Sea Anemones belong to the phylum of animals known as the Cnidaria, from the cnida or sting capsule that are present in this major group of animals that also include the corals, jellyfish, hydroids, medusae, and sea fans. Sea anemones, corals and their allies form the class known as the Anthozoa.
Structure and Form
Sea anemones are primitive
consisting mostly of a column with a single opening, the mouth, used to
ingest food and expel wastes. Stinging organelles are found throughout
the animal, in the tentacles, and in some species in stinging threads (acontia),
and beads (acrorhagi).
Tentacles are found in groups of six in many families, with the largest usually on the inside, with increasing numbers near the parapet of the column. The flattish area on top around the mouth is called the disc, or oral disc. The upright column can vary in shape. Wart-like protuberances called verrucae are noticeable in rows on the column in some species. Other anemones possess small suckers, but these need to be observed under a magnifying glass. Anemones are attached to rocks by the basal disc.
Anemone bodies are
divided into two primary layers known as the
ectoderm (or epidermis)
for the exterior, and the internal
endoderm (or gastrodermis) connected
by the mesoglea tissue. The internal gastric centre is also known as the
Beadlet Anemones, Actinia equina, are common on all rocky coasts around Britain.
Sea Anemones often remain in same place for several days, weeks or even months. However they can move around in two ways:
The tentacles manipulate the food to the single opening for digestion. Wastes are expelled through the same opening. Sea anemones breathe through the general body surface. There are no special organs.
to feed difficult sea anemones in aquaria
Biology of Sea Anemones 1991
Series: FUNCTIONAL BIOLOGY SERIES
The first comprehensive treatment of the sea anemones for fifty years, this book presents an integrated synthesis of their biology.
It emphasizes their physiological ecology, evolutionary biology and biological interactions with other taxa, and it includes a wide-ranging bibliography.
424 pages, 87 illus.
Publisher: Chapman and
Hall. Date of publication 1991.
OUT OF PRINT
Book Hunt Page
SEA ANEMONES OF THE ENGLISH CHANNEL (Slide Show)
SEA ANEMONES OF THE WORLD (Daphne Fautin)
IMAGES on flickr
of British Cnidarians
Cnidarians of the World
Actinia equina Common Actinia fragacea Occasional Anemonia viridis Frequent Urticina felina Occasional Metridium senile Frequent Sagartia troglodytes Common Cereus pedunculatus Rare Actinothoe sphyrodeta Rare Sagartiogeton undatus Occasional Anthopleura ballii Rare
Diadumene cincta Offshore, 3 metres depth (Photographs)
All from personal observation (Andy Horton)
From Report in Widewater Lagoon.
Edwardsia ivelli From Report in Widewater Lagoon. (NB. In some reports the grid ref is printed incorrectly).October 1997. A recent search of Widewater Lagoon failed to discover the miniature anemone Edwardsia ivelli.
BMLSS: Home Page
BMLSS: Species List
Cnidaria Web Site (World)