Although the emergence of complex biomineralized forms has been investigated for over a century, still little is known on how single cells control morphology of skeletal structures, such as frustules, shells, spicules, or scales. We have run experiments on the shell formation in foraminifera, unicellular, mainly marine organisms that can build shells by successive additions of chambers. We used live imaging to discover that all stages of chamber/shell formation are controlled by dedicated actin-driven pseudopodial structures. Successive reorganization of an F-actin meshwork, associated with microtubular structures, is actively involved in formation of protective envelope, followed by dynamic scaffolding of chamber morphology. Then lamellar dynamic templates create a confined space and control mineralization separated from seawater. These observations exclude extracellular calcification assumed in selected foraminiferal clades, and instead suggest a semiintracellular biomineralization pattern known from other unicellular calcifying and silicifying organisms. These results give a challenging prospect to decipher the vital effect on geochemical proxies applied to paleoceanographic reconstructions. They have further implications for understanding multiscale complexity of biomineralization and show a prospect for material science applications.

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a b s t r a c t a r t i c l e i n f oO profile, assuming a single-peak annual SST cycle. The magnitude of these oscillations was 5-7°C. Mg/Ca and the growth-banding pattern in the Miocene T. gigas correlates well with shell δ 18O during the later part of the organism's lifespan. Ba/Ca is negatively correlated to Mg/Ca, with a lag of several months, suggesting a different phasing of the annual primary productivity cycle from that of SST. Furthermore, δ 18O and Mg/Ca show prominent deviations to warmer conditions with a periodicity of~3 years. These shifts demonstrate the existence of substantial interannual sea surface temperature variability in the Miocene, a period with elevated global temperatures compared to the present day.

To study the effect of water flow on coral growth, four series of ten coral nubbins of Galaxea fascicularis were exposed to four different flow regimes (0, 10, 20, and 25 cm s-1 , bidirectional flow) for 42 weeks. Buoyant weight, surface area, and polyp number were measured at regular intervals. Net photosynthesis and dark respiration were measured at the corresponding flow speeds, and daily amount of photosynthetic carbon left for coral growth was calculated. Finally, skeletal density and CN content, chlorophyll concentration and dry weight of coral tissue were determined for each coral. Specific growth rate (in day-1) decreased with time in each flow treatment. Absence of flow resulted in significantly lower growth rates. Average specific growth rate calculated over the entire experiment was not significantly different between 10 and 20 cm s-1 , while it was significantly higher at 25 cm s-1. From 10 to 25 cm s-1 , average net photosynthetic rate decreased and average dark respiration rate did not change significantly. Scope for growth based on phototrophic carbon decreased with increasing flow. Growth was not positively correlated with either photosynthesis or respiration, or scope for growth. It is suggested that higher flow rates reduce the chance of disturbance of coral growth by competing algae or cyanobacteria, allowing corals to grow more readily with the maximum specific growth rate possible under the given environmental conditions. Notably, other effects of increased flow, such as increased respiratory rates and increased (in)organic nutrient uptake, might have been equally responsible for the increased growth of the corals in 25 cm s-1 .

1. SECORE (SExual COral REproduction) Project is an initiative of public aquariums and research institutions to produce and exchange sexual coral recruits for the sustainable management of ex situ populations. Here we present the results of the initial three years (2002)(2003)(2004).2. Primary polyps (n=501) of corals (Acropora tenuis, Agaricia humilis, Favia fragum) were transported from Rotterdam Zoo to Cologne, Burgers', Hagenbeck and London Zoos, where development of juveniles was monitored for 10 months. All polyps were produced at Rotterdam Zoo from laboratory colonies (A. humilis, F. fragum), and from larvae generated from field collected gametes at Akajima, Okinawa, Japan (A. tenuis). Additionally, planulae of A. tenuis (n=1440) were transported from Rotterdam Zoo to Burgers' Zoo and to London Zoo to obtain primary polyps.3. Larval settlement (A. tenuis) was observed to be 3.00 AE 2.57% (mean AE SD; n=1480) in 2002 and 17.36 AE 6.01% (mean AE SD; n=1480) in 2003, significantly lower compared to settlement at Rotterdam Zoo (57.84 AE 11.01% in 2003; mean AE SD, n=1480). High post-transport survival rates of 95.18 AE 4.86% (mean AE SD; n=501) were observed in primary polyps of all species. 4. Juvenile survival (t=10 months; A. tenuis: 18.4-86.2%; A. humilis: 0-19.7%; F. fragum: 13.3-72.7%) differed significantly between institutions. Mean colony sizes (measured 10 months after transportation) were, in all cases, similar or higher to those reported from literature.