What is the difference between hard and soft corals?

Hard corals and soft corals represent two distinct groups within the coral family, primarily differentiated by their structural composition. Hard corals possess a rigid skeleton made of calcium carbonate, which gives them their characteristic solid form and contributes to the formation of coral reefs. This rigidity allows hard corals to create structured environments that can support a diverse range of marine life and withstand ocean currents.

In contrast, soft corals lack a solid skeletal structure and possess a more flexible body composition. They are supported by a network of tiny, soft, flexible polyps, allowing them to sway in the water. This flexibility enables soft corals to thrive in various environments, but they do not contribute to reef building in the same way that hard corals do.

While the other options touch on aspects of coral biology, they do not accurately represent the primary difference in structure between hard and soft corals. For example, not all hard corals are brightly colored, and soft corals can be equally vibrant. Growth rates vary among species but are not a definitive difference between the two categories. Additionally, depth tolerance can vary significantly among both hard and soft corals based on specific species and environmental conditions, rather than being an absolute characteristic of each group.