Surviving the Deep Sea
Lexile: 990 | Grade: 7
Passage
The deep sea is one of the most extreme environments on Earth. Sunlight cannot reach its cold, dark waters, and the pressure is so high it could crush a human submarine. Yet, life still exists there—thriving in total darkness.
Deep-sea creatures have adapted in unusual ways. Some fish produce their own light through a process called bioluminescence. This glow can help them attract prey or scare off predators.
Other animals, like giant tube worms, live near underwater volcanoes called hydrothermal vents. These vents release hot, mineral-rich water. Even though it’s boiling, some organisms use special bacteria to convert the chemicals into energy—a process called chemosynthesis.
Unlike plants on land that need sunlight to make food through photosynthesis, deep-sea creatures rely on chemistry instead.
Scientists continue to explore the deep sea using robotic submarines. Each discovery teaches us more about how life can survive—even in the most unlikely places.
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Questions
Q1: What is the main idea of the passage?
- A. Deep-sea creatures are dangerous to humans.
- B. The deep sea is an empty, lifeless place.
- C. Life in the deep sea has special adaptations that help it survive.
- D. Sunlight is the most important part of all ecosystems.
Q2: Why does the author describe hydrothermal vents and chemosynthesis?
- A. To explain how animals use sunlight in deep waters
- B. To show how organisms survive without sunlight
- C. To warn readers about underwater volcanoes
- D. To argue that vents are more important than plants
Q3: What does the word 'bioluminescence' most likely mean in paragraph 2?
- A. Movement through water
- B. Glowing in the dark
- C. Hiding from predators
- D. Floating without effort
Q4: What is the function of the sentence: 'Unlike plants on land that need sunlight to make food through photosynthesis, deep-sea creatures rely on chemistry instead.'?
- A. It introduces the idea that land and ocean creatures live in the same way.
- B. It compares how different environments use sunlight.
- C. It contrasts how energy is created in different ecosystems.
- D. It explains that sunlight is harmful to deep-sea life.
Q5: Why does the author include the detail about robotic submarines in the final paragraph?
- A. To explain how deep-sea creatures are hunted
- B. To show that humans can now live in the deep sea
- C. To suggest that deep-sea life is being harmed
- D. To highlight how scientists continue to learn from exploring deep-sea environments
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Answers & Reasoning
Q1: What is the main idea of the passage?
✅ Correct Answer: C
💡 Reasoning: The passage explains how life in the deep sea adapts to extreme conditions such as darkness, pressure, and heat.
Q2: Why does the author describe hydrothermal vents and chemosynthesis?
✅ Correct Answer: B
💡 Reasoning: The author explains chemosynthesis to show how some organisms can survive in complete darkness by using chemicals from vents.
Q3: What does the word 'bioluminescence' most likely mean in paragraph 2?
✅ Correct Answer: B
💡 Reasoning: The passage says fish produce their own light, so 'bioluminescence' must mean glowing in the dark.
Q4: What is the function of the sentence: 'Unlike plants on land that need sunlight to make food through photosynthesis, deep-sea creatures rely on chemistry instead.'?
✅ Correct Answer: C
💡 Reasoning: This sentence highlights the contrast between energy sources in two ecosystems—sunlight on land and chemicals in the deep sea.
Q5: Why does the author include the detail about robotic submarines in the final paragraph?
✅ Correct Answer: D
💡 Reasoning: The mention of robotic submarines emphasizes that scientific exploration is ongoing and reveals new information about deep-sea life.
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