Penaeus japonicus Anatomy PDF

Penaeus japonicas Digestive system  Omnivorous (algae, weeds & small aquatic invertebrates)  Alimentary canal + hepatopancreas  Alimentary canal = fore (stomodeum) , mid (mesentron) , hind gut (proctodaeum)  Both fore and hin...

Penaeus japonicas Digestive system  Omnivorous (algae, weeds & small aquatic invertebrates)  Alimentary canal + hepatopancreas  Alimentary canal = fore (stomodeum) , mid (mesentron) , hind gut (proctodaeum)  Both fore and hind gut have internal lining of cuticle  Hepatopancreas is large, bilobed consisting of numerous tubules composed of cells that secrete enzymes and absorb and store food. Penaeus japonicas Respiratory system  Gills+ eppipodites arise from coxae of maxillipedes (wide gill chamber below the branchiostegite)  Podobranchiae (foot gills), Arthrobranchiae (Joint gills), Pleurobranchiae (side gills) Penaeus japonicas Respiratory system  Course of blood in a gill  Mechanism of respiration  Penaeus japonicas Circulatory System (Heart, Pericardium, arteries, sinuses (blood lacaunae) and blood channels)  Heart is triangular surrounded by the pericardium in the median dorsal part of the thorax. 3 pores of valves called ostia (1dorsal and 2 lateral) allow the blood to enter from surrounding sinuses. Hearts connected to the pericardium by 6 hinges.  Penaeus japonicas Circulatory System  Arteries are 6 (1 ophthalmic, 2 antennary, 2 hepatic, 1 abdominal divides into superior abdominal artery and sternal artery divides into anterior and posterior inferior abdominal arteries)  Sinuses (spaces lying in the midst of the tissues) are pair in number “ventral sinuses” located below the hepatopancreas and thoracic muscles  Blood is carried out from sinuses to gills through afferent branchial channels whilst oxygenated blood carried out to the pericardium through efferent branchial channels  Penaeus japonicas Circulatory System Course of circulation of blood  Blood is carried out from sinuses to gills through afferent branchial channels whilst oxygenated blood carried out to the pericardium through efferent branchial channels  Blood is colourless contains floating amoeboid corpuscles and a respiratory pigment called haemocyanin that composed of copper and protein and turns to blue when oxidised.  Penaeus japonicas Excretory System Antennary “Green –Coxal” glands and integument  Antennary glands situated in the coxa of each antenna  Each gland is opaque and of the size of pea-seed  Each gland consists of end sac, labyrinth “glandular pleux” and bladder  Nitrogenous wastes, waste products, uric acid, ammonia compounds and excess of water from the blood Integument is considered as important excretory organ Penaeus japonicas Nervous System  The nervous system of prawn is similar to that of annelids but with highly specialized sense organs.  Ventral nerve cord and sense organs.  Sense organs include compound eyes, statocyst, Tactile setae and olfactory setae  Penaeus japonicas Sensory organs 1- Compound eyes  There is a pair of black and hemispherical compound eyes that are found in majority of arthropods.  Each eye is borne on a short two-jointed movable stalk lying in an orbital notch.  Each eye is made of a large number, hundreds or thousands, of structural and functional visual units called ommatidia or ocelli lying radially side by side and separated by dark pigment cells.  The eye is covered with a transparent chitinous covering of cuticle forming a cornea.  The cornea is divided into a large number of square facets placed in juxtaposition like squares of a graph paper.  Each facet corresponds to a single ommatidium and below each facet lies one ommatidium inside the eye. Penaeus japonicas Sensory organs 1- Compound eyes Each ommatidium is composed of a number of cells arranged end to end along a central axis and comprises the following structures:  Cornea  The outermost layer  Transparent  Cuticle forming cornea  Divided into a large number of square-like facets that are thickened in the centre to give them the appearance of a biconvex lens.  Each corneal facet behaves like a lens  Sheds off at the time of moulting, again  Secreted by the underlying cells.  Penaeus japonicas Sensory organs 1- Compound eyes  Corneagen cells  A pair of cells under each corneal facet  Modified epidermal cells  Secretes new cornea when it is moulted off  Cone cells or vitrellae  A group of 4 elongated cells  Situated below the corneagen cells  Secrete and surround a transparent and refractile crystalline cone works like a second lens  The inner end of cone cells is long and tapering  Dioptrical region (from cornea to the inner ends of cone-cells) focusing received light by each ommatidium on the inner sensitive part or receptor “retinal region”)  Penaeus japonicas Sensory organs 1- Compound eyes Retinal cells  A group of seven elongated cells  Following the cone cells  Forming the proximal part of the axis of an ommatidium Rhabdome or Optic rod  Elongate and spindle-shaped  Lies beneath the cone cells  Surrounded and secreted and nourished by the retinal cells  Receptor or retinal region (rhabdome and reticular cells) receiving the light rays focused by the dioptrical region.  Penaeus japonicas Sensory organs 1- Compound eyes  Basement membrane  It is the innermost layer of a thin fenestrated or porous membrane that marks the internal boundary of the ommatidia in the compound eye  The ommatidia are innervated by optic nerve fibres, coming from optic ganglia, through the fenestrae orpores in the basement membrane  Pigment sheath  Ommatidia are surrounded by a sheath of dark pigment  Pigments formed by the surrounding amoeboid chromatophores and are arranged in two groups  The retinal pigment surrounding the rhabdome and the iris pigment surrounding the crystalline cone  Pigments exhibit different positions according to the changes in the intensity of light  Penaeus japonicas Sensory organs 1- Compound eyes (Vision)  Each ommatidium produces separate image of a small part of the object seen.  The whole image formed is made of several small pieces produced by adjacanet ommatidia  The vision effected through a compound eye is called mosaic vision  In diurnal crustaceans the compound eyes are adapted for bright light and it produces an apposition or mosaic image  In nocturnal forms, like Prawn, it is adapted for seeing in weak light and superpostion image is formed  Penaeus japonicas Sensory organs Formation apposition or mosaic image  In the bright ,during the day time, light the pigment cells spread in such a way that they completely separate optically one ommatidium from the adjacent ones.  In this condition, rays of light, which strike the cornea indirectly, are absorbed by the pigment cells, therefore, they cannot produce a visual effect.  Only those rays of light, which pass directly through the centre of the cornea, can travel through the ommatidium and reach the rhabdome to form an image of a part of an object.  Penaeus japonicas Sensory organs Formation apposition or mosaic image  These small parts, placed together like the parts in a mosaic, form the image of the entire object. This is known as a mosaic vision and the image is is called an apposition image which is made up of several components placed in juxtaposition.  The sharpness of this image depends upon the number of ommatidia involved and the degree of their isolation from one another ; the larger number of ommatidia and more complete their isolation from one another, the sharper the image.  Eye adapted for this type of image formation functions best at short distances only; it is, therefore, most of the arthropods are short-sighted. Such arthropods are usually night blind, e.g., butterflies.  Penaeus japonicas It is probable that Sensory organs the Prawn like Formation superposition image most of the arthropods can adjust its eyes so as to form both the types of images according to the intensity of light available  In the dim light, at night, the pigment cells migrate towards the distal and basal parts of the ommatidia  In this condition, even the oblique rays of the light are capable of forming a point of image, after passing through a number of ommatidia  As a result, an overlapping of the adjacent points of image takes place and, thus, a continuous image is formed  Such an image is called superposition image  In this case, the vision is not distinct but the animal is able to have some sort of idea of its surrounding objects, specially of their movements  Penaeus japonicas Sensory organs 2-Statocyst  The statocysts are paired organs for maintaining balance  Each statocyst is a nearly spherical cuticular sac about 1·5 mm. in diameter, and is lodged in the coxa of an antennule  It is attached to the lower surface of the concave roof of the coxa and communicates with the exterior by a small opening  Its essential part consists of an oval ring of delicate cuticular setae which are situated in the centre of the sac  Each seta consists of a swollen base and a filamentous shaft, which is bent at the middle of its length  Penaeus japonicas Sensory organs 2-Statocyst  The free ends of the setae point towards the centre of the sac and are covered with fine bristles  Each seta receives at its base a fine branch from the statocystic nerve  There are numerous sand grains within the cavity of the statocyst which are introduced by the animal at the time of moulting  With alteration of position, the sand grains in contact with some of the sensitive setae and the stimulus of contact produces an impulse which is transmitted to the brain  The animal quickly re-orients itself and regains its normal balance  Penaeus japonicas Sensory organs 2-Statocyst  If these organs are are removed the animal appears to lose all sense of balance and fails to perceive the direction of the force of gravity  If freshly molted prawns are kept in an aquarium in which sand grains are replaced by iron filings the animals put fine iron dust within their statocysts.  Such animals when subjected to the influence of a powerful electro-magnet, always swim with their ventral surface turned towards the instrument. This proves that the statocysts are the organs for perceiving the direction of the force of gravity.  Penaeus japonicas Sensory organs 3- Tactile setae  Found on the antennules and antennae “feeler” and rami of pleopods  They are sensory structures concerned with the perception of touch and contact to such as water current and the substratum  Each tactile seta is a cuticular rod the shaft of which consists of two segments: A swollen base, and a plumose distal part tapering at its free end and bearing two rows of barbs 4- Olfactory setae  The olfactory setae are concerned with the perception of smell.  They are found within the rami of the antennule.  Each olfactory seta consists of two segments, but the distal segment is not barbed as in a tactile seta  Penaeus japonicas Reproductive system  The male reproductive organs consist of: (1) A pair of testes (2) A pair of vasa deferentia (3) A pair of seminal vesicles (4) The male gonopores situated at the base of the fifth walking leg  The female reproductive organs consist of: (1) A pair of ovaries (2) A pair of oviducts (3) The female gonopores situated on the inner side of the base of the third walking leg Phylum : Arthropoda Subphylum: Crustacea Class: Malacostraca Example: Panulirus penicillatus (Lobster)  Phylum : Arthropoda Subphylum: Crustacea Class: Malacostraca Example: Penaeus japonicus (Prawn) Neptunus pelagicus (Crab)  Phylum : Arthropoda Subphylum: Crustacea Class: Malacostraca Subclass : Hoplocarida (Mantis shrimp) Example: Squilla mantis ‫تصنيف شعيبة القشريات‬ SubPhylum Crustacea Phylum : Arthropoda Subphylum: Crustacea Class: Branchipoda ‫خيشومية األرجل‬ Example:Daphnia ”Water flea”»‫الدافنيا «برغوث الماء‬ Based on Parthenogenesis environmental Summer –unfertilized eggs - conditions small eggs give female then some males produced to begin sexual reproduction Reproduction Sexual Autumn- fertilized eggs-large- ephippium resist sever conditions- young females appear in spring Sometimes both types of reproduction happen together giving both types of eggs in one season particularly Spring Phylum : Arthropoda Subphylum: Crustacea Class: Branchipoda ‫خيشومية األرجل‬ Example:Daphnia ”Water flea”»‫الدافنيا «برغوث الماء‬ Polymorphism Phylum : Arthropoda Subphylum: Crustacea Class: Branchipoda ‫خيشومية األرجل‬ Example:Artemia ”Brine shrimp Phylum : Arthropoda Subphylum: Crustacea Class: Branchipoda ‫خيشومية األرجل‬ Example:Artemia ”Brine shrimp Phylum : Arthropoda Subphylum: Crustacea Class: Ostracoda Example: Cypris 5 and 2 pairs of appendages on head and thorax no abdominal appendages and ends by caudal styles Reproduction occurs by Parthenogenesis  Subphylum: Crustacea Class: Maxillopoda Subclass: Copepoda Example: Cyclops Some species are parasitic and some are intermediate host of some helminthes Subphylum: Crustacea Class: Maxillopoda Subclass: Cirripedia Examples: Lepas , Balanus & Saculina  Subphylum: Crustacea Class: Maxillopoda Subclass: Cirripedia Examples: Lepas , Balanus & Saculina Subphylum: Crustacea Class: Maxillopoda Subclass: Branchiura Example: Argulus Larval forms of Crustacea A- Nupilus B & D- Protozoaea C- Cypris E-Zoaea F & -G Mysis H & I-Megalopa  Larval forms of Crustacea Alima Phyllosoma Cypris Larval forms of Crustacea and development Crustacea Larval forms and development Prawn Egg Nupilus Protozoaea Zoaea Mysis Adult Crab Egg ( contains Nupilus) Zoaea Megalopa Adult Artemia Egg Nupilus Adult Daphnia Lepas Egg Nupilus Cypris Adult Lobster Egg Phylosoma Adult Squilla Egg Alima Adult Life cycle of crab Importance of Crustacea A- As food B - As fish bait C- As scavengers D- As intermediate hosts E- As pests F- As bioindicators Phylum Arthropoda 2- Subphylum: Uniramia 1- Class: Chilopoda “Centipedes”  Terrestrial  Size 3-25 cm  Respiration takes place by tracheae  Body elongate consists of head and long trunk  Head with a pair of antennae, a pair of of Jaws and 2 pairs of maxillae in addition to eyes (simple or absent)  Trunks is formed of 15- >180 segments fitted with jointed appendages “legs”.  First pair of trunk appendages are modified into poison claws  Genital opening is on the ventral side of the last segment Example: Scolopendra Phylum Arthropoda 2- Subphylum: Uniramia 1- Class: Chilopoda Scolopendra  Terrestrial, carnivorous (insects and worms), nocturnal, greenish centipede  The cuticle lacks the outer waxy layer and calcium salts (hides from direct sun light by day and is active only by night)  Body is elongate dorsoventraly flattened and consists of head and long trunk  Head is:  Formed of 6 fused segments  Covered with cephalic shield carries 2 groups of 4 ocelli  Pair of long multisegmented sensory antennae  Mouth opening is on the ventral side near the borders of the head  Phylum Arthropoda 2- Subphylum: Uniramia 1- Class: Chilopoda Scolopendra  Mouth parts are formed of: 1. the labrum (upper lip) lies anterior to the mouth 2. the mandibles (bears sharp teeth and setae) surrounding the mouth 3. first maxillae (fused together) 4. the second maxillae (partly fused to form the labium (lower lip) 5. the maxillipieds (first pair of trunk appendages directed forwards to lie on the sides of the mouth and end with poison claws bearing at the tips opening of the poison gland) Phylum Arthropoda 2- Subphylum: Uniramia 1- Class: Chilopoda Scolopendra  Trunk is:  Formed of 22 similar segments (first one is fused with the cephalic shield)  Bearing 21 pairs of lateral walking legs (each one is formed of 7 joints: coxa, trochanter, femur, tibia and 3 tarsi end by a claw)  The first pair of legs are modified into poison claws whilst the last pair of legs are much longer and posteriorly directed (anal cerci)  Anus and genital opening are situated on the ventral saide of the last trunk segment  Each segment has dorsal tergum, ventral sternum and 2 lateral pleura  Respiratory stigmata (9 pairs open on the pleura of segments 4,6,9,11,13,15,17,19 and 21) Phylum Arthropoda 2- Subphylum: Uniramia 1- Class: Chilopoda Scolopendra  Most species cause a painful bite to human but not fatal  The bite of a few species may be fatal to young children  Scolopendra is a good mother exhibit maternal care  2- Subphylum: Uniramia 2- Class: Diplopoda “Millipides”  Terrestrial and live in tropical regions  The name “Diplopoda” refers to the presence of 2 pairs of legs  Size 2- >20 cm  Respiration takes place by tracheae  Body elongate consists of head, thorax and multi segmented abdomen.  Head (simple eyes are present or absent, a pair of 7-segmented antennae, jaws, maxillae)  Thorax is 4-segmented (first is legless whilst the others have a single pair of legs)  Abdomen is 100 or more segments, each of which is fitted with two pairs of jointed legs.  The reproductive ducts open on the ventral side of the third segment Example Iulus  Iulus or Julus  Sluggish and secretive worm  Hind in dark and dump places to avoid enemies  Herbivorous animal (few attack roots and produce serious damage in green houses and gardens)  Subclass Chilopoda Class Myriapoda Subclass Diplopoda Similarities  Long slender vermiform body  Large number of segments  Single pair of antennae  Mandibulate mouth parts  Paired jointed appendages  Tracheal respiration  Morphological Differences Chilopoda Diplopoda Body shape Dorsoventrally flattened Cylindrical Body divisions 2 (head and trunk) 3 (head, thorax and abdomen) Segments All are Single Thoracic are single but abdominal are double Antennae long short Maxillae 2 pairs 1 pair 1 pair for each segment 1 pair for thorax but 2 pairs for abdomen No apodal segment First thoracic Legs Arise laterally Arise midventrally First pair modified into poison First pair similar to the others (not claws modified into poison claws) Genital Single and posterior Double and anterior Opisthogoneata Progoneata aperture Spiracles Fewer than the segment As many as the segments Gonopods Not found In males (3rd abdominal segment) Exoskeleton Uncalcified Calcified Differences in Internal Anatomy Chilopoda Diplopoda Stink or odor Not found Present glands Gonads Above the Below the alimentary alimentary canal canal Segments All are Single Thoracic are single but abdominal are double  Differences in Habits Chilopoda Diplopoda Carnivorous Herbivorous Habits Walking fast Walking slow Oviparous or Oviparous viviparous Do not roll into spiral Roll into spiral when when disturbed disturbed