Oxygen Isotope Variability within Nautilus Shell Growth Bands.

Nautilus is often used as an analogue for the ecology and behavior of extinct externally shelled cephalopods. Nautilus shell grows quickly, has internal growth banding, and is widely believed to precipitate aragonite in oxygen isotope equilibrium with seawater. Pieces of shell from a wild-caught Nautilus macromphalus from New Caledonia and from a Nautilus belauensis reared in an aquarium were cast in epoxy, polished, and then imaged. Growth bands were visible in the outer prismatic layer of both shells. The thicknesses of the bands are consistent with previously reported daily growth rates measured in aquarium reared individuals. In situ analysis of oxygen isotope ratios using secondary ion mass spectrometry (SIMS) with 10 µm beam-spot size reveals inter- and intra-band δ18O variation. In the wild-caught sample, a traverse crosscutting 45 growth bands yielded δ18O values ranging 2.5‰, from +0.9 to -1.6 ‰ (VPDB), a range that is larger than that observed in many serial sampling of entire shells by conventional methods. The maximum range within a single band (~32 µm) was 1.5‰, and 27 out of 41 bands had a range larger than instrumental precision (±2 SD = 0.6‰). The results from the wild individual suggest depth migration is recorded by the shell, but are not consistent with a simple sinusoidal, diurnal depth change pattern. To create the observed range of δ18O, however, this Nautilus must have traversed a temperature gradient of at least ~12°C, corresponding to approximately 400 m depth change. Isotopic variation was also measured in the aquarium-reared sample, but the pattern within and between bands likely reflects evaporative enrichment arising from a weekly cycle of refill and replacement of the aquarium water. Overall, this work suggests that depth migration behavior in ancient nektonic mollusks could be elucidated by SIMS analysis across individual growth bands.

A study of the type series of Nautilus pompilius Linnaeus, 1758 (Mollusca, Cephalopoda, Nautilida).

Few animals are treasured by zoologists more than Nautilus, and Nautilus pompilius Linnaeus, 1758, the type species of the genus, in particular. However, the type series of this species has not been studied in great detail. According to the rules of zoological nomenclature the type series consists of all the specimens included by the author in the new nominal taxon at the time of description (whether directly or by bibliographic reference), and any evidence, published or unpublished, may be taken into account to determine what specimens are included. The type series of Nautilus pompilius includes specimens in the Linnean Society of London, the University Museum in Uppsala, and specimens figured by pre-Linnaean authors indicated by reference by Linnaeus (1758). One specimen in London and four specimens in Uppsala, which are still extant, are likely to have been known to Linnaeus at the time when he prepared the 10th Edition of Systema Naturae (Linnaeus 1758), although none of these specimens was specifically mentioned by him. Even though it is widely believed that Linnaeus (1767) designated as lectotype a specimen figured by Rumphius (1705) in his D'Amboinsche Rariteitkamer, referred to in the Systema Naturae, this presumed lectotypification is not valid because Linnaeus did not explicitly indicate that any particular specimen was considered to be the type of the species. Later lectotype designations of Rumphius' illustrations are invalid because they show three different specimens. It seems that the best approach, given the quality of the material and the lack of clarity as to its type status, would be to apply to the ICZN asking to set aside all previous type fixations and designate a neotype, preferably a DNA sequenced specimen of known provenance.

Comparative population assessments of Nautilus sp. in the Philippines, Australia, Fiji, and American Samoa using baited remote underwater video systems.

The extant species of Nautilus and Allonautilus (Cephalopoda) inhabit fore-reef slope environments across a large geographic area of the tropical western Pacific and eastern Indian Oceans. While many aspects of their biology and behavior are now well-documented, uncertainties concerning their current populations and ecological role in the deeper, fore-reef slope environments remain. Given the historical to current day presence of nautilus fisheries at various locales across the Pacific and Indian Oceans, a comparative assessment of the current state of nautilus populations is critical to determine whether conservation measures are warranted. We used baited remote underwater video systems (BRUVS) to make quantitative photographic records as a means of estimating population abundance of Nautilus sp. at sites in the Philippine Islands, American Samoa, Fiji, and along an approximately 125 km transect on the fore reef slope of the Great Barrier Reef from east of Cairns to east of Lizard Island, Australia. Each site was selected based on its geography, historical abundance, and the presence (Philippines) or absence (other sites) of Nautilus fisheries The results from these observations indicate that there are significantly fewer nautiluses observable with this method in the Philippine Islands site. While there may be multiple possibilities for this difference, the most parsimonious is that the Philippine Islands population has been reduced due to fishing. When compared to historical trap records from the same site the data suggest there have been far more nautiluses at this site in the past. The BRUVS proved to be a valuable tool to measure Nautilus abundance in the deep sea (300-400 m) while reducing our overall footprint on the environment.

Understanding irregular shell formation of Nautilus in aquaria: chemical composition and structural analysis.

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.

Transcriptome analysis of Nautilus and pygmy squid developing eye provides insights in lens and eye evolution.

Coleoid cephalopods like squids have a camera-type eye similar to vertebrates. On the other hand, Nautilus (Nautiloids) has a pinhole eye that lacks lens and cornea. Since pygmy squid and Nautilus are closely related species they are excellent model organisms to study eye evolution. Having being able to collect Nautilus embryos, we employed next-generation RNA sequencing using Nautilus and pygmy squid developing eyes. Their transcriptomes were compared and analyzed. Enrichment analysis of Gene Ontology revealed that contigs related to nucleic acid binding were largely up-regulated in squid, while the ones related to metabolic processes and extracellular matrix-related genes were up-regulated in Nautilus. These differences are most likely correlated with the complexity of tissue organization in these species. Moreover, when the analysis focused on the eye-related contigs several interesting patterns emerged. First, contigs from both species related to eye tissue differentiation and morphogenesis as well as to cilia showed best hits with their Human counterparts, while contigs related to rabdomeric photoreceptors showed the best hit with their Drosophila counterparts. This bolsters the idea that eye morphogenesis genes have been generally conserved in evolution, and compliments other studies showing that genes involved in photoreceptor differentiation clearly follow the diversification of invertebrate (rabdomeric) and vertebrate (ciliated) photoreceptors. Interestingly some contigs showed as good a hit with Drosophila and Human homologues in Nautilus and squid samples. One of them, capt/CAP1, is known to be preferentially expressed in Drosophila developing eye and in vertebrate lens. Importantly our analysis also provided evidence of gene duplication and diversification of their function in both species. One of these genes is the Neurofibromatosis 1 (NF1/Nf1), which in mice has been implicated in lens formation, suggesting a hitherto unsuspected role in the evolution of the lens in molluscs.

Nautilus: craniotomia dinâmica - nova técnica cirúrgica e resultados preliminares / Nautilus-shaped dynamic craniotomy: a new surgical technique and preliminary results

INTRODUÇÃO: Considerando-se que as craniossinostoses são afecções basicamente suturais, o fato de o cérebro estar aprisionado em um compartimento fechado, que não possui a complacência necessária para acompanhar seu crescimento, se constitui no desafio principal de seu tratamento. O objetivo do tratamento é restabelecer a complacência da sutura estenótica e corrigir a deformidade craniana compensatória. Este trabalho propõe a associação de osteotomia helicoide à distração osteogênica proporcionada pelo uso das molas distratoras para remodelar defeitos craniofaciais causados por craniossinostoses. MÉTODO: Entre julho de 2010 e julho de 2012, foram tratados 10 pacientes portadores de craniossinostoses, sendo 5 oxicefalias, 3 escafocefalias, 1 turricefalia e 1 trigonocefalia. O tratamento consistiu na aplicação de molas de Lauritzen, para corrigir a deformidade primária da craniossinostose, com a associação de craniotomia helicoide em forma de Nautilus nos sítios de deformação secundária do crânio, sem descolamento dural. RESULTADOS: Foi observada resolução da deformidade craniana e remissão dos sinais clínicos de hipertensão intracraniana. Nenhum paciente apresentou complicações, como fístula liquórica, infecção local, seroma ou hematoma. CONCLUSÕES: A associação da osteotomia helicoide com a distração ou contração promovida pelas molas permitiu remodelar ativamente o crânio, facilitando a acomodação do conteúdo cerebral no continente craniano.

INTRODUCTION: Considering that craniosynostosis is a suture-related condition, the main challenge for its treatment is the fact that the brain is located in a closed compartment that does not have the required adaptability to accommodate its growth. The goal of treatment is to restore stenotic suture adaptability and correct the compensatory cranial deformity. This paper proposes the combined use of spiral osteotomy with distraction osteogenesis by the use of distracting springs to remodel craniofacial defects caused by craniosynostosis. METHODS: Between July 2010 and July 2012, 10 patients with craniosynostosis were treated: 5 with oxycephaly, 3 with scaphocephaly, 1 with turricephaly, and 1 with trigonocephaly. The treatment consisted of the application of Lauritzen springs to correct the primary craniosynostosis defect in combination with a nautilus-shaped spiral craniotomy at the secondary deformation sites without dural detachment. RESULTS: Resolution of cranial deformity and remission of the clinical signs of intracranial hypertension were observed. None of the patients had complications such as cerebrospinal fluid fistula, local infection, seroma, or hematoma. CONCLUSIONS: The combined use of spiral osteotomy with spring-mediated distraction or contraction enables active reshaping of the skull and facilitates accommodation of the brain by the cranial cavity.

Nautilus pompilius life history and demographics at the Osprey Reef Seamount, Coral Sea, Australia.

Nautiloids are the subject of speculation as to their threatened status arising from the impacts of targeted fishing for the ornamental shell market. Life history knowledge is essential to understand the susceptibility of this group to overfishing and to the instigation of management frameworks. This study provides a comprehensive insight into the life of Nautilus in the wild. At Osprey Reef from 1998-2008, trapping for Nautilus was conducted on 354 occasions, with 2460 individuals of one species, Nautilus pompilius, captured and 247 individuals recaptured. Baited remote underwater video systems (BRUVS) were deployed on 15 occasions and six remotely operated vehicle (ROV) dives from 100-800 m were conducted to record Nautilus presence and behavior. Maturity, sex and size data were recorded, while measurements of recaptured individuals allowed estimation of growth rates to maturity, and longevity beyond maturity. We found sexual dimorphism in size at maturity (males: 131.9±SD = 2.6 mm; females: 118.9±7.5 mm shell diameter) in a population dominated by mature individuals (58%). Mean growth rates of 15 immature recaptured animals were 0.061±0.023 mm day(-1) resulting in an estimate of around 15.5 years to maturation. Recaptures of mature animals after five years provide evidence of a lifespan exceeding 20 years. Juvenile Nautilus pompilius feeding behavior was recorded for the first time within the same depth range (200-610 m) as adults. Our results provide strong evidence of a K-selected life history for Nautilus from a detailed study of a 'closed' wild population. In conjunction with population size and density estimates established for the Osprey Reef Nautilus, this work allows calculations for sustainable catch and provides mechanisms to extrapolate these findings to other extant nautiloid populations (Nautilus and Allonautilus spp.) throughout the Indo-Pacific.