Diversification of acorn worms (Hemichordata, Enteropneusta) revealed in the deep sea

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 279; no. 1733; pp. 1646 - 1654
• Main Authors: Osborn, Karen J, Kuhnz, Linda A, Priede, Imants G, Urata, Makoto, Gebruk, Andrey V, Holland, Nicholas D
• Format: Journal Article
• Language: English
• Published: England Royal Society 22.04.2012; The Royal Society
• Subjects: ancestry; Animals; Aquatic Organisms - classification; Aquatic Organisms - genetics; Biological taxonomies; burrowing; Chordata; Deep Sea; Demersal; Eggs; Enteropneusta; Epibenthic; fruits; Hemichordata; image analysis; Invertebrates - classification; Invertebrates - genetics; Marine ecology; Materials; nucleotide sequences; Ocean floor; Pacific Ocean; Perceptual localization; Phylogenetics; Phylogeny; posture; proboscis; ribosomal DNA; Seas; skeleton; Species diversity; Torquaratoridae; Pacific Ocean
• ISSN: 0962-8452; 1471-2954; 1471-2945
• DOI: 10.1098/rspb.2011.1916

Enteropneusts (phylum Hemichordata), although studied extensively because of their close relationship to chordates, have long been considered shallow-water, burrowing animals. The present paper more than doubles the number of enteropneust species recorded in the deep sea based on high-resolution imaging and sampling with remotely operated vehicles. We provide direct evidence that some enteropneusts are highly mobile—using changes in posture and currents to drift between feeding sites—and are prominent members of deep, epibenthic communities. In addition, we provide ecological information for each species. We also show that despite their great morphological diversity, most deep-living enteropneusts form a single clade (the rediagnosed family Torquaratoridae) on the basis of rDNA sequences and morphology of the proboscis skeleton and stomochord. The phylogenetic position of the torquaratorids indicates that the group, after evolving from near-shore ancestors, radiated extensively in the deep sea.