A mature male Risso's dolphin (Grampus griseus) stranded along the coasts of Friuli Venezia Giulia, northeast Italy, in May 2001. Parasitic infection with Crassicauda grampicola is often found in the tympanic bullae and pterygoid sinuses in many of the Risso's dolphins examined from the same area. For this reason, it was decided to perform computed tomography of the head to assess this imaging technique for the diagnosis of crassicaudosis in dolphins. A full postmortem examination confirmed the pathologic findings of the computed tomography scan. This technique can be considered a useful adjunct in the diagnosis of cranial crassicaudosis in live dolphins.

The visual abilities of Zosterisessor ophiocephalus, an ambushing predator inhabiting the intertidal seagrass meadows of lagoons, were studied by morphological and behavioural methods. In its retina, a high number of rods, double and single cones packed in a square mosaic were found, together with the retinomotor response involving the pigment granules and both kinds of photoreceptors. The retinal topography was made by analysing the cone density and density of cells in the ganglion cell layer, and it revealed the area centralis in the dorso-temporal region of the retina. ) on its visual abilities for prey detection was found by comparing the detection and capture efficiencies and the detection and capture distance. A preference for larger food targets was observed. Two capture strategies are described: fast direct and slower hopping capture, the latter exhibited with higher frequency under dim light. Histological visual acuity was 7' and behavioural visual acuity was 15'. The morphological and behavioural studies showed that Z. ophiocephalus can use vision for feeding in bright and dim light conditions, but it probably feeds more at dusk to avoid predators.KEY WORDS: Retina -Retinal topography -Light intensity and behaviour -Visual acuity -Lagoon. ACKNOWLEDGEMENTS

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The mammalian bilirubin transporter bilitranslocase (BTL, T.C.#2.A.65.1.1) is found in both absorptive (intestine) and excretory epithelia (liver, kidney) and in the vascular endothelium. The aim of this work was to investigate whether a BTL homologue is expressed also in fish hepatopancreas. Immunochemistry based on an antisequence antibody specific for rat liver BTL demonstrated the presence of such homologue in sea-bass (Dicentrarchus labrax) hepatopancreas. Furthermore the transport activity of such a carrier, measured as electrogenic bromosulphophthalein (BSP) uptake, was assayed in sea-bass microsomes, where it was inhibited by the same antibody. Transport activity in fish showed numerous kinetic similarities with rat, such as BSP K m (about 5 lM in both), bilirubin K i (about 0.1 lM), quercetin competitive K i (about 20 lM), and noncompetitive K i (about 85 lM). Biliverdin K i was instead nearly 10-fold higher in fish than in rat (0.97 AE 0.06 lM and 0.11 AE 0.01 lM, respectively). Fish BTL was found to exist in two different allosteric forms with different affinities for the substrate, similarly to rat liver BTL. It was found that sea-bass BTL is very sensitive to inhibition by HgCl 2 , a major water pollutant, making it reasonable to exploit fish BTL activity as an ecotoxicological biosensor.