Spirularia is an
order of marine
Cnidaria
Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter.
Their distinguishing feature is cnidocytes, specialized cells that ...
ns, tube-dwelling anemones, in the
subclass Ceriantharia
Tube-dwelling anemones or ceriantharians look very similar to sea anemones but belong to an entirely different class of anthozoans. They are solitary, living buried in soft sediments. Tube anemones live inside and can withdraw into tubes, which ...
.
It is one of the two orders making up Ceriantharia and includes two families,
Botrucnidiferidae
and
Cerianthidae
Cerianthidae is a family of tube-dwelling anemones in the order Spirularia of the subclass Ceriantharia.
Genera
The World Register of Marine Species includes the following genera in the family:
* ''Anthoactis'' Leloup, 1932
* ''Apiactis'' Bene ...
, and around 99 species. The two orders differ in the makeup of their cnidome (the types of
cnidocyte
A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this c ...
present), the relative sizes of the oral discs and the shape and structure of the mesenteries.
These anemones dwell in parchment-like tubes immersed in soft sediment, and have two whorls of tentacles, the outer tentacles being much longer than the inner ones.
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References
Ceriantharia
Cnidarian orders
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