Actinian sentence example
- 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.Advertisement
- Duerden has shown that in Porites the ordinary zooids possess only six couples of mesenteries arranged on the Actinian plan.