Hemichordata (Acorn Worms)


The hemichordates are marine invertebrate organisms forming a phylum within the ‘Deuterostomia’; they comprise two classes, Pterobranchia and Enteropneusta.

Keywords: hemichordata; pterobranchia; enteropneusta; acorn worms; tomaria

Figure 1.

A diagrammatic drawing of the body plan of the hemichordata, (a) Pterobranchia, (b) Enteropneusta. Due to their considerable length, the stalk of the Pterobranchia and the metasoma of Enteropneusta have not been drawn in complete length. Numerous epidermal cells are of glandular nature as indicated by fine stippling.


Further Reading

Balser EJ and Ruppert EE (1990) Structure, ultrastructure, and function of the preoral heart‐kidney in Saccoglossus kowalewskii (Hemichordata, Enteropneusta) including new data on the stomochord. Acta Zoologica 71: 235–249.

Benito J and Pardos F (1997) Hemichordata. In: Harrison FW (ed.) Microscopic Anatomy of Invertebrates, vol. 15, pp. 15–101. New York: Wiley Liss.

Dilly PN, Welsch U and Rehkämper G (1986) On the fine structure of the alimentary tract of Cephalodiscus gracilis (Pterobranchia, Hemichordata). Acta Zoologica 67: 87–95.

Ruppert EE and Barnes RD (1994) Hemichordata. In: Invertebrate Zoology, 6th edn, pp. 865–877. Philadelphia, PA: Saunders.

Nielsen C (1995) Pterobranchia (chap. 47); Enteropneusta (chap. 50). In: Animal Evolution. Oxford: Oxford University Press.

Welsch U (1984) Hemichordata. In: Biology of the Integument, vol. 1, pp. 790–799. Heidelberg, Germany: Springer Verlag.

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How to Cite close
Welsch, Ulrich(Apr 2001) Hemichordata (Acorn Worms). In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0001617]