But the coral polyps still get eaten by butterflyfish , and parrotfish use their strong, beak-like fused teeth to grind up bits of coral tissue. The polyps may be of different colors, such as white, purple, orange, yellow, etc. At first sight when diving a coral reef, it looks like a garden. However, corals are not plants. Corals are colonies of thousand of tiny creatures that build upon another, all reaching out into the currents for food.
Corals have both sexual and asexual reproduction.
However, the time at which corals form gametes depends upon the size and age of the parent colony. Therefore, fragmentation or partial destruction can affect the fecundity of the colony. See the Birch Aquarium website for a video of the coral spawning . The bottom photograph is of yellow polyp black coral.