mesopc~lagio specicw rilnges bctwcwi I00 and 400 m. Bathypelagic
slirinips It~ck, or rindcrgo a lirnitecl, upward migration.
13. Epj- iLt>(J mesopelitgia shrirrips are grouped according to their
vcrtiorii iiiigrtrtion into five groups. At night the species of the deeper
gt-oiip occul)y to t~ grcvrt, extont the depth horizon vacated by the upwt~rd migrcitioii of the shidlow group. Two groups are recognized
in btttli~~pt~liigic: specics. On the whole, the vertical distribution of
Pcniteitlett is shtdlower than thut, of Ctwidea, and Sergestidlte are most
intimiLtely wsociated with tlir upper layer.
14. l’hc slwinip biomass usrially becomes minirnum between 350
mid 800 r i i itt night. Tli~vio laj,crs ugrcc with a dqjth of fittlnd transition
from tlm lower iii(w)- to btil hyIwletgic species i L t night und from the
half-nd to all-rod speciw by day.
J 6. The dillrnd vertical migrittion of shrimps in rieritic watcm
is modificd to itohieve IendwcLrd transport by means of tidal currents.
1 ti. There iLre t h e types of ontogenetic migrations of the different
groups of‘ sproies. Usually, 1arv;re of pelagic shrimps occur at lesser
depths tli:in the ctdiilt. Hatching of some meso- and bathypelagic species
ttkkes plwe sl)ove their ordinary hitbitationd depth so that the larvae
rise rmcl o w u r in the euphotic: ZOJW or layers immediately adjacent to
it whcrc thrrc is a rirh supply of food, but the juveniles and adolescents
move dcrper. Other spcies are nt’ver, ; k t any stage of their life, present
in surftice or subsurface waters.
17. Srrgestids itre often tLsso(4iLtcd with the sonic scattering layer.
SerrJin Zwen,s rnigrutes verticitlly with a maximum speed of 1 a 8 m/min,
ttnd its swtwtris iq)parently ciLiise i~ sonic scattering layer in Suruga
18. The niorpliological variation of Iiiminescent organs with depth
distribution, and the significmcr of thr: biolumineacencc tire diwuwcd.
‘l’ha xpcvics of the genus A‘rvyoxtvu hilvr tho ability to rotate the orgnnn
of I’estiL 80 tliitt thc. illumination is ~ I ~ \ v ; L ~ s
pointecl tlownward rqprdlrsa of the oricwttition of the iinimid’H hotly.
1 !). The formation of vast ahouls is c.harac*teristic; of filter-fec:dr~s or
potcwtiirl tilter-feedrrs. The function of shoaling by the larvae a n d
juveniles o f ~ ~ l u g i c
slirinips seeiris likely to be to help control their
population ilntl ta niuintiiin p i t i o n within their habitat zone. The size
riud popiiliLtioii cicnsity of the shoals change depending upon the stage
O ~ K I V M t 11. 1’113-spitwning ilggrcption, probably relating to physiological
cllinligcs wit liin t Iic species tht*nisc*lvcs, occurs in Sergia and Acetes.
Thr popiiliLtioii drrrsith of t lie oceanic shrimps in the swarms are
low (mipared with thosc of sornc of the euphausiids. Shoctling is also
niodifird by illumination and temperature.
Htty.
slirinips It~ck, or rindcrgo a lirnitecl, upward migration.
13. Epj- iLt>(J mesopelitgia shrirrips are grouped according to their
vcrtiorii iiiigrtrtion into five groups. At night the species of the deeper
gt-oiip occul)y to t~ grcvrt, extont the depth horizon vacated by the upwt~rd migrcitioii of the shidlow group. Two groups are recognized
in btttli~~pt~liigic: specics. On the whole, the vertical distribution of
Pcniteitlett is shtdlower than thut, of Ctwidea, and Sergestidlte are most
intimiLtely wsociated with tlir upper layer.
14. l’hc slwinip biomass usrially becomes minirnum between 350
mid 800 r i i itt night. Tli~vio laj,crs ugrcc with a dqjth of fittlnd transition
from tlm lower iii(w)- to btil hyIwletgic species i L t night und from the
half-nd to all-rod speciw by day.
J 6. The dillrnd vertical migrittion of shrimps in rieritic watcm
is modificd to itohieve IendwcLrd transport by means of tidal currents.
1 ti. There iLre t h e types of ontogenetic migrations of the different
groups of‘ sproies. Usually, 1arv;re of pelagic shrimps occur at lesser
depths tli:in the ctdiilt. Hatching of some meso- and bathypelagic species
ttkkes plwe sl)ove their ordinary hitbitationd depth so that the larvae
rise rmcl o w u r in the euphotic: ZOJW or layers immediately adjacent to
it whcrc thrrc is a rirh supply of food, but the juveniles and adolescents
move dcrper. Other spcies are nt’ver, ; k t any stage of their life, present
in surftice or subsurface waters.
17. Srrgestids itre often tLsso(4iLtcd with the sonic scattering layer.
SerrJin Zwen,s rnigrutes verticitlly with a maximum speed of 1 a 8 m/min,
ttnd its swtwtris iq)parently ciLiise i~ sonic scattering layer in Suruga
18. The niorpliological variation of Iiiminescent organs with depth
distribution, and the significmcr of thr: biolumineacencc tire diwuwcd.
‘l’ha xpcvics of the genus A‘rvyoxtvu hilvr tho ability to rotate the orgnnn
of I’estiL 80 tliitt thc. illumination is ~ I ~ \ v ; L ~ s
pointecl tlownward rqprdlrsa of the oricwttition of the iinimid’H hotly.
1 !). The formation of vast ahouls is c.harac*teristic; of filter-fec:dr~s or
potcwtiirl tilter-feedrrs. The function of shoaling by the larvae a n d
juveniles o f ~ ~ l u g i c
slirinips seeiris likely to be to help control their
population ilntl ta niuintiiin p i t i o n within their habitat zone. The size
riud popiiliLtioii cicnsity of the shoals change depending upon the stage
O ~ K I V M t 11. 1’113-spitwning ilggrcption, probably relating to physiological
cllinligcs wit liin t Iic species tht*nisc*lvcs, occurs in Sergia and Acetes.
Thr popiiliLtioii drrrsith of t lie oceanic shrimps in the swarms are
low (mipared with thosc of sornc of the euphausiids. Shoctling is also
niodifird by illumination and temperature.
Htty.