Definition of planula in English:


nounPlural planulae

  • A free-swimming coelenterate larva with a flattened, ciliated, solid body.

    as modifier ‘a planula larva’
    • ‘The planulae of most cnidarians attach and lose, at most, a coat of swimming cilia.’
    • ‘The planula larva has very few apoptotic cells.’
    • ‘The planula larva settles on a hermit crab shell and metamorphoses into a primary polyp.’
    • ‘Fertilized eggs may be brooded for a time or may develop directly into a free-swimming, ciliated planula larva.’
    • ‘Hydra lives in freshwater, lacks a ciliated planula, and has clearly lost a medusa stage during its ancestry.’


Late 19th century: modern Latin, diminutive of Latin planus ‘plane, flat’.