Acoel flatworms can reach plague proportions in the home aquarium. The photos shows Waminoa flatworms on a bubble coral.
The acoel flatworms are some of the most primitive animals on the planet. They actually lack a body cavity and a gut. Most of the flatworms we encounter in the aquarium trade are innocuous, causing no harm to corals. The acoels that are most often encountered living on mushroom anemones, soft corals and large-polyped stony corals are reported to graze on minute crustaceans, algae and detritus that adheres to the mucus of these cnidarians. When in small numbers, they do not appear to harm their host, but severe infestations can interfere with the photosynthetic activity of the zooxanthellae-hosting corals they infest.
