Exploring the anatomy of Cossura pygodactylata Jones, 1956 (Annelida, Cossuridae) using micro-computed tomography, with special emphasis on gut architecture
- 44 Downloads
The anatomy of Cossura pygodactylata Jones, 1956 (Annelida; Cossuridae) is presented, based on the study of specimens collected during the BIOICE project in Icelandic waters and additional material from the White Sea. General gross external and internal anatomy were investigated by means of micro-computed tomography (micro-CT) and compared with results obtained with light microscopy histological sectioning (LMHS). Micro-CT revealed a highly regionalised gut, posterior to the pharyngeal cavity and oesophagus, divided in an anterior stomach and a posterior intestine with different morphologies. The stomach is in the thoracic region, dorsally positioned and divided in a short and narrow anterior part and a longer posterior one, with an increasing diameter towards its posterior end. Both stomach regions bear a dorsal infolding of tissue, along its inner wall, that resembles to the typhlosole of the Clitellata. The heart is dorsally located and contains a heart body above the hind stomach. The intestine is wider than the stomach, without dorsal infolding inside the lumen and filling most part of the internal body cavity. A transitional cup-shaped gut element connecting the stomach and the intestine could be observed at the level of the last thoracic segment. In general, the resolution of micro-CT images reflects reasonably well the main elements of gross external and internal anatomy of cossurids, and that of gut architecture in particular.
KeywordsNE Atlantic Ocean Micro-CT BIOICE Digestive system Polychaeta 3D anatomical reconstruction
The authors would like to thank Gudmundur Gudmundsson, Director of Collections and Systematics Department (Icelandic Institute of Natural History, Reykjavik), Gudmundur Vidir Helgason (Institute of Biology, University of Iceland, Reykjavik) and the Director of the Sandgerdi Marine Centre until 2013 for their help and advice during JP visits to the SMC, and to Solrun Bragadóttir and the rest of the women of the SMC involved in sorting the specimens from the BIOICE samples. The authors are also grateful to María Candás and Xela Cunha-Veira (EBMG, USC) for their help with the micro-CT images. The authors would also like to thank Nathalie Yonow (Swansea, Wales, UK) for linguistic correction of the manuscript, two anonymous reviewers for their helpful comments that greatly contributed to improve the organisation and clarity of the information provided and Karin Meiβner, Guest Editor of Marine Biodiversity, for her support during the review process and generous effort to improve the presentation of the text.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed by the authors.
All necessary permits for sampling and observational field studies have been obtained by the authors from the competent authorities and are mentioned in the acknowledgements, if applicable.
- Alba-Tercedor J, Sánchez-Tocino L (2011) The use of the SkyScan 1172 high-resolution micro-CT to elucidate if the spicules of the sea slugs (Mollusca: Nudibranchia, Opisthobranchia) have a structural or a defensive function. SkyScan Users Meeting 2011:113–121Google Scholar
- Day JH (1963) The Polychaete fauna of South Africa. Part 8: new species and records from grab samples and dredgings. Bull Br Mus Nat Hist, Ser Zool 10(7):383–445Google Scholar
- Faulwetter S, Dailianis T, Vasileiadou A, Arvanitidis C (2013a) Contrast enhancing techniques for the application of micro-CT in marine biodiversity studies. Microsc Anal 27:4–7Google Scholar
- Fournier JA, Petersen ME (1991) Cossura longocirrata: redescription and distribution, with notes on reproductive biology and a comparison of described species of Cossura (Polychaeta: Cossuridae). Ophelia Suppl 5:63–80Google Scholar
- Grube AE (1878) Annulata Semperiana. Beiträge zur Kenntniss der Annelidenfauna der Philippinen. Mem Acad Imp Sci St Petersb, Ser 7 25(8):1–300Google Scholar
- Jones ML (1956) Cossura pygodactylata, a new annelid from San Francisco Bay (Polychaeta: Cirratulidae). J Wash Acad Sci 46:127–130Google Scholar
- Michel C (1988) Intestine and digestive glands. In: Westheide W, Hermans CO (eds) The ultrastructure of Polychaeta. Microfauna Mar 4:157–176Google Scholar
- Parapar J, Kongsrud JA, Kongshavn K, Alvestad T, Aneiros F, Moreira J (2017b) A new species of Ampharete (Annelida: Ampharetidae) from the NW Iberian Peninsula, with a synoptic table comparing NE Atlantic species of the genus. Zool J Linn Soc. https://doi.org/10.1093/zoolinnean/zlx077 Google Scholar
- Parapar J, Moreira J, Helgason GV (2011) Distribution and diversity of the Opheliidae (Annelida, Polychaeta) on the continental shelf and slope of Iceland, with a review of the genus Ophelina in northeast Atlantic waters and description of two new species. Org Div Evol 11:83–105CrossRefGoogle Scholar
- Rouse GW (2001) Cossuridae day, 1963. In: Rouse GW, Pleijel F (eds) Polychaetes. Oxford University Press, Oxford, pp 46–48Google Scholar
- Saulnier-Michel C (1992) Chapter 2.3. Polychaeta: digestive system. In: Harrison FH, Gardiner SK (eds) Microscopic anatomy of invertebrates, vol. 7 Annelida, Wiley-Liss, New York, pp 53−69Google Scholar
- Tampi PRS (1958) Anatomy of Armandia leptocirris Grube (Polychaeta). J Zool Soc India 10:15–32Google Scholar
- Thulin G (1921) Biologisch-faunistiche Unterschungen aus dem Vresund. IV. Über Cossura longocirrata Webster & Benedict und über die Röhren von Disoma multisetosum Örsted. Lunds Univ Ersskr NF, Avd 2 17(10):2–15Google Scholar
- Tzetlin AB (1994) Fine morphology of the feeding apparatus of Cossura sp. (Polychaeta, Cossuridae) from the White Sea. Mém Mus Natl Hist Nat 162:137–143Google Scholar
- Webster HE, Benedict JE (1887) The Annelida Chaetopoda from Eastport, Maine. U.S. Commision of Fish and Fisheries. Rep US Fish Comm 1885:707–755Google Scholar
- Zhadan AE, Vortsepneva EV, Tzetlin AB (2012) Redescription and biology of Cossura pygodactylata Jones, 1956 (Polychaeta: Cossuridae) in the White Sea. Invertebr Zool 9:115–125Google Scholar