Fun Flatworm Facts

Marine flatworms are invertebrates that usually are vibrantly colored. Most species of flatworms are more active at night and can be found around rocky substrates, fouling communities, or maybe even swimming around the IOP Marina!

Tiger flatworm (Prostheceraeus crozieri) found at the IOP Marina!

Some flatworms contain poison called tetrodotoxin. This toxin or poison is also found in certain species of frog, the blue ringed octopus, and puffers! Not all flatworms are poisonous but some have specially adapted to look like toxic nudibranchs for protection. 

Different species of marine flatworm play different roles for the environment. The Tiger flatworm preys mostly on orange tunicates. Other marine flatworms are similar in that their role is to feed on the bryozoans (mossy animals) and tunicates. There are even some marine flatworms used as indicator species in estuaries. One article says, “their absence or abundance in an ecosystem provide scientists with important insights about the biological, chemical and physical processes taking place in and around the marsh”.