There are a total of around 20,000 species of flatworms, some of which live in the sea, others in freshwater and some of which are parasitic. As the name suggests, flatworms are flat and relatively broad. They are primitive animals, but have a definite head and tail and a developed nervous system. The body and reproduction deviate so much from other worms that they have been categorized separately. The larger species glide through the water just like snails. Despite the fact that they are primitive, these animals are capable of learning. For example, they reacted to a lamp in experiments and can also learn to react to it always in the same way.

Members of the Phylum Platyhelminthes are typically called flatworms because of their flattened bodies. These animals lack appendages, and their bodies can take many forms, such as slender, leaflike, or ribbon-like. This diverse group of bilateral invertebrates ranges widely in size from 1mm or less to tapeworms that grow to many meters in length. There are both free-living and parasitic flatworms, and species are found in both freshwater and marine environments.

Platyhelminthes (fluke) is prey of:
Anatidae
Phalacrocoracidae

Based on studies in:
USA: New York, Long Island (Marine)

This list may not be complete but is based on published studies.

Platyhelminthes (fluke) preys on:
Plantae

Based on studies in:
USA: New York, Long Island (Marine)

This list may not be complete but is based on published studies.

Barcode of Life Data Systems (BOLD) Stats
                                        

Specimen Records:	8,196	Public Records:	2,299
Specimens with Sequences:	5,387	Public Species:	374
Specimens with Barcodes:	2,460	Public BINs:	240
Species:	613
Species With Barcodes:	396

Access Published & Released Data: Download FASTA File

Collection Sites: world map showing specimen collection locations for Platyhelminthes