Patent ID: 7330794

Claim:
A method for installing a mollusk having two shells in a chamber in a system for screening water for the presence of toxicants, said method comprising: affixing an attachment portion to one of the shells of the mollusk; connecting the attachment portion to a support assembly supported in the chamber, said attachment portion and support assembly being configured so that the attachment portion can be released from the support assembly, thereby releasing the mollusk when desired; engaging the other shell of the mollusk with a sensing apparatus detecting a range of positions of the shell, said range of positions including at least a closed position, an open position and an intermediate position therebetween, and generating a periodic or continuous output signal indicative of the position of the shell, the sensing apparatus including a first movable lever having a pivot connection supporting the first movable lever in the chamber for pivoting movement responsive to movement of the shell, the detected position of the shell of the mollusk being dependent on the position of said movable lever, said movable lever having a proximal portion engaging the shell of the mollusk so as to move therewith when the mollusk opens and closes the shell, and a distal portion extending away from the proximal portion beyond the pivot connection, the sensing apparatus further including a biasing structure biasing the movable lever so that the proximal portion engages the shell, said biasing structure applying sufficiently small force to the movable lever such that the movable member does not substantially interfere with the opening or closing movement of the shell; clamping the shells of the mollusk shut; adjusting the sensing apparatus so that said sensing apparatus generates an output in a predetermined range to circuitry, which analyzes said signal such that said signal is as indicative of the gape of said mollusk; and releasing the shells of the mollusk thereby installing a mollusk.