Quentin Bone, Marine Biological Association of the United Kingdom, Plymouth, UK
Published online: April 2001
DOI: 10.1038/npg.els.0001616
Chaetognaths are elongate bilaterally symmetrical marine animals, ranging from 0.2 to 12 cm long. They have a distinct head bearing grasping spines, and a tail fin together with one or two paired fins. The bipartite body and head contain powerful rapidly contracting muscles, but apart from gut and gonads, internal organs are absent; there is no heart or blood system.
Keywords: chaetognath; arrow worm; predator; taxonomic isolation
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Figure 1. Scanning electron micrograph of head showing grasping hooks, mouth and teeth. The base of the grasping hooks is partially covered by the retractable prepuce.
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Figure 2. External appearance of Sagitta.
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Figure 3. Transverse section of a typical chaetognath showing internal anatomy.
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| Further Reading | |
| book Bone Q, Kapp H and Pierrot-Bults AC (eds) (1991) The Biology of Chaetognaths. Oxford: Oxford University Press. | |
| Shinn GL and Roberts ME (1994) Ultrastructure of hatching chaetognaths (Ferosagitta hispida): phylogenetic implications. Journal of Morphology 219: 143–163. | |
| Telford MJ and Holland PWH (1993) The phylogenetic affinities of the Chaetognaths: a molecular analysis. Molecular Biology and Evolution 10: 660–676. | |
| Telford MJ and Holland PWH (1997) Evolution of 28S ribosomal DNA in Chaetognaths: duplicate genes and molecular phylogeny. Journal of Molecular Evolution 44: 135–144. | |
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