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Any of various small, chiefly freshwater flatworms of the order Tricladida, having a soft, broad, ciliated body, a three-branched digestive cavity, and the ability to regenerate body parts.

[From New Latin Plānāria, genus name, from feminine of Late Latin plānārius, on level ground, from plānus, flat; see pelə- in Indo-European roots.]


(Animals) any free-living turbellarian flatworm of the mostly aquatic suborder Tricladida, having a three-branched intestine
[C19: from New Latin Plānāria type genus, from Late Latin plānārius level, flat; see plane1]


(pləˈnɛər i ən)

any of various free-swimming, mostly freshwater flatworms, having an undulating or sluglike motion.
[1885–60; < New Latin Planari(a) a flatworm genus (n. use of feminine of Late Latin plānārius level, on level ground; taken to mean “flat”; see plane1, -ary) + -an1]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.planarian - free-swimming mostly freshwater flatwormsplanarian - free-swimming mostly freshwater flatworms; popular in laboratory studies for the ability to regenerate lost parts
flatworm, platyhelminth - parasitic or free-living worms having a flattened body
class Turbellaria, Turbellaria - free-living flatworms
References in periodicals archive ?
Even amongst planarian flatworms, famous for their ability to regenerate from random tissue fragments, species exist that have completely lost the ability to regenerate.
The study, entitled "zic-1 Expression in Planarian Neoblasts after Injury Controls Anterior Pole Regeneration," was reported in PLOS Genetics.
Jacob, who also won a full four-year scholarship to the University of Massachusetts at Boston, studied the eyespots of planarian (freshwater flatworms) before and after regeneration for his project, Getting NERVEous.
Scientists at the park are monitoring the pink planarian.
The ability to follow individual neoblasts opens the door to uncovering the molecular cues that help planarian stem cells navigate to the site of injury and ultimately may allow scientists to provide therapeutic stem cells with guideposts to their correct destination.
The team, from the University of Nottingham's School of Biology, is studying two types of planarian flatworms that can regenerate muscles, skin, guts and brains through a unique process of cell division.
Levin's group has taken the observation to a new level and has shown that manipulating electrical properties of cells can produce strange results, such as this four-headed planarian worm.
Contributors are actively involved with the development and use of planarian model systems.
Because planarian stem cells share characteristics with those of humans, the work will aid scientists to understand how stem cells can completely repair damaged tissues and organs.
Andy Lavender, Maryville High School, Title: A Study of Planarian Memory.
The first known Texas population of the land planarian Geoplana arkalabamensis Ogren and Darlington, 1991, is reported.
A pluralistic version of utilitarianism may also justify the intuition that, other things being equal, it is better to use a planarian than a mouse, and better to use a rat than a chimpanzee.