Nature · Level 3 · 149 words
Cities Beneath the Waves
Original passage © Team AM, written for Hone Literacy.
A coral reef looks like a colorful rocky garden, but it is actually built by living animals. Each coral is a colony of tiny soft-bodied creatures called polyps. Over many years, the polyps draw minerals from seawater to build hard limestone cups around themselves, and as old polyps die and new ones grow on top, the reef slowly rises. Inside the polyps live even smaller partners: microscopic algae that make food from sunlight and share it with the coral. In return, the algae get shelter. This partnership is why reefs grow only in clear, sunlit waters. When the water grows too warm, the coral expels its algae and turns pale, an event known as bleaching. Without its partners, the coral can starve. That is why scientists watch ocean temperatures so closely, since even a small, lasting rise can leave miles of reef pale and lifeless within a single season.
Comprehension questions
1. The passage is mainly about
- A how fish hunt on reefs
- B how living coral builds reefs and depends on algae
- C why oceans are getting warmer
- D how to dive safely
Show answer
B. how living coral builds reefs and depends on algae
The passage explains that reefs are built by coral polyps that partner with algae.
2. What do the algae give the coral in their partnership?
- A Shelter
- B Food made from sunlight
- C Limestone cups
- D Warm water
Show answer
B. Food made from sunlight
The text says the algae 'make food from sunlight and share it with the coral.'
3. Based on the passage, bleaching is harmful to coral because
- A it makes the coral too colorful
- B the coral loses the algae that feed it
- C it cools the water too much
- D it adds extra minerals
Show answer
B. the coral loses the algae that feed it
Bleaching is when coral expels its algae; without those partners 'the coral can starve.'
Source: Written for Hone Literacy. Original passage © Team AM, written for Hone Literacy.