Radular production rates in two species of Lacuna turton (Gastropoda: Littorinidae)

The molluscan radula is a dynamic organ, both in terms of its use and production. New rows of teeth are constantly produced at the posterior end of the radula, while older, worn teeth are shed anteriorly, producing a dynamic equilibrium. We used a coldshock to mark the radular ribbon and measure tooth row production rates in two gastropod species. Lacuna vincta (Montagu) and L. variegata Carpenter. We found that the average tooth row production rate at 10-11°C did not differ between these two species, and was 2.94 (SE = 0.002) rows per day for Lacuna vincta and 2.97 (SE = 0.002) for L. variegata. Inter-individual variability in production rate was very low, and was correlated with shell length; smaller individuals had slightly higher production rates. The total length of the radular ribbon varied greatly among individuals, ranging from 47 to 94 (2.57 to 5.68 mm) rows in L. vincta and 53 to 99 rows (2.80 to 7.14 mm) in L. variegata, and was only somewhat correlated with the length of the shell. This great variability will result in large differences among individuals in the time it takes to replace the radula totally, from 14.96 to 35.44 days in L. vincta and from 17.43 to 39.69 days in L. variegata.