Hydra is almost exclusively carnivorous ; its food consisting of small acquatic crutaceans,like watter -flaes, insect larvae and eggs and finger lings of fishes . Hyedra normally hangs attached to any aquatic plant with its tentacles fully extended.This position is advan tegeous for its command considerable amount of hunting teritory.
INGESTION.When a small aquatic organism comes in contact with a tentacle, the nematocysts of the region are immediately discharged, the barbs of the penettrate into it body. The glutinent and the volvwent type of the nematocysts helps tyo retain the prey against the tentacle while the hypno toxin inseceted bny the penetrants gradually para lyses them.The tentacles holding the prey and start contracting and gradually curls towards the mouth .The remaining tentacles also bend towards the prey and all the tentacles combined together contract sop as to c onvey the food into the mouth, which oftewn begin to open before food actually riches it It will thus be seen that it is through the co ordinated action of tedtacles that the prey is catued,paralysed and ultimately conveyed to the mouth.The edges of the irregular mouth gradualy enclose the organism and enforce it into the gastro vascular cavity .The body wall behind the food contracts and forces it down .Frequently organisms , many times the size of the hydras, are succesfuullly ingested .The hypostome beingf very rich in nevous element, is the most sensditive part of the body.Friequently small organisms swim near the tentacles and are allowed to pass . this does not indicate that the nematocysts have failed but that hydra is not at the time in need of food.A well fed hydra doesnot about nor makes exploratory movements with its tentacles; only when it is hungry it is seen that the mere smell of food in its neighbour hood is enough to set the twentacles working but they are not usually puyt in action till the food has been actually touched and , so tosay, smelt.. DIGESTION ;The gastro dermol layer of the hypostome is very rich in secretory cells. The secretion of these cells is poured over the food in swallowing and is a necesary fore runner of the gastric digestion. Immediately after the igestion of food, the secretory cells in the lining of the coelenteron or the gastro vascular cavity ,becomes granuales due to the formation if enzymes. Soon the prey is killed by the alkaline secretion which affect the digestion of the food in the coellentaron.The combined action of the digestion juice and the churning movements , produced by the contraction of the muscles tail of the body wall, is converted the food into small particles .The digestion of food is both intra cellular and extra cellular . It is analogous to that carried out in the stomach and intestines of higher animals like frog and rabbit . Some particles of food within the coelaen teron are engulfed by the amoeboid activity of the free ends of the nutrtive muscular cells is known as intra cellular digestion .Thus in its method of digestion hydra holds an intermediate position betwen the protozoa on the one hand and the higher metazoa on the other .The probable reason for the retention intracellular types of digestion in hydra is that sufficient concentration of the digestive juices cannot be obtain in the coelenteron, which is more or less in free communication with the surrounding water in which hydra lives .Hydra can digests proteins, fats , some carbo hydrates but it doesnot digest starch . EGESTION ; The undigest remains of the food particles like the exoskeleton of the water fleas , are reconveyed to the coelenteron whence they are expelld from the mouth .The structure of the body wall of the hydra is so simplwe that the product of digestion are able to diffuse through the cells , so there is no need for any circulatory system .The digested food generally reaches the rmote part of the body through the membrane and the protoplasm . Thus the coelenteron has the dual function of digestion and circulation.
INGESTION.When a small aquatic organism comes in contact with a tentacle, the nematocysts of the region are immediately discharged, the barbs of the penettrate into it body. The glutinent and the volvwent type of the nematocysts helps tyo retain the prey against the tentacle while the hypno toxin inseceted bny the penetrants gradually para lyses them.The tentacles holding the prey and start contracting and gradually curls towards the mouth .The remaining tentacles also bend towards the prey and all the tentacles combined together contract sop as to c onvey the food into the mouth, which oftewn begin to open before food actually riches it It will thus be seen that it is through the co ordinated action of tedtacles that the prey is catued,paralysed and ultimately conveyed to the mouth.The edges of the irregular mouth gradualy enclose the organism and enforce it into the gastro vascular cavity .The body wall behind the food contracts and forces it down .Frequently organisms , many times the size of the hydras, are succesfuullly ingested .The hypostome beingf very rich in nevous element, is the most sensditive part of the body.Friequently small organisms swim near the tentacles and are allowed to pass . this does not indicate that the nematocysts have failed but that hydra is not at the time in need of food.A well fed hydra doesnot about nor makes exploratory movements with its tentacles; only when it is hungry it is seen that the mere smell of food in its neighbour hood is enough to set the twentacles working but they are not usually puyt in action till the food has been actually touched and , so tosay, smelt.. DIGESTION ;The gastro dermol layer of the hypostome is very rich in secretory cells. The secretion of these cells is poured over the food in swallowing and is a necesary fore runner of the gastric digestion. Immediately after the igestion of food, the secretory cells in the lining of the coelenteron or the gastro vascular cavity ,becomes granuales due to the formation if enzymes. Soon the prey is killed by the alkaline secretion which affect the digestion of the food in the coellentaron.The combined action of the digestion juice and the churning movements , produced by the contraction of the muscles tail of the body wall, is converted the food into small particles .The digestion of food is both intra cellular and extra cellular . It is analogous to that carried out in the stomach and intestines of higher animals like frog and rabbit . Some particles of food within the coelaen teron are engulfed by the amoeboid activity of the free ends of the nutrtive muscular cells is known as intra cellular digestion .Thus in its method of digestion hydra holds an intermediate position betwen the protozoa on the one hand and the higher metazoa on the other .The probable reason for the retention intracellular types of digestion in hydra is that sufficient concentration of the digestive juices cannot be obtain in the coelenteron, which is more or less in free communication with the surrounding water in which hydra lives .Hydra can digests proteins, fats , some carbo hydrates but it doesnot digest starch . EGESTION ; The undigest remains of the food particles like the exoskeleton of the water fleas , are reconveyed to the coelenteron whence they are expelld from the mouth .The structure of the body wall of the hydra is so simplwe that the product of digestion are able to diffuse through the cells , so there is no need for any circulatory system .The digested food generally reaches the rmote part of the body through the membrane and the protoplasm . Thus the coelenteron has the dual function of digestion and circulation.
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