planula

This term is a specialized biological descriptor used almost exclusively within marine biology and zoology. It describes a specific developmental phase of cnidarians, characterized by a pear-shaped body and a coating of cilia that allow the organism to swim. Because it refers to a precise larval stage, it is rarely used outside of scientific literature or academic contexts.

In a taxonomic context, the planula is the transitional bridge between the pelagic (open water) existence and the benthic (bottom-dwelling) existence. The term emphasizes the motility of the larva before it undergoes the permanent transformation into a sessile polyp.