Echiura (Unsegmented Protostome Worms)


Echiurans are unsegmented protostome worms with setae and a proboscis that cannot be retracted into the body.

Keywords: worm; minor phylum; sexual dimorphism; infauna; phylogeny

Figure 1.

Bifurcate proboscis of two bonelliids.

Figure 2.

External view of a Thalassema sp.

Figure 3.

Internal view of an idealized echiuran worm.


Further Reading

Edmonds SJ (1982) Echiura. In: Parker SP (ed.) Synopsis and Classification of Living Organisms, vol. 2, pp. 65–66, pl. 92. New York: McGraw‐Hill Book Company.

Gruner H‐E (1982) Echiurida. In: Gruner H‐E (ed.) Lehrbuch der Speziellen Zoologie, 1: Wirbellose Tiere. 3. Teil: Mollusca, Sipunculida, Echiurida, Annelida, Onychophora, Tardigrada, Pentastomida, pp. 261–275. Jena, Germany: VEB Fischer Verlag.

Pilger JF (1993) Echiura. In: Harrison F‐W and Rice ME (eds) Microscopic Anatomy of Invertebrates, vol. 12: Onychophora, Chilopoda and Lesser Protostomata, pp. 185–236. New York: John Wiley and Sons.

Pilger JF (1997) Sipunculans and Echiurans. In: Gilbert SF and Raunio AM (eds) Embryology: Constructing the Organism, pp. 167–188. Sunderland, MA: Sinauer Associates.

Rice ME and Todorovic M (1975–76) Proceedings of the International Symposium on the Biology of the Sipuncula and Echiura. Belgrade, Yugoslavia: Naucno Delo.

Stephen AC and Edmonds SJ (1972) The Phyla Sipuncula and Echiura. London: Trustees of the British Museum (Natural History).

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How to Cite close
Saiz‐Salinas, José I(Apr 2001) Echiura (Unsegmented Protostome Worms). In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001601]