The Species of Teredo From Plymouth Waters

Abstract

In the many references to Teredo from Plymouth early workers assumed that the common form was T. navalis L. Orton (1913) refers to this species, but he has recently told me that he did not try to identify the species precisely. It is almost certain that he was dealing with T. norvegica Spengler, which, it is now known, is the common large species in these waters. Harington (1922) ascribes the species with which he worked at Plymouth to T. norvegica, with a query, and no doubt he identified the species correctly. Yonge (1926) states that the Teredo with which he worked from the experimental raft near Plymouth Breakwater were probably all T. norvegica. Later he identified them as that species. Unlike T. navalis it does not carry its young in a brood pouch, but sends its eggs directly into the sea.Three species have been found in recent years from the Plymouth district, two from the experimental raft moored near the Breakwater and from other fixed wood, and one from driftwood. The two commonly occurring from the raft are (1) T. norvegica and (2) a much smaller species carrying its young in a brood pouch, closely related to, if not identical with, T. navalis. The third species, occurring occasionally in driftwood, is T. megotara Forbes & Hanley. Purchon (1941), who worked at the last species from specimens in a tank at the Plymouth Laboratory, saw no sign of a brood pouch; and in those collected later from Wembury and examined by myself it was found that the eggs, shed directly into the sea, were very numerous.