A whole-animal bioassay for the determination of the food attractants of the lobster Homarus gammarus

A semi-quantitative assay is described for assessing the effectiveness of bait extracts for the lobster Homarus gammarus (L.), using an extract of the squid Loligo vulgaris Lamarck as a standard. Fractionation of this extract indicated that, while no single component was as attractive to lobsters as the whole, the recombination of the various components yielded a solution which was as attractive as the original extract. It appears likely that several different classes of chemosensory cell must be simultaneously stimulated for the initiation of feeding behaviour in the lobster.     

Studies on the cytolytic effects of seastar (Marthasterias glacialis) saponins and synthetic surfactants in the plaice Pleuronectes platessa

The toxic effects of Marthasterias glacialis (L.) saponins and synthetic surface-active agents were studied using the plaice Pleuronectes platessa L. as test animal. Solutions of M. glacialis saponins caused considerable, although non-uniform, damage to the gill epithelium, death resulting from a disturbance in the levels of oxygen, carbon dioxide, and sodium ions in the tissues and blood. Histological examination showed that solutions of the synthetic surfactants caused less damage to the gill epithelium than did the M. glacialis saponins. There was a linear relationship between the logarithm of the median haemolytic concentration and the logarithm of the median lethal concentration for the synthetic surfactants. Haemolytic inhibition experiments suggest that the M. glacialis saponins damage cell membranes by interacting with membrane cholesterol.