often get confused. A habitat is where an organism lives (its "address"). A niche is its role in the ecosystem (its "job"): what it eats, what eats it, and how it affects its surroundings.
Energy enters almost every ecosystem as sunlight. Producers (plants, algae and some bacteria) capture it through photosynthesis and turn it into food. Consumers get energy by eating: primary consumers are herbivores, secondary consumers eat the herbivores, and apex predators sit at the top, with no natural predators of their own. Decomposers (fungi and bacteria) break down dead material and return nutrients to the soil.
A food chain shows one path of energy, for example grass → markhor → snow leopard. In reality, most animals eat several foods, so the paths link into a food web.
Each step in a food chain is called a trophic level. At each step, most of the energy is used up for living (movement, keeping warm, growing) or lost as heat. As a rough rule, only about 10% of the energy passes to the next level. This is why food chains are short, why there are far fewer predators than prey, and why top predators need a large territory.
Question: A meadow's plants capture 10,000 kJ of energy. About how much reaches a snow leopard in the chain grass → markhor → snow leopard?
Step 1. Grass (producers) hold 10,000 kJ.
Step 2. The markhor (primary consumer) gets about 10%: 10,000 × 0.10 = 1,000 kJ.
Step 3. The snow leopard (secondary consumer) gets about 10% of that: 1,000 × 0.10 = 100 kJ.
Answer: About 100 kJ, only 1% of the original energy.
Question: What would happen in the web in Figure 1 if the snow leopard disappeared?
Step 1. Find what the snow leopard eats: markhor and ibex.
Step 2. With no predator, their populations may grow.
Step 3. More grazers eat more grass, so plants may be overgrazed, which can harm the soil and the other animals that depend on the plants.
Answer: The change spreads through the whole web. This is why every link matters.
A keystone species has a much bigger effect on its ecosystem than its numbers would suggest. Sea otters eat sea urchins, which protects kelp forests from being overgrazed. When wolves were reintroduced to Yellowstone National Park in the United States in the mid-1990s, scientists studied how they changed the behaviour of deer and the growth of plants along rivers, although the size of the effects is still debated.
Species also depend on each other in different ways, called symbiosis:
Competition (for food, water or space) and predation (one animal eating another) also shape who lives where.
| Biome | Key Feature | Example Location |
|---|---|---|
| Tropical rainforest | High rainfall all year; greatest biodiversity of any land biome | Amazon Basin |
| Savanna / grassland | Dominated by grasses with few trees; grazing animals | African savanna |
| Desert | Very low rainfall, extreme temperature swings | Sahara, Thar and Cholistan |
| Temperate forest | Distinct seasons; many trees lose their leaves | Eastern North America, Europe |
| Tundra | Frozen subsoil (permafrost), very short growing season | Arctic regions |
| Mountain (alpine) | Cold, windy, thin air; life changes with altitude | Karakoram, Himalaya, Hindu Kush |
| Ocean | Covers about 71% of Earth's surface | Pacific, Atlantic, Indian Oceans |
Pakistan packs a wide range of these into one country: high mountains in the north, the Indus river plains, deserts such as the Thar and Cholistan, and a coast. The Indus Delta's mangrove forests are among the largest arid-climate mangrove forests in the world and shelter fish, crabs and migratory birds.
Biodiversity is the variety of life: the number of species, the variety of genes within them and the variety of ecosystems. About two million species have been formally described, and scientists think many more are still unknown. In 2019 a major UN-backed assessment (IPBES) warned that up to a million species may be threatened with extinction, many within decades unless action is taken.
The main causes are easy to remember with the word HIPPO:
Extinction is natural over millions of years; the dinosaurs (other than birds) died out about 66 million years ago. But today's rate is far higher than the natural background rate. Well-known recent extinctions include the dodo (gone by the late 1600s), the passenger pigeon (the last one, Martha, died in 1914) and the thylacine or Tasmanian tiger (the last known one died in a zoo in 1936).
The IUCN Red List is the world's most widely used system for classifying how threatened a species is. It looks at population size, trends, range and other evidence. The main categories, from least to most concerning:
| Category | Meaning |
|---|---|
| Least Concern | Widespread and abundant |
| Near Threatened | Likely to become threatened soon |
| Vulnerable | High risk of extinction in the wild |
| Endangered | Very high risk of extinction in the wild |
| Critically Endangered | Extremely high risk of extinction in the wild |
| Extinct in the Wild | Survives only in captivity |
| Extinct | No individuals remain anywhere |
Two further labels exist: Data Deficient (not enough information) and Not Evaluated.
Statuses can move in either direction, and they change as new evidence is reviewed. Always check the IUCN Red List website for the latest assessment.
Species can improve as well as decline.
Community-based conservation, like the trophy hunting programmes that helped the markhor recover, shows that success often depends as much on giving local communities a direct financial stake in a species' survival as on the biology itself.
The tools of conservation include protected areas such as national parks and wildlife sanctuaries; laws that restrict hunting and trade; CITES, an international treaty (agreed in 1973) that regulates trade in endangered species; the Ramsar Convention (1971), which protects wetlands; captive breeding and reintroduction; and education. In Pakistan, protected areas include Khunjerab National Park (home to the Marco Polo sheep and snow leopard), Deosai National Park (a high plateau with Himalayan brown bears), Chitral Gol National Park (markhor) and Hingol National Park on the Balochistan coast, which is among the country's largest.
Tap any animal below for the full fact.
Tap an animal above to see its detail.
| Animal | Status (IUCN) | Found in |
|---|---|---|
| Markhor (national animal) | Near Threatened | Mountains of northern and western Pakistan |
| Snow leopard | Vulnerable | Gilgit-Baltistan, Chitral |
| Indus river dolphin | Endangered | Almost entirely in the Indus River, Pakistan (a small population lives in India) |
| Asiatic black bear | Vulnerable | Northern Pakistan and the Himalayan region |
| Marco Polo sheep (argali) | Near Threatened | High Pamir and Karakoram, including Khunjerab |
| Bengal tiger | Endangered | India and Bangladesh (Sundarbans) |
The Indus river dolphin is a special case. It has lost most of its eyesight over millions of years in the muddy waters of the Indus and finds its way almost entirely by echolocation. Only roughly two thousand are thought to survive, and a protected reserve exists on the Guddu–Sukkur stretch of the river in Sindh.
| Record | Animal |
|---|---|
| Largest animal ever known to exist | Blue whale (up to about 30 m long; heavier than any known dinosaur) |
| Fastest animal (in a hunting dive) | Peregrine falcon (over 300 km/h) |
| Fastest land animal | Cheetah (up to about 110 km/h in short bursts) |
| Tallest land animal | Giraffe (up to about 5.5 m) |
| Largest living land animal | African elephant |
| Longest migration | Arctic tern, which flies between the Arctic and Antarctic each year |
Question: How long does a cheetah (110 km/h) take to cover 1 km at top speed, compared with a peregrine falcon in a dive (300 km/h)?
Step 1. Time = distance ÷ speed. Cheetah: 1 ÷ 110 hours = 0.00909 hours.
Step 2. Convert to seconds: 0.00909 × 3,600 ≈ 33 seconds.
Step 3. Falcon: 1 ÷ 300 × 3,600 = 12 seconds.
Answer: About 33 seconds for the cheetah and 12 seconds for the falcon. (Real animals cannot keep top speed for long.)
The phrase "blind as a bat" has convinced most people this is literally true.
The fix: Bats are not blind. All bats can see, and many fruit bats have good eyesight and rely mostly on sight and smell. Many insect-eating bats use echolocation as an extra sense for hunting in the dark, but it does not replace their eyesight.
This is the most commonly assumed reason, but it is not the main one.
The fix: Chameleons mainly change colour to communicate, signalling mood, readiness to mate or aggression, and to help regulate body temperature. Most species are already fairly well camouflaged by their normal colour.
This is a very familiar claim.
The fix: A camel's hump stores fat, which is an energy reserve. Camels survive long periods without water for other reasons, such as the ability to tolerate a large loss of body water and to drink a great deal at once.
You may have heard this from adults and cartoons.
The fix: Experiments show that goldfish can learn and remember things, such as feeding times and simple tasks, for weeks or months.
The Indus river dolphin is functionally blind. Unlike bats, this one really does have almost no eyesight. It swims on its side and navigates through the muddy Indus mostly by echolocation.
Question: Match each description to a category: (a) "Common and widespread." (b) "Only survives in zoos." (c) "No individual remains anywhere." (d) "Very high risk of dying out in the wild."
Step 1. (a) describes a species with no major risk: Least Concern.
Step 2. (b) survives only in captivity: Extinct in the Wild.
Step 3. (c) none remain: Extinct. (d) very high risk in the wild: Endangered.
Answer: (a) Least Concern, (b) Extinct in the Wild, (c) Extinct, (d) Endangered.
| Term | Meaning |
|---|---|
| Ecosystem | Living things and their non-living surroundings working together |
| Habitat / niche | Where an organism lives / its role in the ecosystem |
| Producer / consumer / decomposer | Makes food from sunlight / eats other living things / breaks down dead matter |
| Trophic level | A feeding step in a food chain |
| Keystone species | A species with a very large effect on its ecosystem |
| Biodiversity | The variety of life in an area or on Earth |
| Endemic | Found naturally only in one place |
| Invasive species | A non-native species that spreads and harms native ones |
| Extinction | When no individuals of a species remain |
Try each question first, then tap it to reveal the answer.
A food chain shows one path of energy. A food web links many food chains together.
Only about 10% of energy passes to each next level, so less energy is available at the top.
It has a much larger effect on its ecosystem than its numbers suggest, for example sea otters protecting kelp forests.
Habitat loss, Invasive species, Pollution, Population growth (and climate change), Overharvesting.
The markhor, which moved from Endangered to Near Threatened.
Fat, not water.
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Suggested activities: have students draw a food web for a local habitat (a pond, a garden, a school field); hold a class "what if" game in which one species is removed and students predict the effects; and take a nature walk to count different species and talk about biodiversity. Conservation statuses are reviewed regularly by the IUCN, so please check the IUCN Red List website for the latest figures. This article is general education for students up to age 18.
10 questions. Select an answer for each, then submit to see your score instantly.