Dugesia

Nama Latin :  Dugesia Tigrina (Planaria maculata)     Phylum :  Platyhelminthes     Sub Phylum :  -     Ordo :  Tricladida     Family :  Dugesiidae     Genus :  -     Species :  Dugesia Tigrina (Planaria maculata)     Kelas :  Turbellaria     Nama Daerah :  -

Pernapasan: Turbellarian energy release appears to be predominantly aerobic, with few peculiarities. It is largely cyanide-sensitive. This indicates that a Warburg-Keilin system is involved in which, after dehydrogenation, hydrogen is transfered by a cytochrome-oxidase system to the final hydrogen acceptor, oxygen. A small cyanide-resistant fraction is probably maintained by iron-free oxidases. No special organs for respiratory exchange or transport occur. The epidermal cilia ventilate the body surface, and undoubtedly improve the rate of absorption. Haemoglobin has been reported from a few rhabdocoels, but is not widely distributed. Available evidence, on the whole, supports the idea that for lack of a more effective system of respiratory requirements of internal cells are a critical limiting factor, favoring small size and a ftattened shape. Habitat: All free-living flatworms are Turbellaria, but some Turbellaria live in or on aquatic hosts. Turbellaria are predominantly marine, although there is a considerable freshwater fauna, and a few live in moist, terrestrial habitats. Pencernaan: The digestive system consists of a mouth, a pharynx lying in a mascular sheath, and an intestine of three main trunks with a large number of small lateral extensions. The muscular pharynx can be extended as a proboscis; this facilitates the capture of food. Digestion is both extracellular and intracellular; 1.e., part of the food is digested in the intestinal trunks by secretions from cells in their walls, whereas other food particles are engulfed by pseudopodia thrust out by cells lining the intestine, and are digested inside of the cells in vacuoles. The degisted food is absorbed by the walls of the intestinal trunks, and because branches from these penetrate all parts of the body, no circulatory system is necessary to carry nutriment from one place to another. As in Hydra, no anus is present, the feces being ejected through the mouth. The food of Dugesia consists largely of small living crustaceans, worms, and dead animals. These are cuptured by the proboscis and ingested after being covered with slime secreted by the slime glands; or the pharynx is attached to the prey, digestive fluid is poured out, and the dissolved particles are pumped into the intestine. Reproduksi: Dugesia typically reproduces asexually by architomy. This is a type of fission is which the worm divides into two fragments without any prior differentiation of new parts. A transverse cleavage just posterior to the pharynx divides the worm into an anterior, nearly normal, worm with head, mouth, pharynxm and most of the gut, and an incomplete, headless posterior mass of tissues which must produce the missing parts. The posterior portion remains immobile until it replaces most of the missing structures whereas the anterior end behaves normally and move about. You are not likely to see fission occurring but it is quite possible that you will see these headless lumps stuck about on the walls of the culture jar if your lab has living specimens.