Acoela
Acoela are a class of very small, free-living flatworms within the phylum Platyhelminthes. They are commonly known as acoel flatworms or acoel turbellarians, and they are found in marine environments worldwide. These worms are characterized by their simple body plan and lack of specialized organs, making them an interesting model for studying the evolution of bilaterian animals.
Characteristics
Acoel flatworms typically range in size from 0.5 to 10 millimeters in length. They have a simple, elongated body that is dorsoventrally flattened and lacks any internal cavities or specialized organs such as a gut, circulatory system, or respiratory system. Instead, they have a syncytial digestive system, where a network of cells is responsible for digestion. They also lack excretory and nervous systems as found in other flatworms. They are known to be hermaphroditic, with both male and female reproductive organs within the same individual.
Environments
Acoela are primarily found in marine environments, inhabiting a variety of habitats, including sandy beaches, rocky shores, coral reefs, and even deeper ocean floors. They are often found in association with seaweeds, sponges, and other benthic organisms. Some species are also known to be commensal or parasitic on other invertebrates.
References
For more information on Acoela, please refer to the following resources: