Terminology Description
Terminology Description
Acontia 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.
Acontioids Thick threads attached to mesenteries below the filaments. With few nematocysts belonging to some of the same categories as those in the filaments.
Acrorhagi Marginal 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.
Acrospheres 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.
Actinopharynx Throat, stomodaeum (or gullet, aesophagus, or pharynx); the tube which leads from the mouth in to the coelenteron.
Actinostome The mouth, or upper aperture of the actinopharynx, in the center of the oral disk.
Alveolar 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".
Cinclides Small apertures (or organized soft spots which will rupture readily) in the column through which the acontia, if present, may protrude.
Coelenteron The general cavity of the body of an anemone where digestion, nutrient absorption, and gas exchange take place.
Column Body-wall.
Conchula A more or less lobed projection from the upper end of a siphonoglyph.
Couple 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.
Diploblastic 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.
Ecto-mesogloeal muscles Muscles which in the main are embedded in the mesogloea.
Endocoel The space between two mesenteries belonging to one and the same pair.
Endocoelic tentacles Tentacles the cavities of which communicate with endocoels.
Endo-mesogloeal muscles Muscles which in the main are embedded in the mesogloea.
Enterostome The lower or internal orifice of the actinopharynx, by which the cavity of the latter is put into communication with the coelenteron.
Exocoel The space between mesenteries belonging to different pairs.
Exocoelic tentacles Tentacles the cavities of which communicate with exocoels.
Filament 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 formation.
Fosse A circular groove enclosed by a distinct fold, the parapet or collar, of the column, a little below the tentacles.
Imperfect mesenteries Mesenteries not reaching the actinopharynx.
Limbus The border along which the column joins the pedal disk.Margin
Marginal spherules Vesicles situated on the parapet or in the fosse, which may have apertures, and are provided with atrichs, basitrichs and spirocysts.
Marginal stomata 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.
Marginal pseudospherules Vesicles situated at the margin, which may possess an aperture, and containing basitrichs only.
Mesenteries 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.
Mesenterial arrangement 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.
Mesenterial muscles 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.
Meso-ectodermal muscles Muscles which in the main are ectodermal, but small parts of which are embedded in the mesogloea.
Mesogloeal muscles Muscles wholly embedded in the mesogloea.
Meso-endodermal muscles Muscles which in the main are endodermal, but a small part of which is embedded in the mesogloea.
Metacnemes The mesenteries arising as pairs after the formation of the 12 first mesenteries.
Nematoblasts Special cells in which nematocysts are housed.
Nematocysts 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.
Nematosomes Globular strongly ciliated, free swimming bodies with numerous nematocysts occurring in the coelenteric cavity of Nematostella. Their true nature is unknown.
Nematospheres Globular tentacles with numerous basitrichs.
Nemathybomes Spheroid invaginations of the columnar ectoderm into the mesogloea laden with numerous nematocysts. They occur in Edwardsia and Isoedwardsia.
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.
Perfect mesenteries Mesenteries attached to the actinopharynx.
Physa The aboral ampullaccous end of certain Athenaria, appears rounded and swollen out into a bladder-like structure.
Primary tentacles The six oldest tentacles.
Primary mesenteries The six oldest pairs of mesenteries.
Protocnemes The first 12 mesenteries which arise as couples.
Scapus 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 scapulus.
Siphonoglyphs 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).
Sphincter 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.
Tenaculi 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 adhere.
Vesicles Ampullaccous, non-adhesive evaginations of the column, simple or compound; with more or less numerous nematocysts of various categories.
Verrucae 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).