||Thin white or colored threads
attached at one end to the borders of the mesenteries, as a rule below the
filaments, while the other end is free. They are laden with extraordinarily
numerous nematocysts of various categories. They can be protruded through the
mouth, and in some cases through special pores (cinclides) in the body-wall,
for purposes of defense or paralyses of prey. In histological structure they
differ completely from the mesenterial filaments.
||Thick threads attached to mesenteries below the filaments.
With few nematocysts belonging to some of the same categories as those in the
outgrowths of the body-wall found in some genera of Actiniaria, containing a
strong concentration of nematocysts. They may be simple and spherical,
slightly branched, or even frondose.
||The globular ends of certain tentacles, laden with numerous
nematocysts. They are of different categories in the Corallimorpharia and in
the Actiniaria and seemingly in Madreporaria also.
||Throat, stomodaeum (or gullet, aesophagus, or pharynx); the
tube which leads from the mouth in to the coelenteron.
||The mouth, or upper aperture of the actinopharynx, in the
center of the oral disk.
||In cross section the mesogloeal sphincters of many anemones
are composed of numerous small more of less circular groups of muscle fibers,
these small circles having the appearance of alveoli. In a sphincter in which
the "alveoli" are fairly scattered, the structure may be termed
"alveolar". When the "alveoli" are so close together that
the strands of mesogloea between them are very reduced, and form a network,
the structure may be termed "reticular".
||Small apertures (or organized soft spots which will rupture
readily) in the column through which the acontia, if present, may
||The general cavity of the body of an anemone where digestion,
nutrient absorption, and gas exchange take place.
||A more or less lobed projection from the upper end of a
||The 12 oldest mesenteries originate in a different way from
those which follow in that they arise bilaterally on opposite sides of the
directive axis. Each such "pair" has been called a
"couple". The directives, which normally belong to the 12 primary
mesenteries, are couples as well as pairs.
||Having a body made of two cellular layers only (as opposed to
the majority of animals which are triploblastic), the exterior ectoderm and
the interior endoderm. These two layers are separated by the largely
non-cellular jelly-like mesogloea.
||Muscles which in the main are embedded in the mesogloea.
||The space between two mesenteries belonging to one and the
||Tentacles the cavities of which communicate with endocoels.
||Muscles which in the main are embedded in the mesogloea.
||The lower or internal orifice of the actinopharynx, by which
the cavity of the latter is put into communication with the coelenteron.
||The space between mesenteries belonging to different pairs.
||Tentacles the cavities of which communicate with exocoels.
||A thickened rim running along the free border of a mesentery
from the end of the actinopharynx (in the case of "perfect
mesenteries") downwards. In its lower part the filament is simple, in
its upper part it may be a triple cord. The lateral bands have been called
ciliated tracts (streaks), the median band the cnidoglandular tract (streak)
and this may be very convoluted below the ciliated tracts. In the
Corallimorpharia and Protantheae the filament is always simple, in the
Ptychodactiaria the simple filament is continued distally into a half-funnel
||A circular groove enclosed by a distinct fold, the parapet or
collar, of the column, a little below the tentacles.
||Mesenteries not reaching the actinopharynx.
||The border along which the column joins the pedal disk.Margin
||Vesicles situated on the parapet or in the fosse, which may
have apertures, and are provided with atrichs, basitrichs and
||Large or small apertures in large mesenteries (one aperture
per mesentery), near the margin of the body, by means of which water may pass
through the mesenteries.
||Vesicles situated at the margin, which may possess an
aperture, and containing basitrichs only.
||Infoldings of the endoderm and mesoglea extending from the
body-wall into the gastrovascular cavity, some of which reach the
actinopharynx and divide the gastrovascular cavity. The mesenteries serve to
increase the surface area for digestion and uptake of nutrients.
||The mesenteries are arranged in pairs, each consisting of two
mesenteries adjacent to one another. One can distinguishes between directive
pairs and ordinary pairs. Directives, which are situated in the directive
axis, have their longitudinal muscles (retractors) on their outer sides
turned towards the exocoels.
||One side of each mesentery is occupied by longitudinal
muscles, the other by transverse and parietobasilar muscles; the latter
generally run obliquely from the column to the pedal disc. In most of the
Actiniaria there are also basilar muscles running along both sides of the
base of the mesentery, close to the pedal disc.
||Muscles which in the main are ectodermal, but small parts of
which are embedded in the mesogloea.
||Muscles wholly embedded in the mesogloea.
||Muscles which in the main are endodermal, but a small part of
which is embedded in the mesogloea.
||The mesenteries arising as pairs after the formation of the
12 first mesenteries.
||Special cells in which nematocysts are housed.
||Stinging capsules the thread of which shows several types of
structure. The following categories of nematocysts are present in the
Anthozoa: atrichs: thread without barbs, smooth; holotrichs: thread without a
differentiated basal shaft but with barbs along its whole length; basitrichs:
thread without shaft but with barbs at its base only; microbasic
b-mastigophors: thread with a shaft, but the demarcation between the shaft
and the thread not strongly marked, shaft with barbs; in unexploded capsules
the shaft does not show any funnel-shaped formation.
||Globular strongly ciliated, free swimming bodies with
numerous nematocysts occurring in the coelenteric cavity of Nematostella.
Their true nature is unknown.
||Globular tentacles with numerous basitrichs.
||Spheroid invaginations of the columnar ectoderm into the
mesogloea laden with numerous nematocysts. They occur in Edwardsia and
|Orientation of the body
||A typical animal
belonging to the groups handled here can be divided into two equivalent
halves by a line passing through the endocoels between the directive
mesenteries. This line is the directive axis. In order to describe the
position of the 8 primary mesenteries one uses the arbitrary terms dorsal and
ventral for the two directive couples and dorso-lateral and ventro-lateral
for the lateral ones. The ventral directive couple is the one towards which
theretractors on the four lateral mesenteries face.
||Mesenteries attached to the actinopharynx.
ampullaccous end of certain Athenaria, appears rounded and swollen out into a
||The six oldest tentacles.
||The six oldest pairs of mesenteries.
||The first 12 mesenteries which arise as couples.
||In some taxa the column is externally divisible into regions.
The most proximal zone has been called a physa but this is an ampullaccous
extremity present only in Athenaria. The principal and longest zone of the
column or scapus may be provided with tenaculi or tubercles. Above the
scapus, distally, there is either a thick-walled scapulus or a thin-walled
capitulum. In certain cases both regions are present, the capitulum above the
||Anatomically differentiated smooth grooves running down the
actinopharynx from the mouth to its inner end or beyond this. For the most
part they are connected with directives but not in all cases. In some taxa
the siphonoglyph forms a tube separated from the actinopharynx (in Peachia
mira and Metapeachia).
||The endodermal circular muscles of the column may be
accumulated at or near the margin and form a sphincter which either is
endodermal or embedded in the mesogloea, which is then called a mesogloeal
sphincter. Rarely there is a transition between them, an endo-mesodermal or
meso-endodermal sphincter. The endodermal sphincter shows a different
appearance in cross section.
||More or less solid papillae situated on the column, the
ectoderm of which is partly chitinised and provided with an usually strong,
sometimes stratified cuticle, to which grains of sand or detritus may
||Ampullaccous, non-adhesive evaginations of the column, simple
or compound; with more or less numerous nematocysts of various
||More or less ampullaccous, adhesive evaginations of the
column, simple or more rarely compound, with modified ectoderm, without
nematocysts in their central part. Rarely, as in Sagartia, there is no
evagination, but the ectoderm shows same structure as that of the verrucae
proper and is adhesive (suckers).