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The organism itself does not have to be completely cut into separate pieces for the regeneration phenomenon to be witnessed. In fact, if the head of a planarian is cut in half down its center, and each side retained on the organism, it is possible for the planarian to regenerate two heads and continue to live. [35]
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 ]
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]
The food of P. torva consists of freshwater gastropods, tubificid worms, and freshwater arthropods, such as isopods of the genus Asellus and chironomid larvae, although it shows a clear preference for snails. [3] In the United Kingdom, P. torva is a successful predator of the invasive New Zealand mud snail (Potamopyrgus jenkinsi). [4]
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 complete mitogenome of Caenoplana coerulea is 18,621 bp in length. [7] Its main characteristic is a cytochrome c oxidase subunit 2 gene of unusual length, with a cox2 encoded protein 505 aa in length (compared to about 250 aa in other geoplanids); this characteristic of a very long cox2 is also found in other members of the subfamily Rhynchodeminae, to which Caenoplana coerulea belongs.
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.
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.