Growth
S. luhuanus undergoes determinate growth, whereby juveniles add new material to the edge of the outer lip of the shell and growth terminates when maturity is reached (Savazzi, 1991). This growth occurs in a spiral direction to the right (figure 1). As juveniles, the lip of the shell remains at a constant 0.5mm thick (Catterall and Poiner, 1983). Once maturity is reached at approximately two years, they stop growing lengthwise, and the outer lip thickens to several millimietres thick and there is a slight flaring outwards of the lip (Savazzi, 1991). Growth rates are determined by the specific sites that the individuals are located in (Catterall and Poiner, 1983).
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Figure 1: S. luhuanus in the field. Note that the direction of shell growth is to the right from the perspective of the individual |
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