WCristatella mucedo is a bryozoan in the family Cristatellidae, and the only species of the genus Cristatella. They are noted for their elongated shape and colorless, transparent bodies.
WDiplozoon paradoxum is a flatworm (platyhelminth) from the class Monogenea. It is found in freshwater fishes in Asia and Europe and known for its complete monogamy. This parasite is commonly found on the gills of European cyprinid fishes. It is usually around 0.7 centimeters long and has bilateral symmetry. It has several hooks at its mouth which it uses to grab on to the gills of a fish. From there it feeds on the blood of a cyprinid.
WGyraulus piscinarum is a species of gastropods belonging to the family Planorbidae.
WHaemopis sanguisuga is a species of freshwater leech in the family Haemopidae. It is commonly called the horse-leech, but that is due to the similarity of its appearance to the leech Limnatis nilotica, which sometimes enters the nasal cavities of livestock. Haemopis sanguisuga does not behave in this way. Another synonym for this leech is Aulastomum gulo.
WOchridaspongia rotunda is freshwater sponge endemic to Lake Ohrid. This sponge is found mostly at depths of 30–50 m and water temperatures of 6–8 °C. Its circular shape indicates the animal lives under conditions of relatively calm water.
WPectinatella magnifica, the magnificent bryozoan, is a member of the Bryozoa phylum, in the order Plumatellida. It is a colony of organisms that bind together; these colonies can sometimes be 60 centimeters in diameter. These organisms can be found mostly in North America with some in Europe. They are often found attached to objects, but can be found free floating as well. They form a translucent body with many star-like blooms along the outside. The density of the organism is similar to that of gelatin, and is easily breakable into smaller chunks.
WPlumatella fungosa is a species of bryozoans from the family Plumatellidae.
WSpongilla lacustris is a species of freshwater sponge from the family Spongillidae. It inhabits freshwater rivers and lakes, often growing under logs or rocks. Lacustris is a Latin word meaning "related to or associated with lakes". The species ranges from North America to Europe and Asia. It is the most common freshwater sponge in central Europe. It is the most widespread sponge in Northern Britain, and is one of the most common species of sponges in lakes and canals. Spongilla lacustris have the ability to reproduce both sexually and asexually. They become dormant during winter. The growth form ranges from encrusting, to digitate, to branched, depending upon the quality of the habitat.
WSpongilla prespensis is freshwater sponge endemic to Lake Prespa. The sponge lives in rocky places in the lake.