33
2
Distribution and Composition
of Polydorid Species
Associated with Mollusk Shells
There are numerous polydorids that have been
reported as being associated with commercially
important mollusk shells, i.e., oysters, scallops,
and abalone, in Japan, South Korea, China, and
Australia (Table 1 ). A total of 28 species from
fi ve genera have been reported from these waters
since 1970, during which time the commercial
transportation of mollusk shells has increased.
The percentage composition of the number of
species by genus was 16 species (57 %) in
Polydora , seven species (25 %) in Dipolydora ,
three species (11 %) in Boccardia , and one species (3 %) in each Boccardiella and
Pseudopolydora , respectively. The results show
that over half of the target species belong to the
genus Polydora . Among these, estimates of the
shell infestation condition by Polydora brevipalpa and P. uncinata from Japan (Imajima and
Sato 1984 ; Sato-Okoshi et al. 1990 ; Sato- Okoshi
1994 , 1998 ; Sato-Okoshi and Abe 2012 ); P. haswelli , P. aura , and P. uncinata from South Korea
(Sato-Okoshi et al. 2012 ); P. brevipalpa from
China (Sato-Okoshi et al. 2013 ); and P. uncinata ,
P. hoplura , and Boccardia knoxi from Australia
(Lleonart et al. 2003 ; Sato-Okoshi et al. 2008 ;
Sato-Okoshi and Abe 2012 ) revealed that these
polydorid species should be considered particularly dangerous. To date, Polydora uncinata is the
only species revealed to be harmful across all
these countries, with the exception of China. This
species was reported to be especially harmful in
abalone shells, i.e., land-based tank- cultured
abalone.
3
Morphological, Biological,
and Ecological Characteristics
of the Four Harmful Polydora
Species
Detailed characteristics of the four most harmful
species from the 28 polydorid species are described below. These include Polydora brevipalpa ,
P. uncinata , P. haswelli , and P. aura . Photographs
of living specimens (Fig. 1 ) and the infestation
condition of scallop, oyster, and abalone shells
(Fig. 2 ) are shown.
3.1
Polydora brevipalpa (Fig. 1a, b )
3.1.1 Morphological Characteristics
Large-sized worms. Conspicuous black bands
appear on palps. The anterior end of the prostomium is rounded, and there is no notochaetae in
the 5th chaetiger. The color of the pygidium is
light tan, white, black, or partially black.
3.1.2 Biological and Ecological
Characteristics
The larvae showed planktotrophic development.
The species is distributed in cold waters. It is very
common in scallop shells particularly abundant
in the left valves of wild and sown cultured scallops in the Okhotsk Sea (Fig. 2a ) (Mori et al.
1985 ). Recently, the species was fi rst extracted
from the shells of wild and sown cultured abalone, other than scallop, in north China (SatoOkoshi et al. 2013 ). They reproduce egg capsules
repeatedly, except during seasons of high temperature, and showed high reproductive capacity.
The larvae settle at the periphery of the left valve
of the scallop during drift ice period and their life
span is approximately 2.5 years (Sato-Okoshi
1994 ). Severe infestation by the species was
observed not only in Japanese scallops but also in
Chinese sown cultured scallops (Sato-Okoshi
et al. 2013 ).
3.2
Polydora uncinata (Fig. 1c, d )
3.2.1 Morphological Characteristics
Large-sized worms. Conspicuous black bands
appear on palps and black pigmentation presents on both dorsal and ventral sides of anterior
chaetigers. Rarely no conspicuous black pigmentation is observed on the palps and body.
Short occipital tentacle is present. There are
special recurved notochaetae in posterior
chaetigers.
Harmful Shell Borers, Polydora Species (Polychaeta: Spionidae), from Commercially…
2
Distribution and Composition
of Polydorid Species
Associated with Mollusk Shells
There are numerous polydorids that have been
reported as being associated with commercially
important mollusk shells, i.e., oysters, scallops,
and abalone, in Japan, South Korea, China, and
Australia (Table 1 ). A total of 28 species from
fi ve genera have been reported from these waters
since 1970, during which time the commercial
transportation of mollusk shells has increased.
The percentage composition of the number of
species by genus was 16 species (57 %) in
Polydora , seven species (25 %) in Dipolydora ,
three species (11 %) in Boccardia , and one species (3 %) in each Boccardiella and
Pseudopolydora , respectively. The results show
that over half of the target species belong to the
genus Polydora . Among these, estimates of the
shell infestation condition by Polydora brevipalpa and P. uncinata from Japan (Imajima and
Sato 1984 ; Sato-Okoshi et al. 1990 ; Sato- Okoshi
1994 , 1998 ; Sato-Okoshi and Abe 2012 ); P. haswelli , P. aura , and P. uncinata from South Korea
(Sato-Okoshi et al. 2012 ); P. brevipalpa from
China (Sato-Okoshi et al. 2013 ); and P. uncinata ,
P. hoplura , and Boccardia knoxi from Australia
(Lleonart et al. 2003 ; Sato-Okoshi et al. 2008 ;
Sato-Okoshi and Abe 2012 ) revealed that these
polydorid species should be considered particularly dangerous. To date, Polydora uncinata is the
only species revealed to be harmful across all
these countries, with the exception of China. This
species was reported to be especially harmful in
abalone shells, i.e., land-based tank- cultured
abalone.
3
Morphological, Biological,
and Ecological Characteristics
of the Four Harmful Polydora
Species
Detailed characteristics of the four most harmful
species from the 28 polydorid species are described below. These include Polydora brevipalpa ,
P. uncinata , P. haswelli , and P. aura . Photographs
of living specimens (Fig. 1 ) and the infestation
condition of scallop, oyster, and abalone shells
(Fig. 2 ) are shown.
3.1
Polydora brevipalpa (Fig. 1a, b )
3.1.1 Morphological Characteristics
Large-sized worms. Conspicuous black bands
appear on palps. The anterior end of the prostomium is rounded, and there is no notochaetae in
the 5th chaetiger. The color of the pygidium is
light tan, white, black, or partially black.
3.1.2 Biological and Ecological
Characteristics
The larvae showed planktotrophic development.
The species is distributed in cold waters. It is very
common in scallop shells particularly abundant
in the left valves of wild and sown cultured scallops in the Okhotsk Sea (Fig. 2a ) (Mori et al.
1985 ). Recently, the species was fi rst extracted
from the shells of wild and sown cultured abalone, other than scallop, in north China (SatoOkoshi et al. 2013 ). They reproduce egg capsules
repeatedly, except during seasons of high temperature, and showed high reproductive capacity.
The larvae settle at the periphery of the left valve
of the scallop during drift ice period and their life
span is approximately 2.5 years (Sato-Okoshi
1994 ). Severe infestation by the species was
observed not only in Japanese scallops but also in
Chinese sown cultured scallops (Sato-Okoshi
et al. 2013 ).
3.2
Polydora uncinata (Fig. 1c, d )
3.2.1 Morphological Characteristics
Large-sized worms. Conspicuous black bands
appear on palps and black pigmentation presents on both dorsal and ventral sides of anterior
chaetigers. Rarely no conspicuous black pigmentation is observed on the palps and body.
Short occipital tentacle is present. There are
special recurved notochaetae in posterior
chaetigers.
Harmful Shell Borers, Polydora Species (Polychaeta: Spionidae), from Commercially…