Nielsen, C. & J.S. Ryland 1961. Three new species of Entoprocta from west Norway. ‑ Sarsia 1: 39‑45.

Nielsen, C. 1964. Studies on Danish Entoprocta. ‑ Ophelia 1: 1‑76.

Nielsen, C. 1964. Entoprocta from the Bergen area. ‑ Sarsia 17: 1‑6.

Nielsen, C. 1965. Pogonophora: Living species found off the coast of Florida. ‑  Science 150: 1475‑1476.

Nielsen, C. 1965. Four new species of Pogonophora from the Atlantic Ocean off  southern Florida. ‑ Bulletin of Marine Science 15: 964‑986.

Nielsen, C. 1966. On the life‑cycle of some Loxosomatidae (Entoprocta). ‑  Ophelia 3: 221‑247.

Nielsen, C. 1966. Some Loxosomatidae (Entoprocta) from the Atlantic coast of the United States. ‑ Ophelia 3: 249‑275.

Nielsen, C. 1967. Metamorphosis of the larva of Loxosomella murmanica (Nilus) (Entoprocta). ‑ Ophelia 4: 85‑89.

Nielsen, C. 1967. The larvae of Loxosomella pectinaricola and Loxosomella elegans (Entoprocta). ‑ Ophelia 4: 203‑206.

Nielsen, C. 1970. On metamorphosis and ancestrula formation in cyclostomatous bryozoans. ‑ Ophelia 7: 217‑256.

Nielsen, C. 1971. Entoproct life‑cycles and the entoproct/ectoproct relationship. ‑ Ophelia 9: 209‑341.

Nielsen, C. 1975. Observations on Buccinum undatum L. attacking bivalves and on prey responses, with a short review on attack methods of other prosobranchs. ‑ Ophelia 13: 87‑108.

Nielsen, C. & J. Rostgaard 1976. Structure and function of an entoproct tentacle with a discussion of ciliary feeding types. ‑ Ophelia 15: 115‑140.

Nielsen, C. 1976. Notes on boring bivalves from Phuket, Thailand. ‑ Ophelia 15: 141‑148.

Nielsen, C. 1976. An illustrated checklist of bivalves from PMBC beach with a reef flat at Phuket, Thailand. ‑ Research Bulletin, Phuket Marine Biological Center 9: 1‑25.

Nielsen, C. 1976. Notes on Littorina and Murex from the mangrove at Ao Nam‑Bor, Phuket, Thailand. ‑ Research Bulletin Phuket Marine Biological Center 11: 1‑4.

Nielsen, C. 1977. The relationships of Entoprocta, Ectoprocta and Phoronida. ‑ American Zoologist 17: 149‑150.

Nielsen, C., J.B. Kirkegaard & H. Lemche 1977. Pectinaria Lamarck, 1818 (Polychaeta), and the specific names P. belgica (Pallas, 1766) and P. koreni (Malmgren, 1866) to be validated under the plenary powers. Z.N.(S.) 2202. ‑ Bulletin of Zoological Nomenclature 34: 112‑122.

Nielsen, C. 1977. Phylogenetic considerations: The protostomian relationships. ‑ In R.M. Woollacott & R.L. Zimmer (eds): Biology of Bryozoans, pp 519‑534. Academic Press, New York.

Nielsen, C. & J.B. Kirkegaard 1978. Amended proposal for validating Pectinaria Lamarck, 1818 (Polychaeta), P. belgica (Pallas, 1766) and P. koreni (Malmgren, 1866) under the plenary powers. Z.N.(S.) 2202. ‑ Bulletin of Zoological Nomenclature 35: 25‑29.

Nielsen, C. & K.J. Pedersen 1979. Cystid structure and protrusion of the polypide in Crisia (Bryozoa, Cyclostomata). ‑ Acta Zoologica (Stockholm) 60: 65‑88.

Nielsen, C. 1979. Larval ciliary bands and metazoan phylogeny. ‑ Fortschritte in der zoolgischen Systematik und Evolutionsforschung 1: 178‑184.

Nielsen, C. 1980. On the occurrence of the prosobranchs Littorina neritoides, L. mariae and L. obtusata in Denmark. ‑ Journal of Molluscan Studies 46: 312‑316.

Ockelmann, K.W. & C. Nielsen 1981. On the biology of the prosobranch Lacuna parva in the Øresund. ‑ Ophelia 20: 1‑16.

Nielsen, C. 1981. On morphology and reproduction of 'Hippodiplosia' insculpta and Fenestrulina malusii (Bryozoa, Cheilostomata). ‑ Ophelia 20: 91‑125.

Nielsen, C. 1982. Entoprocta. ‑ In S.P. Parker (ed.): Synopsis and Classification of Living Organisms, vol. 2, pp 771‑772, pls 130‑131. McGraw‑Hill, New York.

Nielsen, C. 1984. Notes on a Zoanthina‑larva (Cnidaria) from Phuket, Thailand. ‑ Videnskabelige Meddelelser fra Dansk naturhistorisk Forening 145: 53‑60.

Nielsen, C. 1984. Yngelpleje hos mosdyr. ‑ Dyr i Natur og Museum 1: 16‑18. (F)

Nielsen, C. 1985. Animal phylogeny in the light of the trochaea theory. ‑ Biological Journal of the Linnean Society 25: 243‑299.

Nielsen, C. & A. Nørrevang 1985. The trochaea theory: an example of life cycle phylogeny. ‑ In S. Conway Morris, J.D. George, R. Gibson & H.M. Platts (eds): The Origin and Relationships of Lower Invertebrates, pp 28‑41. Oxford University Press, Oxford.

Nielsen, C. 1985. Ovicell formation in Tegella and four cellularioids (Bryozoa, Cheilostomata). ‑ In C. Nielsen & G.P. Larwood (eds): Bryozoa: Ordovician to Recent, pp 213‑220. Olsen & Olsen, Fredensborg.

Nielsen, C. 1985. Cilier fortæller om dyrenes slægtskabsforhold. ‑ Naturens Verden 1985: 312‑325. (F)

Nielsen, C. 1986. Fauna associated with the coral Porites from Phuket, Thailand. (Part 1): Bivalves with a description of a new species of Gastrochaena. ‑ Research Bulletin, Phuket Marine Biological Center 42: 1‑24.

Nielsen, C. 1987. Haeckelia (= Euchlora) and Hydroctena and the phylogenetic interrelationships of Cnidaria and Ctenophora. ‑ Zeitschrift für zoologische Systematik und Evolutionsforschung 25: 9‑12.

Nielsen, C. 1987. Structure and function of metazoan ciliary bands and their phylogenetic significance. ‑ Acta Zoologica (Stockholm) 68: 205‑262.

Nielsen, C. 1988. Ciliated larvae: A reply to O. M. Ivanova‑Kazas. ‑ Zoologichesky Zhurnal 67: 776‑777. (In Russian, English summary.)

Nielsen, C. 1988. Entoprocta + Brachiopoda. ‑ In R.H. Higgins & H. Thiel (eds): Introduction to the Study of Meiofauna, pp 444‑446. Smithsonian Institution Press, Washington, D.C.

Nielsen, C. 1989. Phylogeny and molecular data. ‑ Science 243: 548.

Nielsen, C. 1989. Entoprocts. ‑ Synopses of the British Fauna, N.S. 41: 1‑131.

Mackie, G.O., C. Nielsen & C.L. Singla 1989. The tentacle cilia of Aglantha digitale (Hydrozoa: Trachylina) and their control. ‑ Acta Zoologica (Stockholm) 70: 132‑141.

McLean, N. & C. Nielsen 1989. Oodinium jordani n. sp., a dinoflagellate (Dinoflagellata: Oodiniidae) ectoparasitic on Sagitta elegans (Chaetognatha). ‑ Diseases of Aquatic Organisms 7: 61‑66.

Nielsen, C. 1990. Nyt om udviklingen hos armfødder (brachiopoder). ‑ Dyr i Natur og Museum 1990: 22‑23. (F)

Nielsen, C. 1990. Bryozoa Ectoprocta + Bryozoa Entoprocta. ‑ In K.G. Adiyodi & R.G. Adiyodi (eds): Reproductive Biology of Invertebrates, vol. 4B, pp 185‑209. Oxford & IBH Publishing Co., New Delhi.

Nielsen, C. 1991. The development of the brachiopod Crania (Neocrania) anomala (O.F. Müller) and its phylogenetic significance. ‑ Acta Zoologica (Stockholm) 72: 1‑22.

Nielsen, C. 1991. A revision of the genus Loxosoma (Entoprocta) with description of three new species from Phuket, Thailand (Abstract). - Bulletin de la Société des Sciences naturelles de l'Ouest de la France, Mémoire Hors Séries 1: 575 (F.P. Bigey (ed.): Bryozoaires actuels et fossiles: Bryozoa living and fossil, Nantes).

Nielsen, C. 1991. The origin of the Metazoa. - In E.C. Dudley (ed.): The Unity of Evolutionary Biology, pp 445-446. Dioscorides Press, Portland. Oregon.

Nielsen, C. 1994. Larval and adult characters in animal phylogeny. - American Zoologist 34: 492-501.

Nielsen, C. 1994. Bryozoa Entoprocta. - In K.G. Adiyodi & R.G. Adiyodi (eds): Reproductive Biology of Invertebrates, vol. VI, B, pp. 309-314. John Wiley & Sons, Chichester.

Nielsen, C., N. Scharff & D. Eibye-Jacobsen 1996. Cladistic analyses of the Animal Kingdom. - Biological Journal of the Linnean Society 57: 385-410.

Nielsen, C. 1996. Three new species of Loxosoma (Entoprocta) from Phuket, Thailand with a review of the genus. - Zoologica Scripta 25: 61-75.

Eibye-Jacobsen, D. & C. Nielsen 1996 [1997]. The rearticulation of annelids. - Zoologica Scripta 25: 275-282.

Tendal, O. S. & C. Nielsen. 1997. Bægerkorallen (Caryophyllia smithii) - ny koral for Danmark. - Flora og Fauna 103: 7-9.

Nielsen, C. & Å. Jespersen 1997. Entoprocta. - In F. W. Harrison (ed.): Microscopic Anatomy of Invertebrates, vol. 13, pp. 13-43. Wiley-Liss, New York.

Nielsen, C. 1997. Tail evolution. - Science 277: 1422.

Nielsen, C. 1997. Animal classification - then and now. - Bulletin de la Société Zoologique de France 122: 243-253

Nielsen, C. 1997. The phylogenetic position of the Arthropoda. - In R. A. Fortey & R. H. Thomas (eds): Arthropod Relationships, pp. 11-22 (Systematics Association Special Volume Series, 55). Chapman & Hall, London

Nielsen, C. 1998. News and views: Sequences lead to trees of worms. - Nature 392: 25-26

Nielsen, C. 1998. Origin and evolution of animal life cycles. - Biological Reviews 73: 125-155

Nielsen, C. & H. U. Riisgård 1998. Tentacle structure and filter-feeding in Crisia eburnea and other cyclostomatous bryozoans, with a review of upstream-collecting mechanisms. - Marine Ecology Progress Series 168: 163-186

Nielsen, C. 1998. Morphological approaches to phylogeny. - American Zoologist 38: 942-952

Nielsen, C. 1999. Origin of the chordate central nervous system - and the origin of the chordates. - Development Genes and Evolution 209: 198-205

Nielsen, C. 1999. Nyt om hvirveldyrenes oprindelse - vender vi ryggen fremad? - Naturens Verden 12(6): 33-40.

Nielsen, C. 2000. The phylogenetic position of Entoprocta and Ectoprocta. - In A. Herrera Cubilla & J.B.C. Jackson (eds): Proceedings of the 11th International Bryozoology Association Conference, pp 66-73. Smithsonian Tropical Research Institute, Balboa, Panama.

Nielsen, C. 2000. The origin of metamorphosis. - Evolution & Development 2: 127-129.

Riisgård, H.U., C. Nielsen & P.S. Larsen 2000. Downstream collecting in ciliary suspension feeders: the catch-up principle. - Marine Ecology Progress Series 207: 33-51.

Nielsen, C. 2000. Review of: Zoological Catalogue of Australia, vol. 34: Hemichordata, Tunicata, Cephalochordata. - Quarterly Review of Biology 75: 465.

Nielsen, C. 2001. Animal Evolution: Interrelationships of the Living Phyla, 2nd edition, 563 pp. Oxford Univ. Press, Oxford.
     Reviews:
          Contributions to Zoology 70: 181-184 (2001, R. Jenner)
          Ethology, Ecology & Evolution 13: 308 (2001)
          Palaeontological Association Newsletter 49: 78-80 (2002, G. Budd)

Nielsen, C. 1994-2001. Entries for Danmarks Nationalleksikon (Den store danske Encyclopædi). Gyldendal, Copenhagen.

Biologisk klassifikation [biological classification] (3: 29-30). Chordater (4: 176). Dicyemida (5: 122). Dyr [animals] (5: 311-312). Endostyl (5: 538). Enteropneuster (5: 571). Entoprocter (5: 571-572). Grobben, Karl (7: 585). Hatschek, Berthold (8: 272). Havdyresamfund [marine animal communities] (8: 289-291). Hyman, Libbie Henrietta (9: 135-136). Kaestner, Alfred (10: 243). Nomenklatur, dyr [nomenclature, animals] (14: 225). Orthonectida (14: 553). Phoronida (15: 219). Pilorme [chaetognaths] (15: 240). Placozoer (15: 263). Pogonoforer (15: 317). Pterobranchia (15: 535). Remane, Alfred (16: 104). Spiralia (17: 599). Thorson, Gunnar (19: 67). Zoologi (20: 471-473).

Nielsen, C. 2002. Entoprocta. - In C.M. Young, M.A. Sewell & M.E. Rice (eds): Atlas of Marine Invertebrate Larvae, pp. 397-409. Academic Press, London.

Nielsen, C. 2002. Bryozoa (Ectoprocta: ‘Moss’ Animals). - In A. O’Daly (ed.): Encyclopedia of Life Sciences, vol. 3, pp. 475-479. Macmillan Reference, London (electronic version:

Nielsen, C. 2002. Entoprocta. - In A. O’Daly (ed.): Encyclopedia of Life Sciences, vol. 6, pp. 345-346. Macmillan Reference, London. (electronic version:

Riisgård, H.U., A. Grémare, J.M. Amouroux, F. Charles, G. Vétion, R. Rosenberg & C. Nielsen 2002. A comparative study of water processing in two filter-feeding polychaetes (Ditrupa arietina and Euchone papillosa) from two different habitats. - Marine Ecology Progress Series 229: 113-126.

Nielsen, C. 2002. Protostomia and Deuterostomia. - In M. Pagel (ed.): Encyclopedia of Evolution, vol. 2, pp 961-963. Oxford Univ. Press, New York.

Riisgård, H.U., P.S. Larsen & C. Nielsen 2002. Filtrerende bryozoer, partikler og strømmende vand. Naturens Verden 2002 (5): 12-23.

Nielsen, C. 2002. Ciliary filter-feeding structures in adult and larval gymnolaemate bryozoans. - Invertebrate Biology 121: 255-261.

Shunatova, N.N. & C. Nielsen 2002. Putative sensory structures in marine bryozoans. - Invertebrate Biology 121: 262-270.

Nielsen, C. 2002. The phylogenetic position of Entoprocta, Ectoprocta, Phoronida and Brachiopoda. - Integrative and Comparative Biology 42: 685-691.

Nielsen, C. & R. Meier 2002. What cell lineages tell us about the evolution of Spiralia remains to be seen. - Evolution 56: 2554-2557.

Nielsen, C. & P. Martinez 2003. Patterns of gene expression: homology or homocracy? - Development, Genes and Evolution 213: 149-154.

Knudsen, J., K.R. Jensen, C. Nielsen & R.I. Johnson 2003. Lorentz Spengler’s descriptions of freshwater mussels (Mollusca: Unionacea): translation and notes. - Steenstrupia 27: 263-279.

Nielsen, C. 2003. Defining phyla: morphological and molecular clues to metazoan evolution. - Evolution & Development 5: 386-393.

Nielsen, C. 2003. Proposing a solution to the Articulata-Ecdysozoa controversy? - Zoologica Scripta 32: 475-482.

Bourlat, S.J., C. Nielsen, A.E. Lockyer, D.T. Littlewood & M.J. Telford 2003. Xenoturbella is a deuterostome that eats molluscs. - Nature 424: 925-928 (plus supplementary information).

Nielsen, C. 2004. Trochophora larvae: cell-lineages, ciliary bands and body regions. 1. Annelida and Mollusca. - Journal of Experimental Zoology (Molecular and Developmental  Evolution) 302B: 35-68.  

Nielsen, C. 2004. To sære “orme”. - Dyr i Natur og Museum 2004(1): 27-29.

Jespersen, Å., J. Lützen & C. Nielsen 2004. On three species and two new genera (Montacutella and Brachiomya) of galeommatoid bivalves from the irregular sea urchin Brissus latecarinatus with emphasis on their reproduction. - Zoologischer Anzeiger 243: 3-19. 

Vinther, J. & C. Nielsen 2005. The Early Cambrian Halkieria is a mollusc. - Zoologica Scripta 34: 81-89. 

Nielsen, C. 2005. Trochophora larvae and adult body regions in annelids: some conclusions. – Hydrobiologia 535/536: 23-24.

Lützen, J. & C. Nielsen 2005. Galeommatid bivalves from Phuket, Thailand. - Zoological Journal of the Linnean Society 144: 261-308.

Nielsen, C. 2005. Larval and adult brains. - Evolution & Development 7: 483-489.

Nielsen, C. 2005. Trochophora larvae: cell-lineages, ciliary bands and body regions. 2. Other groups and general discussion. - Journal of Experimental Zoology (Molecular and Developmental  Evolution) 304B: 401-447.