REARING OF BIVALVE MOLLUSKS
129
Imai et al. (1950b) gave a table showing growth of T. navcdis Iarvcle
from day to day, indicating length-width relationships during different
stages of growth. These data closely resemble ours. Other observations
of these authors on appearance and behavior of larvaa are also in close
tlgreement with ours.
Larvae of T . navalis are extremely active and usually swim vigorously and virtually continuously. This is particularly true of younger
stages. We noticed that the larvae have some substance on the outside
of their shells by means of which they adhere readily to glassware
and, as a result, it is extremely difficult to rinse them from beakers,
pipettes, slides, etc.
Larvae began to metamorphose soon after a length of 2 0 0 p was
reaohed. However, several fully-metamorphosed individuals measuring
only 190 p in length and 206 p in width were seen. The largest swimming larvae were approximately 200 x 231 p. Our maximum size of
free-swimming larvae of the wood-borer is, therefore, somewhat
smaller than the 220 x 250 p reported by Sullivan (1948), but closely
approaches that given by Imai et al. (1950).
Larvae of advanced stages do not develop an ‘* eye ” that is
characteristic of larvae of corresponding stages of other species, such
as C. virginica. The foot of recently set borers is extrcmely slender
and worm-like. The set attach themselves to the substratum by
means of a byssus.
The time required for larvae in our cultures to reach metamorphosis
varied. Early in our work, before good food organisms became available, the first metamorphosing larvae were observed 20 days after
swarming, when grown at room temperature. If better growing conditions were provided, the free-swimming pcriod could undouhtodly
be shortened. Nevertheless, we strongly disagree with the conclusions
of Lane et al. (1954) that the normal free-awimming period of Teredo
larvae does not exceed 4 days.
Such
infections were observed on numerous occasions and were probably
responsible for the complete mortalities of Teredo larvae in some of
our cultures.
Teredo larvae are quite susceptible to fungus diseases.
VI. ACKNOWLE DQME NTS
Our studies, which provided most of the material for thig articln,
have been continuous since 1944 and, nrrturally, during t h i H timct
many people have participatod eithcr directly or indircctly. Wc want
to express our appreciation to all biologists of our laboratory, especially
to Mr. Paul E. Chanley, who grew larvae of the several species of
129
Imai et al. (1950b) gave a table showing growth of T. navcdis Iarvcle
from day to day, indicating length-width relationships during different
stages of growth. These data closely resemble ours. Other observations
of these authors on appearance and behavior of larvaa are also in close
tlgreement with ours.
Larvae of T . navalis are extremely active and usually swim vigorously and virtually continuously. This is particularly true of younger
stages. We noticed that the larvae have some substance on the outside
of their shells by means of which they adhere readily to glassware
and, as a result, it is extremely difficult to rinse them from beakers,
pipettes, slides, etc.
Larvae began to metamorphose soon after a length of 2 0 0 p was
reaohed. However, several fully-metamorphosed individuals measuring
only 190 p in length and 206 p in width were seen. The largest swimming larvae were approximately 200 x 231 p. Our maximum size of
free-swimming larvae of the wood-borer is, therefore, somewhat
smaller than the 220 x 250 p reported by Sullivan (1948), but closely
approaches that given by Imai et al. (1950).
Larvae of advanced stages do not develop an ‘* eye ” that is
characteristic of larvae of corresponding stages of other species, such
as C. virginica. The foot of recently set borers is extrcmely slender
and worm-like. The set attach themselves to the substratum by
means of a byssus.
The time required for larvae in our cultures to reach metamorphosis
varied. Early in our work, before good food organisms became available, the first metamorphosing larvae were observed 20 days after
swarming, when grown at room temperature. If better growing conditions were provided, the free-swimming pcriod could undouhtodly
be shortened. Nevertheless, we strongly disagree with the conclusions
of Lane et al. (1954) that the normal free-awimming period of Teredo
larvae does not exceed 4 days.
Such
infections were observed on numerous occasions and were probably
responsible for the complete mortalities of Teredo larvae in some of
our cultures.
Teredo larvae are quite susceptible to fungus diseases.
VI. ACKNOWLE DQME NTS
Our studies, which provided most of the material for thig articln,
have been continuous since 1944 and, nrrturally, during t h i H timct
many people have participatod eithcr directly or indircctly. Wc want
to express our appreciation to all biologists of our laboratory, especially
to Mr. Paul E. Chanley, who grew larvae of the several species of