--- title: "Deep-sea life without sunlight" description: "Compare photosynthesis with chemosynthesis, which uses energy from chemical reactions to make food. Explain how vent bacteria support giant vent tube worms, clams and crabs. Distinguish food productio" canonical: https://lightmysky.com/learn/science/deep-sea-life-without-sunlight-mt_6Wx--Du8j3 source: https://lightmysky.com/learn/science/deep-sea-life-without-sunlight-mt_6Wx--Du8j3.md retrieved: 2026-10-19 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Deep-sea life without sunlight Compare photosynthesis with chemosynthesis, which uses energy from chemical reactions to make food. Explain how vent bacteria support giant vent tube worms, clams and crabs. Distinguish food production without light from independence from photosynthesis. Discuss vent-origin hypotheses and NASA research into possible life in icy moons' oceans. Subject: Science · Area: Ocean Life · Ages 11 to 13 Page: https://lightmysky.com/learn/science/deep-sea-life-without-sunlight-mt_6Wx--Du8j3 ## Ready when they can - Compare the energy sources used in photosynthesis and chemosynthesis - Explain how food-making vent bacteria support animals, including adult giant vent tube worms - Distinguish food production without light from independence from oxygen made by photosynthesis - Explain why scientists study vents when investigating life's origins and possible life on icy moons, without treating hypotheses as proof ## Lesson: Making food at deep-sea vents You have met deep-sea vents before. They release hot, chemical-rich water from cracks in the ocean floor. Sunlight does not reach these deep sites. Plants and algae use photosynthesis: light energy helps them make sugar from carbon dioxide and water. Some vent bacteria make food using chemical energy. Chemosynthesis makes food using energy from chemical reactions. Some vent bacteria react hydrogen sulphide with oxygen. The released energy lets them build sugars from carbon dioxide. These chemoautotrophic bacteria make their own food and can form the producer base of a food web. Sulphide supplies energy; carbon dioxide supplies carbon for food. *(drawing: Bacteria inside giant vent tube worms use chemical energy to make food that supports the worms.)* **Example.** Adult giant vent tube worms have no mouth or stomach. Bacteria inside them supply food. Some large clams at vents house bacteria in their gills. Some vent crabs eat bacterial mats or smaller animals. To predict a food-web change, follow who feeds on whom. If bacteria provide less food, animals depending on them may have less to eat. Predators of those animals may then have less prey. Other food sources can change this outcome. Making food without light does not make a whole vent community independent of photosynthesis. Vent animals and many vent bacteria need oxygen. Much of that oxygen was made by photosynthesis near the ocean surface and carried down by moving seawater. Food from surface waters can also reach the deep sea. *(drawing: Photosynthesis makes oxygen near the surface. Moving seawater can carry it to deep habitats.)* One hypothesis is that early life began near hydrothermal vents. Water, chemicals and reactions with rocks could have helped the first living systems form. This is not proved. Today's vent communities do not show where life began. Microbes use different chemical reactions, and some can live without oxygen. NASA researchers study Earth's vents to test ideas about life elsewhere. Europa orbits Jupiter, and Enceladus orbits Saturn. Evidence indicates oceans beneath their ice. Scientists ask whether water and chemical energy there could support life without sunlight reaching the oceans. Earth's vents do not prove that either moon has life or that both have active vents. **Recap.** Vent bacteria can make food using chemical energy. Many vent organisms still use oxygen made by photosynthesis. Vents help scientists investigate early life and possible life on icy moons. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Deep-Sea Creatures](https://lightmysky.com/learn/science/deep-sea-creatures-mt_dRCnJEIwk4) - [Photosynthesis](https://lightmysky.com/learn/science/photosynthesis-mt_zM5vu31jgl)