90
VICTOR L. LOOSANOFF AND HARRY C. DAVIS
E. Mytilw edulis Linn6
A study of the literature on lamellibranch larvae shows that
veligers of M . edulis have been described more frequently than those
of other bivalves. Borisjak (1909) was probably the first to describe
these larvae while, more recently, descriptions of presumably the =me
veligers were given by Jmgensen (1946), Sullivan (1948), Rees (1960)
and others.
Mussels with apparently morphologically-ripe gonads are found in
our waters in early spring, but under laboratory conditions, using our
method of maturing animals in warm water, ripe mussels can be made
available in January.
Field (1922) reported that rough handling of mussels, such as
shaking them in a dish of sea water, will induce spawning within an hour,
but Costello et al. (1957) found this method unsuccessful. In our case,
during studies conducted for 3 yr, except for brief periods in April
and early May, all efforts usually employed to stimulate bivalves to
spawn failed to work with M . edulis. These included sharp incremes
or decreases in temperature, addition of sex products to the water,
keeping mussels in air overnight, placing them in refrigerators for
various periods, increasing or decreasing salinity of the water, and even
applying light electrical shocks. This was true also of mussels that
were conditioned in the laboratory for a considerable time and whose
gonads appeared to be morphologically ripe.
Fortunately, it w4s noticed by two of our associates, first, W. Arcisz,
and several years later, J. Uzmann, that some ripe female mussels
released large numbers of eggs after their adductor muscles were cut.
These observations suggested a number of experiments on inducing
spawning in mussels. The first attempt consisted of opening a large
number of these mollusks and placing each individual in a separate
vessel. The results were rather gratifying because, in the majority
of cases, the mussels discharged large quantities of normal sex products.
The method worked even on mussels that were not laboratory conditioned. For example, on 26 April 1951, mussels were brought in
from Milford Harbor, where the water temperature waa 8°C. The
adductor muscles of twelve females were severed and the mussels
were placed in water at room temperature. The first two females
spawned within 12 hr; four others deposited masses of eggs within
24 hr, and six remaining females released eggs toward the end of the
48-hr period. This experiment was repeated on several occasions
giving virtually the same results.
Eggs released by females with severed muscles were usually discharged in " strings ", as occurs in normal spawning. The majority
VICTOR L. LOOSANOFF AND HARRY C. DAVIS
E. Mytilw edulis Linn6
A study of the literature on lamellibranch larvae shows that
veligers of M . edulis have been described more frequently than those
of other bivalves. Borisjak (1909) was probably the first to describe
these larvae while, more recently, descriptions of presumably the =me
veligers were given by Jmgensen (1946), Sullivan (1948), Rees (1960)
and others.
Mussels with apparently morphologically-ripe gonads are found in
our waters in early spring, but under laboratory conditions, using our
method of maturing animals in warm water, ripe mussels can be made
available in January.
Field (1922) reported that rough handling of mussels, such as
shaking them in a dish of sea water, will induce spawning within an hour,
but Costello et al. (1957) found this method unsuccessful. In our case,
during studies conducted for 3 yr, except for brief periods in April
and early May, all efforts usually employed to stimulate bivalves to
spawn failed to work with M . edulis. These included sharp incremes
or decreases in temperature, addition of sex products to the water,
keeping mussels in air overnight, placing them in refrigerators for
various periods, increasing or decreasing salinity of the water, and even
applying light electrical shocks. This was true also of mussels that
were conditioned in the laboratory for a considerable time and whose
gonads appeared to be morphologically ripe.
Fortunately, it w4s noticed by two of our associates, first, W. Arcisz,
and several years later, J. Uzmann, that some ripe female mussels
released large numbers of eggs after their adductor muscles were cut.
These observations suggested a number of experiments on inducing
spawning in mussels. The first attempt consisted of opening a large
number of these mollusks and placing each individual in a separate
vessel. The results were rather gratifying because, in the majority
of cases, the mussels discharged large quantities of normal sex products.
The method worked even on mussels that were not laboratory conditioned. For example, on 26 April 1951, mussels were brought in
from Milford Harbor, where the water temperature waa 8°C. The
adductor muscles of twelve females were severed and the mussels
were placed in water at room temperature. The first two females
spawned within 12 hr; four others deposited masses of eggs within
24 hr, and six remaining females released eggs toward the end of the
48-hr period. This experiment was repeated on several occasions
giving virtually the same results.
Eggs released by females with severed muscles were usually discharged in " strings ", as occurs in normal spawning. The majority