The coelom is the main body cavity in most animals and is positioned inside the body to surround and contain the digestive tract and other organs. In some animals, it is lined with mesothelium. In other animals, such as molluscs, it remains undifferentiated. In the past, and for practical purposes, coelom characteristics have been used to classify bilaterian animal phyla into informal groups.
Orthonectida is a small phylum of poorly known parasites of marine invertebrates that are among the simplest of multi-cellular organisms. Members of this phylum are known as orthonectids.
Acoelomorpha is a subphylum of very simple and small soft-bodied animals with planula-like features which live in marine or brackish waters. They usually live between grains of sediment, swimming as plankton, or crawling on other organisms, such as algae and corals. With the exception of two acoel freshwater species, all known Acoelomorphs are marine.
Acoela, or the acoels, is an order of small and simple invertebrates in the subphylum Acoelomorpha of phylum Xenacoelomorpha, a deep branching bilaterian group of animals, which resemble flatworms. Historically they were treated as an order of turbellarian flatworms.
Pseudocerotidae is a family of flatworms which includes the Bedford's flatworm. Pseudocerotidae are simple organisms categorized by their oval bodies and tentacles and bright colors. They use the cilia to glide along surfaces. Most commonly referred to as marine flatworms, closely related to the orders Macrostomorpha and Lecithoepitheliata. These organisms have very complex reproductive systems, no blood systems or organs for gas exchange, a simple brain and are hermaphroditic.
Pseudoceros is a genus of the flatworms Platyhelminthes.
Bispira brunnea, the social feather duster or cluster duster, is a species of marine bristleworm. They tend to live in groups of individuals, and are common off the Caribbean islands in southeast North America. The feather duster has one crown of various colors, however, the color of the crown seems to be consistent within individual colonies.
Yungia is a genus of flatworms.
Pseudoceros ferrugineus, the Fuchsia flatworm, is a marine flatworm species that belongs to the Pseudocerotidae family.
Thysanozoon nigropapillosum is a species of polyclad flatworms belonging to the family Pseudocerotidae. Some common names include gold-speckled flatworm, marine flatworm, yellow papillae flatworm, yellow-spotted flatworm, and yellow-spotted polyclad flatworm.
Cotylea is a suborder of free-living marine turbellarian flatworms in the order Polycladida.
Amakusaplana acroporae, the Acropora-eating flatworm or AEFW, is a species of free-living marine polyclad flatworms in the genus Amakusaplana.
Arnold Lang was a Swiss naturalist, a comparative anatomist and student of German biologist Ernst Haeckel.
Callioplana is a genus of flatworm polyclads belonging to the Callioplanidae family.
Diana Marcela Bolaños Rodríguez is a Colombian marine biologist who has studied and classified various types of platyhelminths. She was a recipient of the L'Oréal-UNESCO Fellowship for Women in Science in 2010, was selected as Colombian biologist of the year in 2012, and in 2013 was named by the BBC as one of the top ten women in science in Latin America.
Obama ladislavii is a species of Brazilian land planarian in the subfamily Geoplaninae. It is one of the most common land planarians in human-disturbed environments in southern Brazil and is easily identifiable by the green color of its dorsum.
Convolutriloba retrogemma is a reddish-brown flatworm 2 mm in length also commonly known as redbug, red planaria, rust flatworm, or simply red flatworm. It is a marine flatworm that gets energy from its endosymbiotic algae or from the consumption of small invertebrates such as copepods and rotifers. Like some other flatworms, it is known to starve coral of sunlight while searching for food on the corals' surface due to its rapid reproduction.
Pseudoceros canadensis, commonly known as the Puget flatworm, is a species of free-living flatworm in the genus Pseudoceros, belonging to the family Pseudocerotidae.
Parenchymia is a proposed clade encompassing Nemertea and Platyhelminthes. The clade was suggested in a 2019 study showing the clade as a sister to Annelida, with both groups together being sister to Lophophorata. The synapomorphies include similar organization of ciliary bands in the larva of both groups, as well as a lack of chitin, and is named for the abundant parenchyma found between the body wall and internal organs of both. A similar taxon, with Mollusca being likewise linked together with Symbion and Entoprocta, has been proposed in a clade called Tetraneuralia.
Pseudobiceros fulgor, also known the lightning worm, is a species of marine flatworm from the family Pseudocerotidae and belongs to the class Turbellaria. These flatworms are commonly found in the tropics of the Indo-Pacific region. They can be found in shallow coral reef environments.
