New Latin Actīniagenus namefrom Greek aktīsaktīn-rayactino–
American Heritage Dictionary of the English Language, 5th Edition
Actinian Sentence Examples
3) has very constant anatomical characters, differing in some important respects from the Actinian zooid, which has been taken as a type.
2.-I, Portion of epithelium from the tentacle of an Actinian, showing three supporting cells and one sense cell (sc); 2, a cnidoblast with enclosed nematocyst from the same specimen; 3 and 4, two forms of gland cell from the stomodaeum; 5a, 5b, epithelio-muscular cells from the tentacle in different states of contraction; 5c, an epithelio-muscular cell from the endoderm, containing a symbiotic zooxanthella; 6, a ganglion cell from the ectoderm of the peristome.
-A, Diagram showing the sequence of mesenterial development in an Actinian.
A pause in the development follows, during which no new mesenteries are formed, and then the six-rayed symmetry characteristic of a normal Actinian zooid is completed by the formation of the mesenteries V, V in the lateral chambers, and VI, VI in the sulcolateral chambers, their muscle-banners being so disposed that they form couples respectively with II, II and I, I.
Moreover, there are some modern corals in which the secondary cycle of mesenteries departs from the Actinian plan.