Marine Flatworm

Pseudobiceros hancockanus is one of the most flamboyant marine flatworms found in Komodo's waters, featuring a velvety black body bordered with a striking neon blue-purple margin and a bright orange or yellow sub-marginal band. At first glance, many divers mistake this animal for a nudibranch, but flatworms are an entirely different phylum — they are platyhelminthes rather than molluscs, with much simpler body plans and no gills or rhinophores. Marine flatworms glide across the reef surface using microscopic cilia on their underside, propelled by a layer of mucous, moving with a fluid, almost ethereal grace. In Komodo, colourful flatworms are found at most dive sites, often on sponge-encrusted reef walls or under coral rubble. They are carnivorous, feeding on colonial tunicates, bryozoans, and other sessile invertebrates. Their bold colouration serves the same purpose as in nudibranchs — warning predators that they taste terrible. Some flatworms can even swim by undulating their thin, flexible bodies through the water when dislodged from the substrate.