Which of the following triggered the large-scale growth of coral reefs millions of years ago? (1 point)
Responses
a. the relationship between corals and zooxanthellae
b.the effect of tsunamis on marine life
c.the evolution of new species of fishes
d.the extinction of some species of algae
a. the relationship between corals and zooxanthellae
The correct answer is:
a. the relationship between corals and zooxanthellae
The large-scale growth of coral reefs millions of years ago was primarily triggered by the symbiotic relationship between corals and zooxanthellae. The zooxanthellae are photosynthetic algae that live within the tissues of the coral and provide them with energy through photosynthesis. This mutualistic relationship allowed the corals to thrive in nutrient-poor tropical waters, leading to the formation of expansive coral reef ecosystems.
The correct answer is a. the relationship between corals and zooxanthellae.
To arrive at this answer, we need to understand the process of coral reef growth and the role of zooxanthellae.
Coral reefs are formed by the accumulation and growth of coral polyps, tiny organisms that secrete a hard external skeleton made of calcium carbonate. These polyps live in a symbiotic relationship with a type of photosynthetic algae called zooxanthellae.
Zooxanthellae live within the tissues of the coral polyps and provide them with nutrients through photosynthesis, while the coral polyps provide the algae with a safe habitat and access to sunlight. This relationship is vital for the growth and survival of coral reefs.
Millions of years ago, the evolution of this symbiotic relationship between corals and zooxanthellae triggered the large-scale growth of coral reefs. The algae's ability to photosynthesize and provide nutrients to corals allowed them to thrive in nutrient-poor tropical waters, leading to the formation of extensive reef ecosystems.
Therefore, the correct answer is a. the relationship between corals and zooxanthellae.