Platyhelminthes (Flatworms)


The Platyhelminthes are a group of nonsegmented invertebrates that occur worldwide in a wide range of habitats; more than half of the species are parasitic.

Keywords: Platyhelminthes; flatworms; parasites; metazoans; invertebrates

Figure 1.

Examples of major platyhelminth taxa. (a) Dalyelliida. (b) Typhloplanida. (c) Kalyptorhynchia. (d) Proseriata. (e) Tricladida. (f) Polycladida. (g) Temnocephalida. (h) Monogenea. (i) Trematoda. (j) Cestoda. Redrawn and modified from various sources.

Figure 2.

Life cycle of the Chinese liver fluke.

Figure 3.

Phylogenetic tree of the Platyhelminthes using ‘total evidence’ (morphology, whole sequences of 18S rDNA). The numbers refer to morphological characters. From Littlewood et al. (1999a) with permission of Academic Press.


Further Reading

Balavoine G (1998) Are Platyhelminthes coelomates without a coelom? An argument based on the evolution of Hox genes. American Zoologist 38: 843–858.

Caira JN and Littlewood DTJ (in press) Diversity of Platyhelminthes. In: Levine S (ed.) Encyclopedia of Biodiversity. Boston, MA: Academic Press.

Cannon LRG (1986) Turbellaria of the World. A Guide to Families and Genera. Queensland, Australia: Qld. Museum, South Brisbane.

Ehlers U (1985) Das phylogenetische System der Plathelminthes. Stuttgart, Germany: Gustav Fischer Verlag.

Harrison FW and Bogitsh BJ (eds) (1991) Microscopic Anatomy of Invertebrates, vol. 3: Platyhelminthes and Nemertinea. New York: Wiley‐Liss.

Littlewood DTJ, Rohde K and Clough KA (1999a) The interrelationships of all major groups of Platyhelminthes – phylogenetic evidence from morphology and molecules. Biological Journal of the Linnean Society 66: 75–114.

Littlewood DTJ, Rohde K, Bray RA and Herniou EA (1999b) Phylogeny of the Platyhelminthes and the evolution of parasitism. Biological Journal of the Linnean Society 68: 257–287.

Rohde K (1994) The minor groups of parasitic Platyhelminthes. Advances in Parasitology 33: 145–234.

Rohde K (ed.) (1997) Origins of parasitism in the Platyhelminthes. International Journal for Parasitology 27: 677–746.

Ruiz‐Trillo I, Riutort M, Littlewood DTJ, Herniou EA and Baguña J (1999) Acoel flatworms: earliest extant bilaterian metazoans, not members of Platyhelminthes. Science 283: 1919–1923.

Schmidt GD and Roberts LS (1999) Foundations of Parasitology, 6th edn. Santiago, CA: McGraw‐Hill.

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How to Cite close
Rohde, Klaus(Apr 2001) Platyhelminthes (Flatworms). In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001585]