floor, probably clout?ly rissociatd with loose detritus on a muddy
bottoni, and their occurrt~iicc in tlic pcliigic community is rather
scarce. Aeuntheph!/rn exirnin Smith. body length up to 180 mm, for
example, is collec!ted not, oii1.v by t h c b bottom trawls but, also by the
traps Rct on the Imttorn (Clarkc, 1 !)72).
In I)ehigic shrimps thv iiitegiimciit is not, rigid duc to poor ctilcnrrous
coiitcnt, particulerly in thcl batlrylwlt~gic species. Pereiopds and
ploopods arc grnorully well rulupt,tv I for swimming. Several adaptations
to pelqic or planktonio existmcc can be seen in the enormously
developed spines and processes on the carapace of protozoeal and
zoeal larvae of the gciiera Ser!/estes and Rergio and the heavily setoee
antcnnule and antonnu of larval stages of fJennadm (see Figs. 13 and
1 L). In t h e genera (Irennadaa, Furwhctlia, Sergestes, Bergia, Acetes and
Peisos antcniial flr~gella of post-larviw rind adults are not, only extremely
long but are: flirther characterized by being divided into proximal and
distal sections ; the difit~al section being heavily setose. These structures
no doubt serve to increase the surface area without, an undue incream
of the volirine or weight. and in this wciy help to retard sinking. Also,
the storage of oil globules or large amounts of lipid in the larvae of such
carids as the genera Pa&p?men, Parapnsiphae, Oplophorua, SystellaapiS
and Hymenodoom reduces the fipecific gravity. Pereiopodal exopoda are
developed in all genera of the Pasiphaeidae and Oplophoridae. Thompson ( I 986) noted that there is a constant reduction in the size of the
exopod of tho pereiopods from pelagic to benthic species within the
member8 of the gcniis Acnntheph?yra. Pelagic carids generally bear
tttt
mandibles cttpablc of both crushing (molar process) and cutting
(incisor process) ('l'hompson. 1966).
Sergestre, Acetee, Lucifer and some speciw of h'ergirr which live in the
epipelagic tind upper mesopelrrgic zones are tranRparent or Hemitmmsparent, with few l t q c orange or red rhromatophorea and largely
colorirless chitin (half-red shrimps), hut ull shrimps inhabiting water
below 500-700 m depth by day htive numerous vmall chromatophores and heavily pigmeiitcrl chitin that varieH from deep-red to
scarlet (all-red shrimps). I'hotophores or modified gastrohepatic
gland tubiiles. which have eithcr betan suspected or have been shown to
be luminous, are observcd in mimy species of the genera such a.8
(?en nadas, Serpvfee, Smgin, l l p r n o d o r n and Parapandalus. Acnnthephyrn is known to produco n luminous secretion. Oplophorus and
Syy~tellaspis posscss hot) h dermal photophores and are capable o€
luminous secretion. The structure of luminescence organs of various
species has bee11 examined bp Kemp (1910a) and Dennell (1940).
bottoni, and their occurrt~iicc in tlic pcliigic community is rather
scarce. Aeuntheph!/rn exirnin Smith. body length up to 180 mm, for
example, is collec!ted not, oii1.v by t h c b bottom trawls but, also by the
traps Rct on the Imttorn (Clarkc, 1 !)72).
In I)ehigic shrimps thv iiitegiimciit is not, rigid duc to poor ctilcnrrous
coiitcnt, particulerly in thcl batlrylwlt~gic species. Pereiopds and
ploopods arc grnorully well rulupt,tv I for swimming. Several adaptations
to pelqic or planktonio existmcc can be seen in the enormously
developed spines and processes on the carapace of protozoeal and
zoeal larvae of the gciiera Ser!/estes and Rergio and the heavily setoee
antcnnule and antonnu of larval stages of fJennadm (see Figs. 13 and
1 L). In t h e genera (Irennadaa, Furwhctlia, Sergestes, Bergia, Acetes and
Peisos antcniial flr~gella of post-larviw rind adults are not, only extremely
long but are: flirther characterized by being divided into proximal and
distal sections ; the difit~al section being heavily setose. These structures
no doubt serve to increase the surface area without, an undue incream
of the volirine or weight. and in this wciy help to retard sinking. Also,
the storage of oil globules or large amounts of lipid in the larvae of such
carids as the genera Pa&p?men, Parapnsiphae, Oplophorua, SystellaapiS
and Hymenodoom reduces the fipecific gravity. Pereiopodal exopoda are
developed in all genera of the Pasiphaeidae and Oplophoridae. Thompson ( I 986) noted that there is a constant reduction in the size of the
exopod of tho pereiopods from pelagic to benthic species within the
member8 of the gcniis Acnntheph?yra. Pelagic carids generally bear
tttt
mandibles cttpablc of both crushing (molar process) and cutting
(incisor process) ('l'hompson. 1966).
Sergestre, Acetee, Lucifer and some speciw of h'ergirr which live in the
epipelagic tind upper mesopelrrgic zones are tranRparent or Hemitmmsparent, with few l t q c orange or red rhromatophorea and largely
colorirless chitin (half-red shrimps), hut ull shrimps inhabiting water
below 500-700 m depth by day htive numerous vmall chromatophores and heavily pigmeiitcrl chitin that varieH from deep-red to
scarlet (all-red shrimps). I'hotophores or modified gastrohepatic
gland tubiiles. which have eithcr betan suspected or have been shown to
be luminous, are observcd in mimy species of the genera such a.8
(?en nadas, Serpvfee, Smgin, l l p r n o d o r n and Parapandalus. Acnnthephyrn is known to produco n luminous secretion. Oplophorus and
Syy~tellaspis posscss hot) h dermal photophores and are capable o€
luminous secretion. The structure of luminescence organs of various
species has bee11 examined bp Kemp (1910a) and Dennell (1940).