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A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species and also in some species of Ctenophores. Some groups of Nemerteans also produce larvae that are very similar to the planula.
Depending on the species, the planula either metamorphoses directly into a free-swimming, miniature version of the mobile adult form, or navigates through the water until it reaches a hard substrate (many may prefer specific substrates) where it anchors and grows into a polyp. The miniature-adult types include many open-ocean scyphozoans. The attaching types include all anthozoans with a planula stage, many coastal scyphozoans, and some hydrozoans.
Feeding and locomotion
- Ruppert EE, Fox RS, Barnes RD (2004). "Nemertea". Invertebrate Zoology (7 ed.). Brooks / Cole. pp. 271–274. ISBN 0-03-025982-7.
- Nakanishi, Nagayasu; Yuan, David; Jacobs, David K.; Hartenstein, Volker (2008). "Early development, pattern, and reorganization of the planula nervous system in Aurelia (Cnidaria, Scyphozoa)". Development Genes and Evolution. 218 (10): 511–524. doi:10.1007/s00427-008-0239-7.