T1iE liIOIA)(:Y OF t’EI,A(:i(’ SIIRIMPX I N THE OCEAN
289
dectLpotl l;riistthct?iLns und fish i d grind thrtn into small pieces in the
mouthprts; the wall ofthe gut is thin, flexible und s1nootI1, and the gut
cttn contain ii Itirge nniount of foot1 at sny onc time (Oinori, itnpublishcd).
As t1esorit)cd in Scctioii 1 V, t l u w tire severti1 rrports showing that
the populiLtioii maxima of c+oiigeiitbi*icb npeckw tend to occur a t different
depths. A possible interpretation of this phenomenon is given by
‘I’chindo11oviL ( 1 959). Shtl suggests that the phenomenon reduces food
compctition among species which liuvc similttr feeding appendages.
Feedirig of adult Rhrimps rhangcs from a lower trophic level to a
higher oiic with increasing depth of the distribution. A number of
Lucifer pemicillifer Hailsen were orice found in the coastal waters off
Japtin with the hlue-green alga Trichodrsniium thiebautii Oomont ; they
were holding, in many occusions, its colonies near the mouth (Omori,
unpublished). As shown in Table \’I, the species such as Sergestes
windis, Sivyitr IUCC‘IM t ~ n d Pasipham pacifica, inhabiting the lowermost
100 111 ut night,, feed chiefly on herbivorous calanoid copepods and
euphuuniids. Conversely, Acanthephyra purpurea, A. quadrispinosa and
Syslellaspis tlebilis whirl1 live predotninantly below 150 m, take ostracode, d e c t p d s and such mesopelagic fish as Cyclothone spp. in addition
to the copeyods. The shrimps almost certainly catch and swallow
faecal pellets of the epipelihgic aninials before they break up. Diatom
frustules i i i thr gut contents of the lower meso- and bathypelagic
species might be transported through this process. The deeper-living
omnivores tire probably biased towtirds a carnivorous diet because the
particulate niittter avtdablc to them will only be the sinking dead
bodics of orgtiiiisms, casts and
id pellets ~ I U H associated bacteria.
Curnivorous cqwpotfs, ostracwds, medrrstte and chaetognaths are the
main constitueiits of thf* gut wnttsiits of hathypelagic species.
Two procthxsrs of tlir feetling hiLve been observed in the postlarvae of Srr!yiic Iucens in the laboratory (Omori, 19718). When the
shrimp is swiitiining forward, the third maxilliped and the first to third
pereiopodn art‘ usually stretched slightly forward on either side so that,
with the lorig setue at, the fringes, they ran form a scoop-like net as a
cittcliing device.. 111 the first prorrss. 811 A rtemiu nauplius which entered
this d w i w :uid tmic4ied the setae was brought into a position where it
could be seized by the second niaxillipeds. The mandibles then macertbtotl the prey m t i the food pawed to the mouth. Unless physical
contact, with t t i c prey was matlc within this device, the encounter was
unsut~rt~8sfirl. The second proc’ess is an active hunting of living prey.
When t h r shrimp encounturod the prey at a distance of about twice
its body Icy$t,
it suddrnly circ*led around the prey sevcral timcbs so
289
dectLpotl l;riistthct?iLns und fish i d grind thrtn into small pieces in the
mouthprts; the wall ofthe gut is thin, flexible und s1nootI1, and the gut
cttn contain ii Itirge nniount of foot1 at sny onc time (Oinori, itnpublishcd).
As t1esorit)cd in Scctioii 1 V, t l u w tire severti1 rrports showing that
the populiLtioii maxima of c+oiigeiitbi*icb npeckw tend to occur a t different
depths. A possible interpretation of this phenomenon is given by
‘I’chindo11oviL ( 1 959). Shtl suggests that the phenomenon reduces food
compctition among species which liuvc similttr feeding appendages.
Feedirig of adult Rhrimps rhangcs from a lower trophic level to a
higher oiic with increasing depth of the distribution. A number of
Lucifer pemicillifer Hailsen were orice found in the coastal waters off
Japtin with the hlue-green alga Trichodrsniium thiebautii Oomont ; they
were holding, in many occusions, its colonies near the mouth (Omori,
unpublished). As shown in Table \’I, the species such as Sergestes
windis, Sivyitr IUCC‘IM t ~ n d Pasipham pacifica, inhabiting the lowermost
100 111 ut night,, feed chiefly on herbivorous calanoid copepods and
euphuuniids. Conversely, Acanthephyra purpurea, A. quadrispinosa and
Syslellaspis tlebilis whirl1 live predotninantly below 150 m, take ostracode, d e c t p d s and such mesopelagic fish as Cyclothone spp. in addition
to the copeyods. The shrimps almost certainly catch and swallow
faecal pellets of the epipelihgic aninials before they break up. Diatom
frustules i i i thr gut contents of the lower meso- and bathypelagic
species might be transported through this process. The deeper-living
omnivores tire probably biased towtirds a carnivorous diet because the
particulate niittter avtdablc to them will only be the sinking dead
bodics of orgtiiiisms, casts and
id pellets ~ I U H associated bacteria.
Curnivorous cqwpotfs, ostracwds, medrrstte and chaetognaths are the
main constitueiits of thf* gut wnttsiits of hathypelagic species.
Two procthxsrs of tlir feetling hiLve been observed in the postlarvae of Srr!yiic Iucens in the laboratory (Omori, 19718). When the
shrimp is swiitiining forward, the third maxilliped and the first to third
pereiopodn art‘ usually stretched slightly forward on either side so that,
with the lorig setue at, the fringes, they ran form a scoop-like net as a
cittcliing device.. 111 the first prorrss. 811 A rtemiu nauplius which entered
this d w i w :uid tmic4ied the setae was brought into a position where it
could be seized by the second niaxillipeds. The mandibles then macertbtotl the prey m t i the food pawed to the mouth. Unless physical
contact, with t t i c prey was matlc within this device, the encounter was
unsut~rt~8sfirl. The second proc’ess is an active hunting of living prey.
When t h r shrimp encounturod the prey at a distance of about twice
its body Icy$t,
it suddrnly circ*led around the prey sevcral timcbs so