Structure and mineralization of the spearing mantis shrimp (Stomatopoda; Lysiosquillina maculata) body and spike cuticles.

Stomatopoda is a crustacean order including sophisticated predators called spearing and smashing mantis shrimps that are separated from the well-studied Eumalacotraca since the Devonian. The spearing mantis shrimp has developed a spiky dactyl capable of impaling fishes or crustaceans in a fraction of second. In this high velocity hunting technique, the spikes undergo an intense mechanical constraint to which their exoskeleton (or cuticle) has to be adapted. To better understand the spike cuticle internal architecture and composition, electron microscopy, X-ray microanalysis and Raman spectroscopy were used on the spikes of 7 individuals (collected in French Polynesia and Indonesia), but also on parts of the body cuticle that have less mechanical stress to bear. In the body cuticle, several specificities linked to the group were found, allowing to determine the basic structure from which the spike cuticle has evolved. Results also highlighted that the body cuticle of mantis shrimps could be a model close to the ancestral arthropod cuticle by the aspect of its biological layers (epi- and procuticle including exo- and endocuticle) as well as by the Ca-carbonate/phosphate mineral content of these layers. In contrast, the spike cuticle exhibits a deeply modified organization in four functional regions overprinted on the biological layers. Each of them has specific fibre arrangement or mineral content (fluorapatite, ACP or phosphate-rich Ca-carbonate) and is thought to assume specific mechanical roles, conferring appropriate properties on the entire spike. These results agree with an evolution of smashing mantis shrimps from primitive stabbing/spearing shrimps, and thus also allowed a better understanding of the structural modifications described in previous studies on the dactyl club of smashing mantis shrimps.

Advanced photocatalytic oxidation processes for micropollutant elimination from municipal and industrial water.

The objective of this study was to develop and validate an innovative technology to ensure efficient elimination of different types of micropollutants and toxic compounds in waste water. The process is a tertiary treatment process, which can be easily integrated into municipal and industrial waste water treatment plants. It is based on oxidation by ozone and subsequent photocatalytic treatment. After development and validation of this system at laboratory scale, the solution was tested at pilot scale. The first part of this work was to develop a TiO2-based film on glass substrate, characterize its physico-chemical properties and optimize its composition at laboratory scale to be photoactive on the degradation of model water containing several pollutants. The model water consisted of a mixture of 22 major micropollutants including pesticides, plasticizers, brominated compounds, and pharmaceuticals. The best photocatalyst for the degradation of the selected micropollutants was a TiO2 coating doped with 2 wt% of Ag and where 10 wt% P25 was added. Then, in order to scale up the process, its deposition on steel substrates was tested with dip and spray coating at laboratory scale. Calcination parameters were optimized to limit steel corrosion while keeping similar photoactive properties regarding the degradation of the model polluted water. The optimized solution was deposited by spray coating in a pilot scale reactor in order to assess its efficiency in a pilot water treatment plant.

Simultaneous production of two kinds of sounds in relation with sonic mechanism in the boxfish Ostracion meleagris and O. cubicus.

In fishes, sonic abilities for communication purpose usually involve a single mechanism. We describe here the sonic mechanism and sounds in two species of boxfish, the spotted trunkfish Ostracion meleagris and the yellow boxfish Ostracion cubicus. The sonic mechanism utilizes a T-shaped swimbladder with a swimbladder fenestra and two separate sonic muscle pairs. Extrinsic vertical muscles attach to the vertebral column and the swimbladder. Perpendicularly and below these muscles, longitudinal intrinsic muscles cover the swimbladder fenestra. Sounds are exceptional since they are made of two distinct types produced in a sequence. In both species, humming sounds consist of long series (up to 45 s) of hundreds of regular low-amplitude pulses. Hums are often interspersed with irregular click sounds with an amplitude that is ten times greater in O. meleagris and forty times greater in O. cubicus. There is no relationship between fish size and many acoustic characteristics because muscle contraction rate dictates the fundamental frequency. We suggest that hums and clicks are produced by either separate muscles or by a combination of the two. The mechanism complexity supports an investment of boxfish in this communication channel and underline sounds as having important functions in their way of life.