The Influence of Water Temperature Upon the Life of the Dog-Whelk Thais lapillus (Gastropoda: Prosobranchia)

1. Thais lapillus becomes active at 3 degrees C and spawning begins at 9-10 degrees C. Crawling and feeding rates reach a maximum at approximately 20 degrees C and both are considerably reduced at 25 degrees C. The species becomes comatose at 27-28 degrees C. 2. Under natural conditions most shell growth occurs during the summer months and seasonal variations in the rate of growth are probably determined largely by changes in the water temperature. 3. A comparison is made between the critical temperatures and geographical distribution for T. lapillus and the related species Urosalpinx cinerea.