How does the transfer of energy throughout an ecosystem begin?

99.99% of living things on Earth get all of their energy from the sun. Plants start the food web, getting their energy directly from the sun through photosynthesis. Any animals that eat the plants take that energy, and animals that eat those animals get their energy thirdhand, and so on. Energy can travel this way from the sun to even the deep sea, where scavengers devour whatever dies and falls from the sunlit surface.

Interestingly, in the deepest parts of the oceans, energy can come from another source - the Earth's mantle. Hydrothermal vents, or "black smokers", are vents that spew superheated water heated by the magma below the crust. Various types of bacteria have evolved to survive on the nutrient-rich water, and these are in turn eaten by giant tube worms, yeti crabs, and clams. Those in turn are eaten by the deepest scavenger fish and a few species of octopi.

The transfer of energy throughout an ecosystem begins with producers, such as plants, using sunlight to convert carbon dioxide and water into glucose through photosynthesis.