290
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
(1951) and Hepper (1953), primarily the former. Grainger has shown
that eggs of M . intestinalis hatched in sea water can be satisfactorily
maintained in Petri dishes without aeration. When such preparations
are maintained a t 13-14"C, first copepodids will develop within 40 h
and will survive up to 11 days after reaching that stage. Nauplii,
metanauplii and first copepodids can be maintained in sea water that
has been passed through a Berkefeld filter so that all diatoms, protozoa
and other microorganisms have been removed. Grainger has concluded
from such observations that the development of M . intestinalis from
egg through the first copepodid is independent of ambient nutrients
and derives its energy from the metabolism of nutrients stored within
the body.
Hepper (1953) has demonstrated that eggs of this copepod will
hatch and develop to what may be assumed to be the first copepodid
stage maintained in sea water a t 18°C.
Pathology. It is known that LW. intestinalis has an adverse effect on
Nytilus edulis and may even cause mass mortalities (Cole and Savage,
1951 ; Korringa, 1951b, 1953,1954). Cole and Savage have demonstrated
that among the 5.5-5.9 cm (shell length) group of mussels there is an
inverse relationship between the condition of the mussels and the mean
number of parasites per mussel and the mean number of parasites over
1.5 mm per mussel. The mean weight of mussels between 5 5 - 5 9 cm
long is 3.206 g among parasitized ones and 5.975 g among non-parasitized ones. Personal communications with various individuals have
indicated that the adverse effect of M . intestinalis on Ostrea edulis is
not as severe, although casual observations indicate that the condition
of parasitized oysters is also affected to some extent.
According t o Chew et al. (1963), Korringa (1950a) is said t o have
reported extensive mortalities in commercial mussel beds in Europe
due to parasitization by this copepod.
2. Mytilicola orientalis Mori, 1935. (Figs. 189-191)
(Order Cyclopoida ; family Clausidiidae)
The second species of Mytilicola, M . orientalis, was described by
Mori (1935) from the digestive tract of Crassostrea gigas (Fig. 189) and
Mytilus crassitesta collected from the Inland Sea of Japan. Mori, in
following Steuer, believed that this species is a member of the family
Dichelestiidae, a caligoid family which includes copepods parasitic in
sturgeons and marine teleosts. However) I am in agreement with
Grainger (1951) that the genus Mytilicola belongs in the cyclopoid
family Clausidiidae.
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
(1951) and Hepper (1953), primarily the former. Grainger has shown
that eggs of M . intestinalis hatched in sea water can be satisfactorily
maintained in Petri dishes without aeration. When such preparations
are maintained a t 13-14"C, first copepodids will develop within 40 h
and will survive up to 11 days after reaching that stage. Nauplii,
metanauplii and first copepodids can be maintained in sea water that
has been passed through a Berkefeld filter so that all diatoms, protozoa
and other microorganisms have been removed. Grainger has concluded
from such observations that the development of M . intestinalis from
egg through the first copepodid is independent of ambient nutrients
and derives its energy from the metabolism of nutrients stored within
the body.
Hepper (1953) has demonstrated that eggs of this copepod will
hatch and develop to what may be assumed to be the first copepodid
stage maintained in sea water a t 18°C.
Pathology. It is known that LW. intestinalis has an adverse effect on
Nytilus edulis and may even cause mass mortalities (Cole and Savage,
1951 ; Korringa, 1951b, 1953,1954). Cole and Savage have demonstrated
that among the 5.5-5.9 cm (shell length) group of mussels there is an
inverse relationship between the condition of the mussels and the mean
number of parasites per mussel and the mean number of parasites over
1.5 mm per mussel. The mean weight of mussels between 5 5 - 5 9 cm
long is 3.206 g among parasitized ones and 5.975 g among non-parasitized ones. Personal communications with various individuals have
indicated that the adverse effect of M . intestinalis on Ostrea edulis is
not as severe, although casual observations indicate that the condition
of parasitized oysters is also affected to some extent.
According t o Chew et al. (1963), Korringa (1950a) is said t o have
reported extensive mortalities in commercial mussel beds in Europe
due to parasitization by this copepod.
2. Mytilicola orientalis Mori, 1935. (Figs. 189-191)
(Order Cyclopoida ; family Clausidiidae)
The second species of Mytilicola, M . orientalis, was described by
Mori (1935) from the digestive tract of Crassostrea gigas (Fig. 189) and
Mytilus crassitesta collected from the Inland Sea of Japan. Mori, in
following Steuer, believed that this species is a member of the family
Dichelestiidae, a caligoid family which includes copepods parasitic in
sturgeons and marine teleosts. However) I am in agreement with
Grainger (1951) that the genus Mytilicola belongs in the cyclopoid
family Clausidiidae.