Turbellarian taxonomic database

Abstract / Notes

"The photonegative response was investigated in regenerated brown planaria
(Dugesia tigrina). Old, middle, and young animals were tested, bisected into
heads and tails, and allowed to regenerate. Different regeneration times
affected function, with generally older planaria achieving full functionality
of the photonegative response before younger planaria. Counterintuitively, the
heads of the middle and young lost this function initially (despite only
needing to regenerate their tails) and regained it over time. The size of the
animal was not a factor in the photonegativity response. The biological basis
for the photonegative response is complex, requiring nervous and locomotive
system function and integration. Using the heads from young planaria may serve
as a model in aging, degenerative diseases, or environmental toxins."

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