planarian

[ pluh-nair-ee-uhn ]

noun

, Zoology.

1. any of various free-swimming, mostly freshwater flatworms of the class Turbellaria, having an undulating or sluglike motion: popular in laboratory studies for the ability to regenerate lost parts.

planarian

/ pləˈnɛərɪən /

noun

1. any free-living turbellarian flatworm of the mostly aquatic suborder Tricladida, having a three-branched intestine

planarian

/ plə-nâr′ē-ən /

1. Any of various small, chiefly freshwater flatworms of the class Turbellaria, having soft, broad, ciliated bodies shaped like a leaf. Planarians have a mouth on their lower side that is often closer to the tail than the head, and a three-branched digestive cavity. If a planarian is cut into several pieces, each piece can grow into a whole new organism.

Word History and Origins

Origin of planarian¹

1885–60; < New Latin Planari ( a ) a flatworm genus (noun use of feminine of Late Latin plānārius level, on level ground; taken to mean “flat”; plane ¹, -ary + -an

Word History and Origins

Origin of planarian¹

C19: from New Latin Plānāria type genus, from Late Latin plānārius level, flat; see plane ¹

Example Sentences

Sikes has been working with acoels for about 20 years, and their symbiotic relationship differentiates them from other animals that regenerate, like planarian flatworms and axolotls.

From Science Daily

Solana and his group had previously focused on stem cells in a different type of worm: the planarian, or flatworm.

From Science Daily

Cut a chunk out of a planarian, and it will regrow exactly those tissues that were removed, neither more nor less.

From Scientific American

The research suggests that cellular guides hidden throughout the planarian body may make it possible for the worm’s newly grown neurons to retrace their steps.

From New York Times

It has been suggested7 that planarian fission is regulated by gradients in metabolic activity, molecular positional cues or neurohormone molecules along the anterior–posterior body axis.

From Nature