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The planarian has a soft, flat, wedge-shaped body that may be black, brown, blue, gray, or white. The blunt, triangular head has two ocelli (eyespots), pigmented areas that are sensitive to light. There are two auricles (earlike projections) at the base of the head, which are sensitive to touch and the presence of certain chemicals.
Planaria is a genus of planarians in the family Planariidae. Due to its excellent ability to regenerate, species of Planaria has also been used as model organisms in regeneration studies. [ 1 ] When an individual is cut into pieces, each piece has the ability to regenerate into a fully formed individual. [ 2 ]
Morgan found that a piece corresponding to 1/279th of a planarian [11] or a fragment with as few as 10,000 cells could regenerate into a new worm within one to two weeks. [13] Morgan also found that if both the head and the tail were cut off a flatworm the middle segment would regenerate a head from the former anterior end and a tail from the ...
The head usually has a somewhat triangular shape and has two eyes (except for some subterranean eyeless species). The main differences between Dugesiidae and other freshwater planarians are related to the anatomy of the eyes and the copulatory apparatus.
Epimorphosis is defined as the regeneration of a specific part of an organism in a way that involves extensive cell proliferation of somatic stem cells, [1] dedifferentiation, and reformation, [2] as well as blastema formation. [3]
Dugesia species have an elongated body with a slightly triangle-shaped head. Usually they have grey, brown or black colors on the dorsal body surface, the ventral surface uses to be paler. These animals have a couple of eyes constituted by a multicellular pigmented cup with many retinal cells to detect the amount of light in the nearby environment.
Bipalium species are predatory.Some species prey on earthworms, while others may also feed on mollusks. [10] [11] These flatworms can track their prey. [12]When captured, earthworms begin to react to the attack, but the flatworm uses the muscles in its body, as well as sticky secretions, to attach itself to the earthworm to prevent escape.
The headless fragment must regenerate a completely new head. In 'paratomy', the split occurs perpendicular to the antero-posterior axis and the split is preceded by the "pregeneration" of the anterior structures in the posterior portion. The two organisms have their body axis aligned i.e. they develop in a head to tail fashion.