---
title: "Biodiversity"
description: "Understand that biodiversity — the variety of different species in an ecosystem — is essential for healthy ecosystems, and that keystone species (like wolves in Yellowstone, sea otters in kelp forests"
canonical: https://lightmysky.com/learn/science/biodiversity-mt_NDZYiLvApW
source: https://lightmysky.com/learn/science/biodiversity-mt_NDZYiLvApW.md
retrieved: 2026-10-19
---

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# Biodiversity

Understand that biodiversity — the variety of different species in an ecosystem — is essential for healthy ecosystems, and that keystone species (like wolves in Yellowstone, sea otters in kelp forests, or bees as pollinators) have an outsized impact on their ecosystem, so that losing one key species can cause a cascade of changes affecting many others

Subject: Science · Area: Animals of the World · Ages 9 to 11
Page: https://lightmysky.com/learn/science/biodiversity-mt_NDZYiLvApW

## Ready when they can

- Defines biodiversity as the variety of species in an ecosystem
- Explains why biodiversity matters (stability, resilience, ecosystem services)
- Defines keystone species and gives at least 2 examples
- Describes a trophic cascade or chain reaction from removing/adding a species

## Lesson: Biodiversity and keystone species

Biodiversity means how many different kinds of living things share one place. A rainforest full of frogs, beetles, vines, and monkeys has high biodiversity. A parking lot has almost none.

Places with high biodiversity are more stable. If one kind of plant gets sick or a bad year hits, other species can still feed the animals and hold the ecosystem together. More kinds of life means more backup plans.

**Example.** Some species matter far more than their small numbers suggest. Scientists call these keystone species. Sea otters keep kelp forests healthy by eating sea urchins that would otherwise chew through the kelp. Bees keep gardens and farms going by carrying pollen from flower to flower so plants can make seeds.

*(drawing: One keystone species coming back changed the whole park, step by step.)*

**Tip.** Not every species has the same impact. Before worrying about saving one animal, it helps to ask: is this a keystone species? Losing one of those can set off a chain reaction through the whole ecosystem.

**Recap.** Biodiversity keeps ecosystems steady, and losing a single keystone species like a wolf, an otter, or a bee can change everything connected to it.

## Practice

24 questions on this page, each with its working shown.

## Needs first

- [Predator Hunting and Prey Defence Strategies](https://lightmysky.com/learn/science/predator-hunting-and-prey-defence-strategies-mt_Bztatrv-_v)
- [Three Kinds of Adaptations](https://lightmysky.com/learn/science/three-kinds-of-adaptations-mt_EaWjCyn8W2)
- [Symbiosis](https://lightmysky.com/learn/science/symbiosis-mt_H8OgKZbgGe)
- [The World of Minibeasts](https://lightmysky.com/learn/science/the-world-of-minibeasts-mt_R7LEuZjTmx)

## Opens up

- [Matter Cycling in Ecosystems](https://lightmysky.com/learn/science/matter-cycling-in-ecosystems-mt_0ajzcoKAKw)
- [The Biodiversity Crisis](https://lightmysky.com/learn/science/the-biodiversity-crisis-mt_44HkROUnzE)
- [Endangered & Extinct Species](https://lightmysky.com/learn/science/endangered-and-extinct-species-mt_5S4byWDX6n)
- [Protecting Endangered Animals](https://lightmysky.com/learn/science/protecting-endangered-animals-mt_pWwV_8OgXD)