Digestive system of penaeus (prawn)

🦐Digestive system comprises the alimentary canal and a complex digestive gland called hepatopancreas .

🦐Alimentary canal has three divisions, namely stomodaeum or Fore gut,mesodaeum or Mid gut and proctodaeum or hind gut.

 🦐Stomodaeum (fore-gut) consists of mouth, buccal cavity,

Oesophagus and stomach.

🦐Mesodaeum (mesenteron or mid-gut) includes the intestine.

🦐Proctodaeum (hind-gut) consists of the rectum and anus. 

🦐Stomodaeum and proctodaeum

has internal cuticular lining, called intima.

 🦐Mesodaeum has endodermal lining.

🦐Mouth is a longitudinal -slit guarded in front by a chitinous plate, called labrum, on the sides by the mandibles, and behind by the bilobed labium. 

🦐Buccal cavity is a short and compressed chamber.

🦐 Its cuticular lining is irregularly folded.

🦐Running vertically upward from the buccal cavity to the stomach, is the oesophagusts

🦐Stomach is a spacious chamber.

 🦐It fills most of the cephalo-thoracic region.

🦐It has two unequal divisions, large cardiac stomach and small pyloric stomach.

🦐Cardiac stomach mainly serves for the storage and grinding of the food, and the pyloric stomach is mainly concerned

with sorting and straining.

🦐On the floor of the cardiac stomach there are numerous cuticular folds,  armed with setae and spicules. 

🦐Dorso-laterally, its cuticular lining bears numerous stoutand tooth-like denticles.

🦐These serve as an internal masticatory apparatus, often called the gastric mill or gastric armature, for grinding the food.

🦐The cuticular lining of the pyloric

stomach is produced into four longitudinal folds, known as lappets or valvulae. 

🦐One of them is dorso-median, one ventro-median, and the others lateral.

🦐These extend backward to the

mid-gut, incompletely dividing the pyloric chamber into compartments.

 🦐Pyloric stomach has a filtering apparatus, formed of chitinous plates and comb-like bristles.

🦐The proctodaeum is the posterior region of the alimentary canal.

🦐It consists of the hindgut (or rectum) and the anus.

🦐The anus lies at the base of the telson ventrally.

🦐Digestive gland :

The digestive gland consists of a massive hepato-pancreas or liver.

🦐It lies in  the cephalothorasic region. 

🦐The digestive secretions of this gland reach the mesenteron by a pair of openings.

🦐 *Food and feeding:* 

🦐Penaeus feeds on small marine algae, other vegetation, small insects, etc.

🦐The chelate legs collect and pass the food material towards the mouth.

🦐The mandibles cut the food into small pieces.

🦐The maxillae and maxillipeds aid in swallowing the food.