Coelentera Sentence Examples

If the three principal organ-systems of the medusa, namely mouth, tentacles and umbrella, be considered in the light of phylogeny, it is evident that the manubrium bearing the mouth must be the oldest, as representing a common property of all the Coelentera, even of the gastrula embryo of all Enterozoa.

The special property of the medusa is the umbrella, distinguishing the medusa at once from other morphological types among the Coelentera.

Some amongst them (Tergipes, Eolis) are also remarkable for possessing peculiarly modified cells placed in sacs (cnidosacs) at the apices of these same papillae, which resemble the " thread-cells " of the Coelentera.

Polypi (including the Coelentera of later authorities and the Polyzoa).

Of these latter, two grades were further distinguished by Lankester - those which remain possessed of a single archenteric cavity and of two primary cell-layers (the Coelentera or Diploblastica), and those which by nipping off the archenteron give rise to two cavities, the coelom or body-cavity and the metenteron or gut (Coelomata or Triploblastica).

The Metazoa form two main branches; one, Parazoa, is but a small unproductive stock comprising only the Phylum Porifera or Sponges; the other, the great stem of the animal series Enterozoa, gives rise to a large number of diverging Phyla which it is necessary to assign to two levels or grades - a lower, Enterocoela (often called Coelentera), and a higher, Coelomocoela (often called Coelomata).

Enterocoela (see Coelentera).

All Hydrozoa, in the first place, exhibit the three structural features distinctive of the Coelentera.

The structural features which the Mollusca do possess in common with other animals belonging to other great phyla of the animal kingdom are those characteristic of the Coelomata, one of the two great grades (the other and lower being that of the Coelentera) into which the higher animals; or Metazoa as distinguished from the Protozoa, are divided.

In the Coelentera, whatever subsequent changes of shape the little sac may undergo as it grows up to be polyp or jelly-fish, the original arch-enteron remains as the one cavity pervading all regions of the body.

Albinism is restricted to no particular class of the animal kingdom; for partial albinism at least is known to occur in Coelentera, worms, Crustacea, Myriapoda, Coleoptera,Arachnida and fishes.

From the more complex colonial Protozoa the Coelentera are readily separated by their possession of two distinct sets of cells, with diverse functions, arranged in two definite layers, - a condition found in no Protozoan.

The Coelentera, as contrasted with other Metazoa (but not Parazoa), consist of two layers of cells only, an outer layer or ectoderm, an inner layer or endoderm.

In the Coelentera the ectoderm and endoderm are set apart from one another at a very early period in the life-history; generally either by delamination or invagination, processes described in the article Embryology.

The Coelentera may thus be briefly defined as Metazoa which exhibit two embryonic cell-layers only, - the ectoderm and endoderm, - their body-cavities being referable to a single cavity or coelenteron in the endoderm.

This is a type of germ-layer formation never found in the Hydro medusae, though of universal occurrence in all groups of animals above the Coelentera.

The hard calcareous substance to which the name coral is applied is the supporting skeleton of certain members of the Anthozoa, one of the classes of the phylum Coelentera.

We may, with Sedgwick, suppose the coelom to have originated by the enlargement and separation of pouches that pressed outwards from the archenteron into the thickened body-wall (such structures as the genital pouches of some Coelentera, not yet shut off from the rest of the cavity), and they would probably have been four in number and radially disposed about the central cavity.

Linnaeus applied the Latin term Vermes to the modern zoological divisions Mollusca, Coelentera, Protozoa, Tunicata, Echinoderma (qq.v.), as well as to those forms which more modern zoologists have recognized as worms. As a matter of convenience the term Vermes or Vermidea is still employed, for instance in the International Catalogue of Zoological Literature and the Zoological Record, to cover a number of wormlike animals.

Such forms he distinguished as Coelentera, and showed that they had no special affinity with echinoderms, polyzoa, &c. He divided the Coelentera into a group Hydrozoa, in which the sexually produced embryos were usually set free from the surface of the body, and a group Actinozoa, in which the embryos are detached from the interior of the body and escape generally by the oral aperture.

Thus, about 1875, the distinction of Echinoderms from such radiate animals as jelly-fish and corals (see Coelentera), by their possession of a body-cavity ("coelom") distinct from the gut, was fully realized; while their severance from the worms (especially Gephyrea), with which some Echinoderms were long confused, had been necessitated by the recognition in all of a radial symmetry, impressed on the original bilateral symmetry of the larva through the growth of a special division of the coelom, known as the "hydrocoel," and giving rise to a set of water-bearing canals - the watervascular or ambulacral system.