Radula tooth turnover in the chiton, Acanthopleura hirtosa (Blainville, 1825) (Mollusca : Polyplacophora)

The rate of radula production in the chiton Acanthopleura hirtosa (Blainville, 1825) was determined by following structural irregularities induced in the radula using a cold-shock treatment of 4°C for 48 h. In animals treated in this manner and subsequently maintained in an artificial intertidal habitat to ensure, as far as possible, a natural feeding regimen, the rate of radular production was calculated as 0.36 rows per day. This indicates that A. hirtosa renews its total radular length (mean 78 rows, SD = 6.5, n = 23) approximately once every 6.5 months, a relatively slow rate when compared with that of other molluscs.