title: Understanding irregular shell formation of Nautilus in aquaria: chemical composition and structural analysis.
abstract: Irregular shell formation and black lines on the outside of live chambered nautilus shells have been observed in all adult specimens at aquariums and zoos soon after the organisms enter aquaria. Black lines have also been observed in wild animals at sites of broken shell, but continued growth from that point returns to a normal, smooth structure. In contrast, rough irregular deposition of shell continues throughout residence in aquaria. The composition and reasons for deposition of the black material and mitigation of this irregular shell formation is the subject of the current study. A variety of analytical techniques were used, including stable isotope mass spectrometry (SI-MS), inductively coupled plasma mass spectrometry (ICP-MS), micro x-ray fluorescence (µXRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM) based X-ray microanalysis. Results indicate that the black material contains excess amounts of copper, zinc, and bromine which are unrelated to the Nautilus diet. The combination of these elements and proteins plays an important role in shell formation, growth, and strengthening. Further study will be needed to compare the proteomics of the shell under aquaria versus natural wild environments. The question remains as to whether the occurrence of the black lines indicates normal healing followed by growth irregularities that are caused by stress from chemical or environmental conditions. In this paper we begin to address this question by examining elemental and isotopic differences of Nautilus diet and salt water. The atomic composition and light stable isotopic ratios of the Nautilus shell formed in aquaria verses wild conditions are presented.
authors.affiliation: George Washington University, Department of Forensic Sciences, Washington, District of Columbia.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Moini
authors.forename: Aoife
authors.initials: A
authors.lastname: O'Halloran
authors.forename: Alan M
authors.initials: AM
authors.lastname: Peters
authors.forename: Christine A M
authors.initials: CA
authors.lastname: France
authors.forename: Edward P
authors.initials: EP
authors.lastname: Vicenzi
authors.forename: Tamsen G
authors.initials: TG
authors.lastname: DeWitt
authors.forename: Esther
authors.initials: E
authors.lastname: Langan
authors.forename: Tim
authors.initials: T
authors.lastname: Walsh
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Speakman
mesh_terms: D060105:Animal Shells / Q000737:chemistry* / Q000254:growth & development*; D000818:Animals; D000836:Animals, Zoo; D001966:Bromine / Q000032:analysis; D003300:Copper / Q000032:analysis; D004032:Diet; D013058:Mass Spectrometry / Q000662:veterinary; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D049850:Nautilus / Q000254:growth & development*; D012623:Seawater / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission / Q000662:veterinary; D014961:X-Ray Diffraction / Q000662:veterinary; D015032:Zinc / Q000032:analysis
chemical_list: D003300:Copper; D015032:Zinc; D001966:Bromine
keywords: Mollusca; black line; cephalopods; isotopic abundances; shell formation