Abstract

Five potential relaxant chemical compounds (2-phenoxyethanol, menthol crystals, benzocaine, MS-222, and magnesium chloride) were evaluated to induce relaxation in the queen conch, Strombus gigas, for cultured pearl production. Conch exposed to each chemical were observed continuously for 30 min. Conch were placed on the bottom of a container with the aperture facing upwards (i.e., in an inverted position) and were allowed to return to their 'normal' position and then were turned facing upwards again. This process continued until the conch were unable to return to their normal position. Only 30 g/L MgCl induced adequate relaxation in S. gigas to perform pearl seeding. Conch exposed to all other treatments, except 0.25 g/L menthol, showed a strong 'kicking' reaction during the first minutes of exposure. After such reaction, conch retracted into their shells and within the 30 min exposure period they showed no signs of relaxation. Conch exposed to 0.25 g/L menthol did not attempt to right but slowly retracted into their shells and did not show signs of relaxation. Conch can be relaxed in 15 to 20 min with magnesium chloride. They showed an extended mantle, a relaxed foot and a slow response to physical manipulation

PDF Preview