十万个为什么·科学阅读30篇（2）
14 / 30
正在确认阅读权限…
How Do Coral Reefs Build Massive Structures Without Any Bones or Shells?
珊瑚礁如何在没有骨骼或外壳的情况下建造巨大结构？
-
Coral reefs are built by tiny animals called polyps that live in colonies underwater.
-
Each polyp secretes a hard external skeleton made of calcium carbonate from seawater minerals.
-
Over centuries, generations of polyps add layer upon layer, forming massive limestone frameworks.
-
Algae living inside coral tissues provide energy through photosynthesis, fueling this growth process.
-
Water temperature, light, and low nutrient levels must stay within narrow ranges for reefs to thrive.
-
When stressed by warming or pollution, corals expel their algae and bleach, halting construction.
-
Reef growth rates vary from 0.3 to 10 centimeters per year depending on species and conditions.
-
Some reefs, like Australia’s Great Barrier Reef, are over 20 million years old and span 2,300 kilometers.
-
Unlike shells or bones, coral skeletons are not part of the animal’s body but external deposits.
-
This collective, slow-building strategy makes reefs the largest biological structures visible from space.