Based on 1,260 samples, the age and growth of purple whelk, Rapana venosa (Valenciennes) (Gastropoda:Muricidae) have been investigated. The samples were collected monthly during one year time (from February, 2004 to January, 2005) from the West Sea of Korea. The age of R. venosa was determined by the ring of the operculum analysis. The relationship between whelk’s shell height and ring radius in each ring group was expressed as an equation of linear regression and later a correspondence in each ring formation was determined. Based on the monthly variations in the marginal index (MI) of the operculum, it was assumed that the ring of this species has been formed once a year during the period from July to August.
The relationship between shell height and shell width was expressed by the quation SW = 0.7867 SH - 6.3988 (R2=0.8604); and between shell height and total weight by the equation TW=0.0000626×SH3.206 (R2=0.8324).

The purple whelk’s spawning period was estimated through the fatness analysis and has occurred during the period from May to July.

Obtained results suggests that the ring formation occurs once a year (in July) and the length of time period since the first ring has been formed on the operculum is approximately 13 months (1.08 year). The purple whelk’s growth curves for shell height and total weight fitted to the von Bertalanffy's equation and were expressed as follows: