actinulan.
/akˈtɪnjᵿlə/, U.S. /ækˈtɪnjələ/ Zoology.
In some hydrozoans: a mobile tentaculate larva, which develops from a planula and transforms into an adult polyp or medusa after dispersal. Also actinula larva.
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the world > animals > invertebrates > subkingdom Metazoa > grade Diploblastica > phylum Coelenterata > [noun] > class Hydrozoa > member of > embryo
planula1835
actinula1871
planulan1886
1871 G. J. Allman Monogr. Gymnoblastic Hydroids i. 92 The remains of the plasma may still throw off portions..which become developed, in a similar way, into free actiniform embryos. To such embryos the name of actinulæ may be given, in order to distinguish them from the planulæ of other hydroids.
1876 A. S. Packard Life Hist. Animals 73 These [septa]..become joined to the external walls of the coral now in the course of formation, forming a groundwork or pedestal on which the actinula rests.
1943 Ecol. Monogr. 13 335/1 The actinula larva of Tubularia appears capable of only very limited active movement.
1958 G. de Beer Embryos & Ancestors (ed. 3) viii. 66 The actinula settles on the bottom and produces the sessile polyp of Tubularia.
2004 E. E. Ruppert et al. Invertebr. Zool. (ed. 7) vii. 162/1 The actinula, which may be creeping or planktonic, is short along the oral–aboral axis and has a whorl of four or more slender tentacles.
This is a new entry (OED Third Edition, November 2010; most recently modified version published online December 2021).
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