TIIE IIIOLOUY OF PELAGIC SHRIMPS I N THE O(‘EAN
29.3
several phytoplankton species and Artewiia nauplii as food. The
following are some of results obtained by his experiments. The mean
feeding rate of the protozoeal-zoeal stages on DunaEiella tertiolecta
Butcher was 805 cells/individual/h and the mean assimilation was
10.1 % of calories ingested. The feeding rate of adult was 4 850 cells/
individual/h with an assimilation of 7.7:/,. Individual adult Lucifer
ingested about 42 Artcmia nnuplii pvr tliiv ; the mcan assimilation was
22% of Artemk calorirs ingrstrtl. Tho mean grow and net growth
efficiencies of c:omhincd stagcs w(w I O.Z(%, nntl X I 1 % respectively.
On the other hiitltl, curly r)o~tt-l;lt.\~ill st;Lg(:s of Spryia ZUC~VM inge8totl
I!) to 7 0 Artemia nthuplii, al)l)roxirri;bt,cily I :j 45%, of its own wctight,
per day (average I9 pg C/day), cintl gibilltd tho weight of 1 O. I [ ~ g
(:/day
under laboratory conditions. A nrrrnbcr of adult specimens having
their foreguts full of incompletely fragmented prey were kept in filtered
seawater for observation of the digestive processes. The shrimps always
retained the gut content,s €or 6 to 8 hours until defaecation (Omori,
unpublished).
13. l’rerlators
Species of the genera d c e f e s and Lucifer must play a significant
role as the food of fish and shrimps in the coastal waters. Although
very little is known about the feeding habits of the post-larvae and
juveniles of economically important fishes, the shrimps are no doubt the
dominant components of their food in their nursery regions. Acetes and
Lucifer are extremely important in the food web of the fauna of
mangrove swamps in the Indo-west-Pacific.
Hardenburg (1931) mentioned that all fish stomachs rxamined by
him a t the mouth of Rokan River, Sumatra, wwc f i l l ~ l with ,Sar:/a4te.u
spp. As he reported that those ,Ser!/wfp.y w ( w fishcd c:omrricwiiilly in
the area, no doubt they are Acetm spp. A c P ~ P . ~
r?r?ylhlrwu.9, A . sa.rrulr~tux
Krrayer and d. vulguris Hanscn arc t h o main food itoms of vitrious
coastal fishes of the Singapore Straits such as the anchovy IJn,!/rauli.y
dussumieri (Valenciennes), the silverside dtharina valenciennai (Hleekcr)
and the lizardfish Sauridu gracilis (Quoy et Gaimard) during the
period from December to March (Tham, 1950). OfTqhore in the 8outh
China Sea Acetes are eaten by the mackerel ,%ombar sp. and the cephalopod Loligo sp. The local fishermen often locate the fishing ground of
Loligo by the shoals of Acetes a t night (A. K . Tham, personal communication).
According to Nataraj ( 1 ‘347) ,4c~tas arythraeus and A . serrulatus
johni appear in large swarms in the coastal waters of south India from
April to July and during these months are invariably found in the
29.3
several phytoplankton species and Artewiia nauplii as food. The
following are some of results obtained by his experiments. The mean
feeding rate of the protozoeal-zoeal stages on DunaEiella tertiolecta
Butcher was 805 cells/individual/h and the mean assimilation was
10.1 % of calories ingested. The feeding rate of adult was 4 850 cells/
individual/h with an assimilation of 7.7:/,. Individual adult Lucifer
ingested about 42 Artcmia nnuplii pvr tliiv ; the mcan assimilation was
22% of Artemk calorirs ingrstrtl. Tho mean grow and net growth
efficiencies of c:omhincd stagcs w(w I O.Z(%, nntl X I 1 % respectively.
On the other hiitltl, curly r)o~tt-l;lt.\~ill st;Lg(:s of Spryia ZUC~VM inge8totl
I!) to 7 0 Artemia nthuplii, al)l)roxirri;bt,cily I :j 45%, of its own wctight,
per day (average I9 pg C/day), cintl gibilltd tho weight of 1 O. I [ ~ g
(:/day
under laboratory conditions. A nrrrnbcr of adult specimens having
their foreguts full of incompletely fragmented prey were kept in filtered
seawater for observation of the digestive processes. The shrimps always
retained the gut content,s €or 6 to 8 hours until defaecation (Omori,
unpublished).
13. l’rerlators
Species of the genera d c e f e s and Lucifer must play a significant
role as the food of fish and shrimps in the coastal waters. Although
very little is known about the feeding habits of the post-larvae and
juveniles of economically important fishes, the shrimps are no doubt the
dominant components of their food in their nursery regions. Acetes and
Lucifer are extremely important in the food web of the fauna of
mangrove swamps in the Indo-west-Pacific.
Hardenburg (1931) mentioned that all fish stomachs rxamined by
him a t the mouth of Rokan River, Sumatra, wwc f i l l ~ l with ,Sar:/a4te.u
spp. As he reported that those ,Ser!/wfp.y w ( w fishcd c:omrricwiiilly in
the area, no doubt they are Acetm spp. A c P ~ P . ~
r?r?ylhlrwu.9, A . sa.rrulr~tux
Krrayer and d. vulguris Hanscn arc t h o main food itoms of vitrious
coastal fishes of the Singapore Straits such as the anchovy IJn,!/rauli.y
dussumieri (Valenciennes), the silverside dtharina valenciennai (Hleekcr)
and the lizardfish Sauridu gracilis (Quoy et Gaimard) during the
period from December to March (Tham, 1950). OfTqhore in the 8outh
China Sea Acetes are eaten by the mackerel ,%ombar sp. and the cephalopod Loligo sp. The local fishermen often locate the fishing ground of
Loligo by the shoals of Acetes a t night (A. K . Tham, personal communication).
According to Nataraj ( 1 ‘347) ,4c~tas arythraeus and A . serrulatus
johni appear in large swarms in the coastal waters of south India from
April to July and during these months are invariably found in the