Study of Prawn (palaemon)

Study of Prawn (palaemon)- morphology

1. PRAWN (PALAEMON)
DR. B.S. KIRADE
ASSISTANT PROFESSOE
B.S. GOVT. P.G. COLLEGE, JAORA

2. Systematic Position
Phylum-Athropoda
Class-Crustacea
Oreder-Decapoda
Genus -Palamon
Species-Palamonrudis, P.malcolmsonii, p.carcinus, p.lamareii.
Fresh-water prawn., streams, rivers, lakes and ponds in India
free linving, NocturnalOmnivorous(algae,moss,corbonic
mettersetc).
Autotomy= apendasesregenreted

4. External Features-
Shape-Long elongeted, bilaterally symmetrical Strimland shape .
Size-P.malcomsonii 25 to 40 cm, p.lammeri 2.5 to5 cm.
Colour-Pink,whitis, translucent
Body Division –
Two parts of the body-(1) Cephalothorax
(2) Abdomen

5. (1)Cephalothorax-13segments of Head and
Thorex parts fused
•13 seg= ( 5 segmants of Head and 8 segments of thorex).
• One pair Jointed Appendageds present in etach segments.
(2)Abdomen-6 Movebles segments present.
•Last part of body are called telson.
•Swimmwerts/ pleopods present in etach segments.

7. Exoskeleton-
•Cutinius cover ,
•Calcium and sclerotin diposite on body,
•Carapus presents.
•Rostrum process saw like.
•Stalked Eye present in orbit notch.
•Spine present in carpus.

9. External Apertures-
•Mouth
•Anus
•Renal aperture in antenna
•Female reproductive pore-3
rd
paies of walking legs
•Male genital pore –5
th
walking leg’s caxa
•Stetocyst –base on antennule

10. APPENDAGES
Jointed appenadages, aceptAntennulebiramous
Typical app. 2 protopodite= (proximal coxa+ basis.)
Basis = (Exopodite+ Endopodite)
Total 19 Pairs appendages are presnet.
13 pairs app. In cephalothorexregion and
( 13 pairs cephalothorexappendages = 5 cephalic app. + 8 thorecicapp. )
6 pairs app. In cabdominalregion.

12. Antennule
First –Segment’s appendages
One paier
Opening of Statocyt
For Blance, Tectoileand sensce

13. Antenna
II-Segmental app.
One pair
Renal aperture opening
For Blance, Excrationand sensce

14. Mandible Maxillula
III-segmental app
One pair
Strong, califiedFood cutingand
Biet
Exopoditeabst
Mandible
Maxillula

15. Maxilla
Small,
Soft and
liaveslike
Food capturing

16. I-Maxillipede
II-Maxillipede
V-segmental appedages
Repiration
Food capturing
V-segmental appedages
Repiration
Food capturing

17. III-Maxillipede

19. First abdominal
appendage
Second abdominal
appendage
Third abdominal appendag
Fourth abdominal
appendage
Fifth abdominal
appendage
Uropod of Penaeus

22. I. Alimentary canal:
•The alimentary canal is a long tube.
•It starts at the mouth and ends with anus.
•It shows buccal cavity, oesophagus, stomach intestine and rectum.
•The buccal cavity, oesophagus and stomach are lined with euncle.
•It is called stomodaeum or fore-gut. Intestine is lined by endoderm
and is called mesenteron or mid-gut.
The rectum is lined by cuticle and is called the proctodeam or hind gut

23. a) Mouth:
•The mouth is a longitudinal slit on the ventral side of the head.
•It shows labrum on the anterior side.
•Mandibles are lateral.
Thin labium is present on the posterior side
b) Buccal Cavity:
•Mouth leads into the buccal cavity.
•It is short, and vertical. It shows thick and folded cuticle.
•The molar processes of the mandibles project into the
buccal cavity.
The buccal cavity opens into the oesophagus

25. c) Oesophagus:
•It is a short and wide tube.
•It's wall is folded. There are 4 longitudinal folds.
•Each lateral fold is sub-divided by a groove into two smaller
olds.
•The cuticular lining of the oesophagus bears bristles.
•The oesophagus leads into the stomach.

27. d) Stomach:
•It is a large sac.
•It occupies more than half of the cephalothorax region.
•It is divided into large cardiac and small pyloric regions.
i) Cardiac Stomach:
•It is lined with a thin cuticle, h is longitudinally folded. At places the cuticle is thickened and calcified into
plates.
•Near esophageal opening circular plate is present.
•On the roof near anterior end lanceolate plate is present.
•On the floor of cardiac stomach, hastate plate is present.
•Below the hastate plate a pair of comb plates is present. Lateral groove separates the hastate plate and
comb plate.
•Each comb plate has a dense fringe of delicate bristles, which are directed inwards.
•Each lateral groove has a groove plate on the floor.
•Lateral longitudinal folds or guiding ridges are present one on either side of the comb plates.
•The cardio pyloric aperture is X-shaped and is bounded by anterior, posterior and lateral valves.
•The margins of the valves bear setae which act as a sieve. !t permits fluid or very fine food particles to pass
into the pyloric stomach.

28. ii) Pyloric Stomach:
•It lies beneath the posterior part of the cardiac stomach.
•Its lateral walls are thick and project as large longitudinal folds into its lumen.
They divide the pyloric stomach into a small dorsal chamber and a large
ventral chamber.
•The lateral grooves on the sides of the hastate plate open into the ventral
pyloric chamber.
•On the floor of the ventral chamber thick plates are present side by side.
•They are "V" shaped In cross-section. These two plates are called filter plates.
On the ridge of the filter plate a row of bristles can be seen.
•The cuticle of the lateral walls of the ventral pyloric chamber and the filter
plate forms a filter that permits only the fluid to pass through it.
•Behind the filter plate, pair of hepatopancreatic ducts will opens into ventral
pyloric stomach.

31. e)Intestine:It is a long tube extends upto the 6th abdominal segment.
f)Rectum:It is very short. It extends from the 6th abdominal segment
to the anus. Its anterior part is enlarged into a muscular sac'
g)Anus:It is present on the ventral side of the telson.

32. II. Hepatopancreas :
•It is a large orange-red gland.
•It consists to two separate lobes'and develops as a pair of outgrowths.
•The hepatic caecae. from the mid-gut.
•It lies around the stomach.
•It has many branching tubules held together by connective tissue.
•The tubules join to form larger tubes and they unite to form a pair of hepato
pancreatic ducts.
•They open into the ventral pyloric chamber.
•It serves like the liver and pancreas of higher animals.
Functions:
•It secrets digestive enzymes.
•It stores glycogen, fat and calcium like liver.
•It absorbs digested food from intestine.

34. Physiology:
Palaemonis omnivorous. It eats algae, weeds, insect larvae, small fish and debris.
Ingestion:
•Small food particles are caught by the chelate legs and pushed into mouth.
•The 3rd maxillipedes assist the chelate legs in handling large food masses.
•The coxae of the 2nd, maxillipede will hold the food.
•The incisor processes of the mandibles cut the food into small bits.
Digestion:
•Much of the digestion of food takes place in the cardiac stomach.
•It is brought by the digestive juice secreted by the hepatopancreas.
•Dissolved food pass into the lateral grooves and then into the ventral chamber of the pyloric stomach through the
cardio-pyloric aperture.
•Digestion continues in the pyloric stomach.
•The food is filtered through the pyloric filter.
Absorption:
Absorption of food takes place in the hepatopancreas and intestine.
Major part of the digested food passes into the hepatopancreas through the hepatopancreatic ducts.
The un-digested food particles left by the pyloric filter pass into the dorsal pyloric chamber.
Then they go to the intestine.
Egestion: The undigested food is sent out through the anus.

35. Respiratory system
Well developed Aquatic respiration
Orgens-
1.1 -Pair Branchiostegites/ Gill cover
2.3 -Pairs of Epipodites
3.8 -Pairs of Gills

37. 1.1 -Pair Branchiostegites/ Gill cover -
•Thin membrane like verryvascularied
•Samllblood sinus present
•Cotectwith water
•Diffusion of O2 and co2

38. 2. 1 -Pair Epipodite–
•Leavflike str. –presences in Coxaof IIIrt
Maxillipeads
•Highly vascular gills like
3. Gills –
•8 pairs ( 7 pairs visible + 1 paienon visible)
•Three types of Gills-
1. Foot gils-1, coxaof II maxillipeads
2. Arthrobranch-2, III maxillipeads
3. Pleurobranchia–5, walking legs

39. Brachial Formula-
Appendages EpipoditePodobranchiArthrobranchiaPleurobranchiaTotal
I Maxillipead1 - - - 1
II Maxillipead1 1 - - 2
III Maxillipead1 - 2 - 3
I Walking Legs - - - 1 1
II Walking Legs - - - 1 1
III Walking Legs - - - 1 1
IV Walking Legs - - - 1 1
V Walking Legs - - - 1 1
----------------------------------------------------------------------------------------------------------
Total 3 1 2 5 11
Brachial Formula-
Appendages Epipodite Podobranchi Arthrobranchia Pleurobranchia Total
I Maxillipead 1 - - - 1
II Maxillipead 1 1 - - 2
III Maxillipead 1 - 2 - 3
I Walking Legs - - - 1 1
II Walking Legs - - - 1 1
III Walking Legs - - - 1 1
IV Walking Legs - - - 1 1
V Walking Legs - - - 1 1
Total 3 1 2 5 11

40. Blood Vascular System
•Open type
•Lacunar( capillarisabsent, sinus or lacunae and channels present)
Orgens–
1.Pericardium
2.Heart
3.Arteries
4.Blood Sinus/ Lacunnae
5.Blood Channels

41. 1. Blood:
1. It is colorless watery fluid.
2. It contains amoeboid cells.
3. The respiratory pigments is haemocyanin, hence the
blood is bright blue in color when combined with
oxygen. It is colorless when de-oxygenated.
4. Blood distributes digested food, oxygen to all body parts.
5. Blood has the capacity of clotting.

42. 2.Dorsal sinus:
The heart is dorsally placed in the posterior part of thorax. It is
enclosed in a chamber called the dorsal sinus or pericardium. It is
present above the hepato pancreas and the gonad. It shows a thin
septum on the floor. The septum is attached to the dorsal body wall
and to the thoracic wall.

43. 3. Pericardium-
•In dorsal side of thorecisporsion
•In Heamocoelicchamber
•Thin mebrens

44. 4.Heart:
It is a muscular organ. Its apex is directed anteriorly. Broad base is directed
posteriorly.
Cardio-pyloric strand and two lateral strands will keep the heart in position inside
the pericardium. On the wall of heart five pairs of valvular Ostia are present.
Blood from dorsal sinus can enter into the heart through Ostia.
i) First pair of Ostia -Mid dorsal.
ii) Second pair of Ostia -Mid ventral.
iii) The third pair -Posterior.
iv) The fourth pair -Antero laterally,
v) The fifth pair-Postero laterally.

45. Heart –
•Muscular
•Trinacularshape
•Coverdedby pericardium mambrne
•Apex porsionis pointed
•Base brood
•L.s. Cardiopyloricstrand present
•Two lateral strand present
•5-pairs slits / Ostia
•I-Ostia are Doraslside , II-Ostia Ventral,
III-Ostia Post, IV –Ostia Anteriolateral and
V-Ostia are Post-lateral

47. . Arteries-
Four type arteiespresent-
1.Median opthalmicartery
2.Antennary artery
3.Heapaticartery
4.Median posterior artery

48. 1.Median ophathelmic
2. Antennary
3. Hepatopancreatic
4. Median posterior artery
Venrical
thorecic
Venrical
Abdominal
Sternal
Thorecicganglionic
massMandibular
Antennal
Renal
Antennular
Rostral
Optic
Ventral branch
Darsal
branch
Heart
Supra –Intestinal
Ostia

50. . Blood Sinus-Open type, Capillaries and Veins bst, One pair
Long ventral sinus on the base of Hepatopancreas
. BloosChanels–6 Pairs of efferent brachial channels and
Affretnsbrachial channels

51. Heart Pericardial Sinus
Efferent brachial channel
Median longitudinal channels
Marginal Channels
Lateral longitudianl
Channels
Affernetbrachial
Channels
Ventral Sinus
Ventral Blood Lacunnaeof the
HeamocoelalSinus
Arterial branches to viscera and
appendages
Arteries
Course of Circulation in
Gills

52. EXCRETORY SYSTEM
Palaemonexcretory system contains a pair of kidneys called
theantennary or green glandsand a median sac calledrenal sac.
Organs-
1.One pair Antennary / Green glands
2.One pair Lateral ducts
3.Reanl/ Nephroperitonealsac
4.Integument

54. I. Antennary glands:The antennary glands are present in the coxae
of the antennae. Each gland is small, and white in color. Each gland
shows three parts.
1. End -sac.
2. Labyrinth, and
3. Bladder.

55. 1)End -sac :-
•It is small.
•It is the central part of the antennary gland.
•Its wall is folded inside.
•It has ephitheliumand outer connective tissue.
•The cavity of the end-sac contains a large lacuna.
•It opens into the labyrinth by a pore.
2) Labyrinth :
•It is larger than the end sac.
•It is a mass of branched excretory tubules.
•They are held together by connective tissue.
•The labyrinth opens into bladder by several openings.
•The wall of each excretory tubule is formed by excretory epithelium.
3) Bladder :
•Bladder is placed inner side of the end-sac.
•It opens into renal sac by the lateral duct.
•It gives excretory duct or ureter, from its inner side.
•It opens out by the excretory or renal avenue on the inner side of the coxaof the respective
antenna.

56. II. Renal Sac :It is a large median sac present beneath the dorsal
shield. It covers the entire cardiac stomach. Anteriorly it is connected
with the bladder of each antennary gland by a lateral duct.
Working:The green glands perform excretion and osmoregulation.
i)Excretion:The green glands are supplied with blood by the
antennary arteries. By ultrafiltration water and dissolved substances pass
into the end-sacs. The filtrate passes into the labyrinth. By selective
reabsorption the useful products are returned to blood in labyrinth. The
urine is collected and it flows into the bladders. The excretory fluid also
comes here from the renal sac. The urine is passed out through the
ureters and renal apertures.
ii)Osmoregulation:Water enters into the body regularly by osmosis. It
is collected and sent out by green glands. Prawn passes out huge
quantity of water with urine to maintain osmoregulation.

58. NERVOUS SYSTEM
The nervous system of Palaemon resembles that ofannelidas, it
shows
1. Central nervous system.
2. Peripheral nervous system, and
3. Autonomic nervous system.

59. NERVOUS SYSTEM
1.Central N.S.–Brain, 4 circum esophagialcomusers, Ventral ganglionicMass, and Vetral
Nerouscord
1.Brain / Supra-Oesophagialganglion
1. Antennularynerve
2. Optic
3. Opthalmicnerve
4. Antennry
5. Tegumenttal
2.Circum-Oesophagialcommissures-One pair, behind Bairn,connectto sub-oesophagial
ganglion,
3.Ventral-thoracic ganglion mass –Mid cephalothorecic, 11 pairs segsuffed, I-nerve
cephalic,8 pairs thorecicnerves
4.Ventral nerve cord –ventral abdominal nerve cord ,pedAL,Extensor, Flexor
2. Peripheral N.S.
3. Sympathetic N.S.

60. 1.Central nervous system:It includes a pair of cerebral ganglia, a pair of
circumesophageal connectives and a double ventral nerve cord.
i) Cerebral ganglia:
•They lie in front of the junction of the oesophaguswith the cardiac stomach. It is a white bilobed
mass.
•It is also called brain.
ii)Circumoesophagealconnectives:
•These are nerve cords which originate from the postero-lateral parts of the brain, run downwards
round the oesophagusto unite with ventral nerve cord.
•Each connective shows a small commissural ganglion which gives a mandibular nerve to mandible.
iii) Double Ventral nerve cord:
•It lies in the mid-ventral line of the body, it bears seventeen pairs ganglia.
•Tare anterior eleven pairs of ganglia belong to the cephalothorax and are fused to form a single and
large mass called the Cephalothoracic ganglionic mass.
•The posterior six pairs of ganglia of the nerve cord belong to the abdomen and they remain separate.
The sixth and abdominal ganglion is larger than

61. 1. ANTENNULARY NERVE
2. ANTENNARY NERVE
3. BRAIN
4.PERI-OESO PHAGEALL CONNECTIVES
5. SYMPATHETIC NERVOUS SYSTEM
6. VENTRAL THORACIC GANGLIONIC MASS
7. APERTURE FOR STERNAL ARTERY
8. OPTIC NERVE
9. TRANSVERSE CONNECTIVE
10. ABDOMINAL GANGLIA

62. 2.Peripheral nervous system:It contains paired nerves that arise from the central
nervous system to innervate body parts.
a) Nerves from brain:They are 5 pairs.
•Optic,
•Ophthalmic,
•Antennulary,
•Antennary and
•Tegumental nerves.
1.The optic nerves extend outwards and forwards through the eye-stalks and innervate the eyes.
2.Theopthalmic nerves arise close behind the optic nerves. They supply the oscular muscles in the
eye stalks.
3. The Antennulary nerves arise from the brain antero-ventrally. Each nerve enters the antennule
of its side. It also gives the statocystic nerve which goes to the statocyst.
4. The antennary nerves arise from .the ventral side of the brain. Each nerve enters the antenna
of its side.
5. The tegumental nerves arise behind the antennary nerves. They innervate the labrum.

63. b)Nerves from Cephalothoradc ganglionic mass:Eleven pairs
of nerves originate from the cephalo thoracic ganglionic mass.
•A pair of Mandibular nerves to mandible.
•A pair of Maxilhilary nerves to maxillulae.
•A pair of Maxillary nerves to maxillae.
•Three pairs of Maxillipede nerves to maxillipede.
•Five pairs of walking leg nerves to walking legs.
c)Nerves from Abdominal ganglia:
•Three pairs of nerves arise from each abdominal ganglion.
•The fifth abdominal ganglion gives off only two pairs ofnerves.
•The sixth abdominal ganglion gives six pairs of nerves.

66. SENSE ORGENS
1.Compound Eyes-One pair compound
2.Statocysts-Plumesesetae like,ontentecle, app.,whorl
3.Tactile Orgens-plumose setae like, free whorllin pleopodes,
4.OlfectoryOrgens-in longitudinal groove of Outer feeler of
antennule.

67. SENSE ORGANS OF PALAEMON
Palaemon shows different sense organs. They are
•STATOCYSTS,
•TACTILE SETAE,
•OLFACTORY SETAE,
•COMPOUND EYES.
1) STATOCYSTS :
•In palaemon a pair of statocysts can be seen.
•The precoxa of each antennule will contain a statocyst. A statocyst is a round sac.
•It is 1 to 1.5 mm wide. Its outer opening is covered by a small integument. Inside it an oval ring of setae, and heap
of sand grains will be present.
•A receptor setae has two parts 1 )a swollen base and 2) a slender shaft. The base is articulated with the wall of the
sac by a membrane.
•It is supplied with nerve from the statocystic nerve.
•The shaft is bent and fine bristles are present above the bent part.
Working :
•The statocysts are the organs which maintain equilibrium in the normal position. The sand grains lie on the floor of
the statocyst.
•The sand particleswork like statoliths.
•When the position of the animal in water is changed the sand grains press against some of the receptor setae.
•Nerve fibres are stimulated. It is conveyed to the brain. Position is corrected.

71. REPRODUCTIVE SYSTEM
•Male and Female sepret
•Sexual dimorphism
•Male large than Female
•Abdomen small of Male than Female
•Male’s II chelate large than Female
•Female genital opening in coxaof III rd legs
•Male genital opening in 5 thlegs’scaxabase
•In male –appendix masculinaprocess presenein between
andopoditeand Apendixof II pleopod
•Epimeraof abdominal seg. In Female’s Large

73. MALE REPRODUCTIVE SYSTEM
1.Testes -
•2 white and shoft,
•End are fussed and lobe formation ,
•nerrowlong and coiled seminiferoustubules
present eatchtestes.
•Eatchtubules are lyaeredby Germinal
epithelial cells
2.Vasadeferentia-
•Long narrow tublues,
•Opnein seminal vesicale
3.Seminal Vesicle –
• 2 seminal vesicles present and opnein base of
5 thlegs ‘s coxa
• Storgeworke

75. FEMALE REPRODUCTIVE SYSTEM
1.Ovaries -
•2 white and shoft,
•Semicercularand fused both end
•Coverdedby branouscapsule,Eggsarengein
Radial rows
•Yolk more
2.Oviducts-
•Small thin walled tubles,
•Anterior end Funnel likestr.
•Female genital Opening in Coxa‘s base of III
legs

77. History
1.Fertilization -
•May, June and July
•External fertilization
2. Development-
•Tengumantglansare Secreasionsilimymaterial for
attechmentof Egges
•In beery stages formation