Why are some plant and animal species extinct?

1. Habitat destruction: This is the leading cause of extinction. When natural habitats are destroyed or fragmented, plants and animals that depend on them can no longer survive. For example, the destruction of tropical rainforests has led to the extinction of many species of plants and animals, including the orangutan and the Sumatran tiger.

2. Overexploitation: Hunting, fishing, and other forms of overexploitation can drive a species to extinction. For example, the hunting of elephants for their ivory has led to a significant decline in their population, and they are now considered to be endangered.

3. Pollution: Pollution can poison air, water, and soil, making it impossible for plants and animals to survive. For example, water pollution from agricultural runoff can kill fish and other aquatic organisms, while air pollution from factories and vehicles can damage respiratory systems.

4. Climate change: Climate change is causing the Earth's temperature to rise, which can disrupt ecosystems and make it difficult for plants and animals to adapt. For example, rising sea levels are threatening coastal habitats and forcing some species to relocate or risk extinction.

5. Disease: Disease can also cause extinction. For example, the chestnut blight, a fungal disease that affects chestnut trees, has killed billions of chestnut trees in the United States, and it is now considered to be a threatened species.

6. Invasive species: Non-native species can outcompete native species for food and resources, and they can also transmit diseases. For example, the introduction of the cane toad to Australia has led to the decline of many native species, including the northern quoll.