THE I310IAO(?Y OF J’EI,AQT(‘ SHRlMP8 I N THE OCEAN
311
20, The spitwning bc.haviour of shrimps is describcd. The lower
rncso- and bittliypelagi(* spccics produce larger but fewer eggs and
lnrviw rthtivc to the epipcltigic s p c i c s . In tiny one species a big
fcmitlc H ~ ~ W I ~ X
a grtvikr nrimbcr of c g g ~ than H smctll. femnle. Thus tho
numbcr of eggs prodriocd by i t Rhrimp is dependant not only upon the
sizes of tlir egg but also upon 1 hr volume of the parent.
31. ‘t’lie spnwning of epi- arid mesopelagic sergestids is usually
hrnviest driring suninic’r in 1 emperate regions. That of the carids
takes plitctx in spring and autumn. Apparently the spawning of shallowliving pcnaeitls and sergestids in the temperate regions is related to
temperttture. whcress it seems to be related to wind direction of monsootis and precipitation in the tropicti1 region. Probably spawning of
lowrr mew- iind bathypelagic carids occurs during much of the year.
22. IJndcr normal condition, pelagic shrimps grow to maturity
passing through the following developmcntal stagect. The number in
pmwithrsis means the number of instnrs.
(?enrtcidas: n;aiipliuH ( !)-protozoea (3)-zoea (4)-post-larva
Srr!pyteAq cind Nerqia: nuupliua (2)-protozoea (3)-zoea (2)-postt-larva
Pp/nZidiurri : nt~riplius ( !)-protozoea (3)-zoea (I)-post-larva
Acetes: nnuplius (3)-protozoetL (3)-zoetl ( I )-post-larva
I,~ir.ifev: n i ~ u
pl iiis (2)-prot,ozoeu (3)-zoca (2)-post-larva
I’asiphu~n iand I’crrrcpmiphp: zoc”~ (4)-post-larva
Oplophor us, 1!ym c> nohra and S,tjelelk(ispis : zoea (6)-post-l ttrva
..3cwrrth~ph,tjrn: zo(vi (7 or rnorc)-post-larva
23. ‘l‘he criticttl period of 8erqia lwens exists soon aftcr it begins
to feed on phytoplankton in the protozoeal stages. The highest mortality
during its life history is in the larval stages. The greatest factor
affecting flwtiiiitions in abundance of 8. lucens appears to be the
tttwiprwitiirc driring the breeding season.
24. The lifc-span of the species in the genera Gennadm, SergestPs
and Sergia in epi- and mesopelagic zones is considered to be one or
two years. Them are two tlypes of generations in dcetes japonicus: the
longcvity of ttir short-term gcmerution is less than three months.
whereas thirt of t h o long-term generation is nine to ten months. Probably the species of Oplophorw A cunfhephyra and Systellaclpicl attain
sexual maturity in t3he Becond, but mostly in the third, year of their
lives. and produce a sequence of hood8 within the next one or two
years. l ’ h ~ longevity of such hithypelagic shrimps as Hymenodora is
ttssumcd to 111) to 5- H years.
25. Epipelugic and upper mesopelagic shrimps feed on living prey
and decomposing dead material which are moRt common at the time
311
20, The spitwning bc.haviour of shrimps is describcd. The lower
rncso- and bittliypelagi(* spccics produce larger but fewer eggs and
lnrviw rthtivc to the epipcltigic s p c i c s . In tiny one species a big
fcmitlc H ~ ~ W I ~ X
a grtvikr nrimbcr of c g g ~ than H smctll. femnle. Thus tho
numbcr of eggs prodriocd by i t Rhrimp is dependant not only upon the
sizes of tlir egg but also upon 1 hr volume of the parent.
31. ‘t’lie spnwning of epi- arid mesopelagic sergestids is usually
hrnviest driring suninic’r in 1 emperate regions. That of the carids
takes plitctx in spring and autumn. Apparently the spawning of shallowliving pcnaeitls and sergestids in the temperate regions is related to
temperttture. whcress it seems to be related to wind direction of monsootis and precipitation in the tropicti1 region. Probably spawning of
lowrr mew- iind bathypelagic carids occurs during much of the year.
22. IJndcr normal condition, pelagic shrimps grow to maturity
passing through the following developmcntal stagect. The number in
pmwithrsis means the number of instnrs.
(?enrtcidas: n;aiipliuH ( !)-protozoea (3)-zoea (4)-post-larva
Srr!pyteAq cind Nerqia: nuupliua (2)-protozoea (3)-zoea (2)-postt-larva
Pp/nZidiurri : nt~riplius ( !)-protozoea (3)-zoea (I)-post-larva
Acetes: nnuplius (3)-protozoetL (3)-zoetl ( I )-post-larva
I,~ir.ifev: n i ~ u
pl iiis (2)-prot,ozoeu (3)-zoca (2)-post-larva
I’asiphu~n iand I’crrrcpmiphp: zoc”~ (4)-post-larva
Oplophor us, 1!ym c> nohra and S,tjelelk(ispis : zoea (6)-post-l ttrva
..3cwrrth~ph,tjrn: zo(vi (7 or rnorc)-post-larva
23. ‘l‘he criticttl period of 8erqia lwens exists soon aftcr it begins
to feed on phytoplankton in the protozoeal stages. The highest mortality
during its life history is in the larval stages. The greatest factor
affecting flwtiiiitions in abundance of 8. lucens appears to be the
tttwiprwitiirc driring the breeding season.
24. The lifc-span of the species in the genera Gennadm, SergestPs
and Sergia in epi- and mesopelagic zones is considered to be one or
two years. Them are two tlypes of generations in dcetes japonicus: the
longcvity of ttir short-term gcmerution is less than three months.
whereas thirt of t h o long-term generation is nine to ten months. Probably the species of Oplophorw A cunfhephyra and Systellaclpicl attain
sexual maturity in t3he Becond, but mostly in the third, year of their
lives. and produce a sequence of hood8 within the next one or two
years. l ’ h ~ longevity of such hithypelagic shrimps as Hymenodora is
ttssumcd to 111) to 5- H years.
25. Epipelugic and upper mesopelagic shrimps feed on living prey
and decomposing dead material which are moRt common at the time