Studies on the Shipworms I : The Occurrence and Seasonal Settlement of Shipworms.

Abstract

The previous investigation on the occurrence of shipworms in December, 1971 indicated the co-existence of three species of shipworms: Bankia bipalmulata LAMARCK, Teredo navalis LINNAEUS and Lyrodus pedicellatus QUATREFAGES. However, the absence of B. bipalmulata was found in this investigation carried out from February, 1971 to January, 1972. Of these three species, T. navalis was the commonest. In this survey of larval settlement on floating wood surfaces, there was no settlement from January to May, and the first settlement of larvae was not observed until June, when water temperature was over 20℃. The explosive settlement was observed in September. After June, boring damage always occurred when wood blocks were submerged in the sea for over 60 days.