Midnight Vents Reading Worksheet
Science & Nature Informational Reading
Lexile Band: 530L–680L (610L)
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Midnight Vents: Life in the Deep Ocean
How an amazing discovery at the bottom of the sea surprised scientists around the world.
In 1977, a group of scientists went on a big adventure. They climbed inside a small submarine named Alvin. They dived deep down into the Pacific Ocean. The submarine went down nearly 8,000 feet! At the bottom, the water was freezing cold. The ocean floor was pitch black because sunlight cannot reach that deep.
Scientists thought the deep ocean was an empty desert where nothing could live. But when they turned on their bright lights, they saw something amazing. Tall rock towers stood on the seafloor. Black, boiling-hot water shot out of the tops!
These rock chimneys are called hydrothermal vents. They form when cold ocean water seeps into cracks in the Earth's crust. Hot underground rocks heat the water until it is boiling hot. Then, the water shoots back up into the cold sea. The minerals in the water turn hard and build tall chimneys called "black smokers."
Even more surprising, thousands of strange creatures lived around the vents. On land, plants need sunlight to make food. This is called photosynthesis. But in the deep ocean, the sun never shines. How could these animals stay alive without sunlight?
The answer is a process called chemosynthesis. Instead of using sunlight, tiny living things called bacteria use chemicals from the hot vent water. They make food out of a smelly gas called hydrogen sulfide. These bacteria feed all the other animals in the vent community.
Many strange animals crowd around the warm vents. The most famous are giant tube worms. They can grow eight feet tall! These giant worms have no eyes, no mouth, and no stomach. Instead, billions of helpful bacteria live safely inside each worm. The bacteria make food for the worm, and the worm gives the bacteria a safe home. When two living things help each other survive, it is called symbiosis.
Other animals live here too. Hairy yeti crabs grow bacteria on their claws to eat. Ghost-white shrimp crawl on the rocks. Pale fish swim through the warm water.
However, living near a vent is risky. An earthquake can suddenly stop the flow of hot water. If the vent stops, the animals can freeze and starve. To survive, adult animals release millions of tiny babies, called larvae. The babies drift through ocean currents, looking for a new hot vent to call home.
Words to Know
Hydrothermal Vent: A rock chimney on the seafloor that shoots out hot water.
Chemosynthesis: Making food from chemicals instead of sunlight.
Symbiosis: A helpful partnership where two living things help each other.
Larvae: Tiny baby animals before they grow into adults.
Did You Know?
Vent water gets super hot (over 700°F), but heavy ocean water pressing down keeps it from boiling into steam!
Read the story and words above before answering the questions on Page 2. Page 1 of 2
Midnight Vents • Reading Questions
Read each question carefully. Use clues and details from the story to answer.
Total: 25 Points
Part 1: Main Idea & Details Skill: Main Idea
1. What is the main idea of the whole reading passage?
A. Submarines like Alvin can dive into the ocean to explore shipwrecks.
B. Hydrothermal vents prove that amazing animal communities can live without sunlight.
C. Giant tube worms are the only animals that can survive in freezing ocean water.
D. Sunlight reaches every corner of the ocean from the top to the bottom.
2. What is the main idea of the paragraph about chemosynthesis?
A. Tiny bacteria use chemicals from the hot water to make food for other creatures.
B. Plants grow on the seafloor by catching light from volcanic rocks.
C. Chemicals in the ocean make it impossible for any bacteria to grow.
D. Submarines use battery power to turn seawater into fresh water.
Part 2: Clues & Inferences Skill: Inferences & Evidence
3. Giant tube worms have no mouth and no stomach. Based on the text, how do they get food to stay alive?
A. They swim up to the surface every day to catch tiny plants.
B. Helpful bacteria living inside their bodies make food for them.
C. They eat sand and rocks from the bottom of the sea.
D. They sleep through the cold winter without needing any food.
4. Which sentence from the story shows that life near a vent can be dangerous?
A. "In 1977, a group of scientists went on a big adventure."
B. "Hot underground rocks heat the water until it is boiling hot."
C. "If the vent stops, the animals can freeze and starve."
D. "Ghost-white shrimp crawl on the rocks."
Part 3: Short Written Responses Skill: Written Details
5. Compare: How is getting food in the deep ocean different from how plants get food on land? Use details from the text.
6. Explain: Why is living near a hydrothermal vent both a great home and a dangerous home? Use clues from the story.
Midnight Vents • Informational Reading Worksheet (Lexile 530L–680L) Page 2 of 2
Midnight Vents Answer Key
Teacher Resource Answer Key & Scoring Guide
Total Score: 25 Points
Midnight Vents: Answer Key & Guide
Science Informational Text • Reading Level: Lexile Band 530L–680L (Midpoint 610L)
Quick Key: 1: B 2: A 3: B 4: C
Parts 1 & 2: Multiple Choice Rationales (4 Points Each • 16 Points Total) Skills: Main Idea & Text Evidence
1. Main Idea of Passage Correct: B
Rationale: The story focuses on how hydrothermal vents prove that crowded animal communities can survive in pitch darkness without sunlight.
Distractor Notes: (A) discusses shipwrecks; (C) is factually incorrect; (D) falsely claims sunlight reaches deep water.
2. Chemosynthesis Paragraph Correct: A
Rationale: The paragraph explains how bacteria make food from hot vent chemicals, forming the base food source for all the other animals.
Distractor Notes: (B) is false (no plants); (C) contradicts bacteria survival; (D) describes batteries.
3. Inference: Tube Worm Food Correct: B
Rationale: Without mouths or stomachs, students infer that the symbiotic bacteria inside their bodies produce all the nourishment the worms need.
Distractor Notes: (A) contradicts ocean depth; (C) is untrue; (D) misinterprets seasonal biology.
4. Evidence: Vent Danger Correct: C
Rationale: Option C directly quotes the sentence explaining that if the hot water stops, the animals can freeze and starve.
Distractor Notes: (A), (B), and (D) are true details from the text, but do not show danger or risk.
Part 3: Written Response Rubrics & Exemplars (9 Points Total) Skill: Writing with Text Evidence
Question 5: Comparing Food Sources (4 Points) Full Credit: 4 pts • Partial: 2 pts • Minimal: 1 pt
Exemplar Student Response:
"On land, plants need sunlight to make food through photosynthesis. In the deep ocean, there is no sunlight. Instead, tiny bacteria use chemicals from the hot vent water to make food through chemosynthesis."
• 2 Points: Contrasts land plants (sunlight/photosynthesis) with vents (chemicals/chemosynthesis).
• 2 Points: Uses specific clues from the reading (bacteria, dark ocean, chemicals).
Question 6: Great Home vs. Dangerous Home (5 Points) Full Credit: 5 pts • Partial: 3 pts • Minimal: 1 pt
Exemplar Student Response:
"Living by a vent is a great home because the hot water gives bacteria the chemicals they need to make food, so giant worms and crabs have plenty to eat and stay warm. But it is dangerous because earthquakes can shut off the hot water, and the animals can freeze and starve."
