Which group of fish are sex-changing farmers?

Coral reefs are incredibly complicated ecosystems. Even though coral reefs take up less than 1% of the ocean, and yet they contain over a quarter of life in the ocean! They are so many species living in coral reefs that they have earned the name “rainforests of the sea.”

One important component of many coral reefs is seaweed, which usually grows between the shore and the reef. Some people feared seaweed was taking over coral reefs, but when the seaweed was removed, they found that the coral began to die at a much faster rate. Scientists eventually figured out that the seaweed was actually protecting the coral by shading it from the sun and stopping harmful water and runoff from the shore from reaching the coral.

Serranids are a group of brightly coloured reef fish who are all born female. They live in groups with a dominant male and female, and when the male dies or disappears, the dominant female begins to change into a male. If the male reappears within ten days, she’ll change back, but if more than ten days pass, she remains male for the rest of her life.

Serranids are actually the farmers of the reef. They cultivate seaweed and help keep it healthy by removing sea urchins that are feeding on the seaweed, as well as removing inedible kinds of seaweed so that more edible kinds can grow. iif you watch a reef in action for a while, you might see that it isn’t just scientists who understand the importance of seaweed – the serranid fish do, too!