Macrostomum is a genus of Platyhelminthes with worldwide distribution, with over a hundred species described . These hermaphroditic, free-living flatworm

Flatworm

The flatworms, known in scientific literature as Platyhelminthes or Plathelminthes are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrate animals...

s are small in size, with large species reaching only about 5 mm (e.g. Macrostomum tuba). They are usually transparent, and the smaller species appear rather round than flat.

Name

The term "Macrostomum", meaning "big-mouthed", derives from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 μάκρος makros, "large", and στόμα, stoma, mouth. Relative to other turbellaria

Turbellaria

The Turbellaria are one of the traditional sub-divisions of the phylum Platyhelminthes , and include all the sub-groups that are not exclusively parasitic. There are about 4,500 species, which range from to in length...

, Macrostomum species have indeed a long mouth, connected to the gut by a muscular pharynx which can expand, in certain species, to almost the width of the animal.

Ecology

Macrostomum species inhabit different aquatic or moist environments. Marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 and brackish species are often interstitial (living in the space between grains of sediment), whereas freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 species are also frequently found associated with aquatic plants. Many of these small worms feed on unicellular algae

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 such as diatom

Diatom

Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...

s, others on zooplankton

Zooplankton

Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...

 or smaller benthic invertebrates.

Species

This genus includes Macrostomum lignano

Macrostomum lignano

Macrostomum lignano is a free-living, hermaphroditic flatworm. It is transparent and of small size , and is part of the intertidal sand meiofauna of the Adriatic Sea...

, a new model organism for studies on different areas of biology, including development, regeneration, stem cell biology, ageing, toxicology, genomics, and evolution

External links

• Turbellaria database
• www.macrostomum.net
• http://evolution.unibas.ch/scharer/research/current_research/macrostomum_overview.htmlEvolutionary Research on Macrostomum species at the University of Basel
  University of Basel
  The University of Basel is located in Basel, Switzerland, and is considered to be one of leading universities in the country...
  
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