Shell growth and chamber formation of aquarium‐reared Nautilus pompilius (Mollusca, Cephalopoda) by X‐ray analysis

Abstract

Observations on the growth rate of aquarium maintained Nautilus pompilius in different developmental stages, i.e. juveniles (shell length about 8.75 cm), late juveniles (approximately 10 cm), and early adolescent (approximately 13.5 cm), indicate that this species is fully grown at an age of 7.3-8 years. The age calculations are based on two different computations: (1) the measurement of the increase of the shell length per day and (2) the formation of new septa in time intervals of 150+/-5 days, as demonstrated by X-ray analyses. After N. pompilius hatches, its shell grows about 139 mm to reach full growth and approximately 28 septa are formed. With an increase of the shell length of 0.052 mm per day, it takes about 2,673 days (7.3 years) to reach maturity. Provided that the process of chamber formation follows an exponential function, these computations result in approximately 2,925 days (8 years) to reach full maturity. Supposing that N. pompilius may live for several years after onset of maturity like Nautilus belauensis, the total life span for this species may exceed 11-12 years.

Ammonoid Septa and Sutures

“…However, the precipitation of a septum takes about 105-180 days, according to Ward and Chamberlain (1983) as well as Ward (1985), both of which used radiographic examinations, and by Cochran et al (1981), Landman and Cochran (1987), as well as Landman et al (1989aLandman et al ( , 1989b by indirect radiometric dating of live-caught specimens. Their findings are summarized by Westermann et al (2004). For comparison, the septum formation in Sepia takes only 2-3 days (Boletzky and Wiedmann 1978, Wiedmann and Boletzky 1983, Tanabe et al 1985.…”

“…Exact data for ammonoids are not available yet. During ontogeny, the time of successive chamber formation and septal formation increases (Westermann et al 2004). Oba et al (1992) demonstrated that mineralization of the septum was a continuous process for Nautilus, and they detected small scale cycles (15-40 µm) in the oxygen isotope composition of a single incomplete 1.53 mm thick Nautilus septum measured in analytical intervals of 50 µm and 5 µm.…”

Ethical and welfare considerations when using cephalopods as experimental animals

“…Similarly, the period required for an individual animal to reach sexual maturity varies across species and individuals with a range of 2.5-15 years. Other studies by Ward (1983) and Westermann et al (2004) review laboratory growth rates for N. macromphalus and N. pompilius, respectively and relate them to wild caught animals for age estimation.…”

Genetic diversity of isolated populations of Nautilus pompilius (Mollusca, Cephalopoda) in the Great Barrier Reef and Coral Sea

“…The biology Suzuki et al 2000;Springer et al 2004;Boyle and Rodhouse 2005), sensory chemotaxis (Basil et al 2000(Basil et al , 2005Ruth et al 2002; and functional morphology (Wani 2004;Westermann et al 2004 of Nautilus pompilius have been well described. It is known that Nautilus are generally found among the coral reefs of the Indo-Pacific, where they are not only predators (like their remote ancestors), but they also scavenge on detrital matter settling on the reef bottom.…”