37
3.2.2 Biological and Ecological
Characteristics
Larvae showed direct development and adelphophagy with many nurse eggs within egg capsules.
Their hatched-out stage was ca 17-chaetiger larvae
and showed no or very short planktonic larval
stage. One female seemed to reproduce egg capsules repeatedly and reproduction capacity was
suggested to be very high. Life span was predicted to be more than 2 years in the tank- cultured
environment. The species was distributed widely
in Asian and Australian waters, and it was
extracted commonly from both wild and cultured
mollusk shells. It is noteworthy to cite that a high
number of these species have been suddenly
observed in suspended cultured oyster shells in
South Korea (Fig. 2b ), which is speculated to be
the result of host oysters being introduced from
different waters (Sekino et al. 2003 ; Sato-Okoshi
et al. 2012 ). In addition to Japan and Australia,
heavy infestation of this species has been reported
on land-based tank-cultured abalone in Chile. It
is also speculated that this infestation was the
result of host abalone being transported from
Japan to Chile accompanying the P. uncinata
population (Radashevsky and Olivares 2005 ).
This species is regarded as one of the most dangerous polydorids, especially in the case of
enclosed aquaculture systems such as abalone
land-based tank culture (Fig. 2c ).
3.3
Polydora haswelli (Fig. 1e )
3.3.1 Morphological Characteristics
Medium- to large-sized worms. Conspicuous
black bands appear on palps and black pigmentation presents on both dorsal and ventral sides of
anterior chaetigers.
3.3.2 Biological and Ecological
Characteristics
Larvae revealed planktotrophic development.
Little is currently known about other characteristics, e.g., life history or reproductive
characteristics. Although the species exhibits
medium sizes in Japan, it reaches larger sizes
and is very common in South Korean mollusk
shells (Fig. 2b ) (Sato-Okoshi et al. 2012 ). The
species causes harmful infestations in many
commercially important shells, but appears
limited to South Korea (Sato-Okoshi et al.
2012 ).
Fig. 2 Pictures of shells infested by Polydora species. ( a )
Inner surface of the left valve of scallop shell showing
heavy infestation by P. brevipalpa after removing the
mantle (From Sato-Okoshi and Abe 2012 ). ( b ) Inner surface of the oyster shell showing heavy infestation by P.
uncinata and P. haswelli (From Sato-Okoshi and Okoshi
2014 ). ( c ) Inner surface of the abalone shell showing
heavy infestation by P. uncinata (From Sato-Okoshi et al.
2012 )
Harmful Shell Borers, Polydora Species (Polychaeta: Spionidae), from Commercially…
3.2.2 Biological and Ecological
Characteristics
Larvae showed direct development and adelphophagy with many nurse eggs within egg capsules.
Their hatched-out stage was ca 17-chaetiger larvae
and showed no or very short planktonic larval
stage. One female seemed to reproduce egg capsules repeatedly and reproduction capacity was
suggested to be very high. Life span was predicted to be more than 2 years in the tank- cultured
environment. The species was distributed widely
in Asian and Australian waters, and it was
extracted commonly from both wild and cultured
mollusk shells. It is noteworthy to cite that a high
number of these species have been suddenly
observed in suspended cultured oyster shells in
South Korea (Fig. 2b ), which is speculated to be
the result of host oysters being introduced from
different waters (Sekino et al. 2003 ; Sato-Okoshi
et al. 2012 ). In addition to Japan and Australia,
heavy infestation of this species has been reported
on land-based tank-cultured abalone in Chile. It
is also speculated that this infestation was the
result of host abalone being transported from
Japan to Chile accompanying the P. uncinata
population (Radashevsky and Olivares 2005 ).
This species is regarded as one of the most dangerous polydorids, especially in the case of
enclosed aquaculture systems such as abalone
land-based tank culture (Fig. 2c ).
3.3
Polydora haswelli (Fig. 1e )
3.3.1 Morphological Characteristics
Medium- to large-sized worms. Conspicuous
black bands appear on palps and black pigmentation presents on both dorsal and ventral sides of
anterior chaetigers.
3.3.2 Biological and Ecological
Characteristics
Larvae revealed planktotrophic development.
Little is currently known about other characteristics, e.g., life history or reproductive
characteristics. Although the species exhibits
medium sizes in Japan, it reaches larger sizes
and is very common in South Korean mollusk
shells (Fig. 2b ) (Sato-Okoshi et al. 2012 ). The
species causes harmful infestations in many
commercially important shells, but appears
limited to South Korea (Sato-Okoshi et al.
2012 ).
Fig. 2 Pictures of shells infested by Polydora species. ( a )
Inner surface of the left valve of scallop shell showing
heavy infestation by P. brevipalpa after removing the
mantle (From Sato-Okoshi and Abe 2012 ). ( b ) Inner surface of the oyster shell showing heavy infestation by P.
uncinata and P. haswelli (From Sato-Okoshi and Okoshi
2014 ). ( c ) Inner surface of the abalone shell showing
heavy infestation by P. uncinata (From Sato-Okoshi et al.
2012 )
Harmful Shell Borers, Polydora Species (Polychaeta: Spionidae), from Commercially…