Firstly, the respects in which they resemble that group to which they are usually thought to be most closely allied, the Coelenterata, must be considered. The best example of this is provided by the genus Cestus (fig.

The tentacle-bases lie one on each side of the throat in such a way that a line drawn from one to the other would intersect at right angles the longer diameter of the flattened throat. It is also often difficult to identify the remains of ctenophores in the guts of possible predators, although the combs sometimes remain intact long enough to provide a clue.

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The outer layer (ectoderm), covering the surface of the body and lining the throat, is cellular in structure.

Body Covering: Epidermis, collenchyme (contains true muscle cells), Support: Hydrostatic "skeleton". Each colloblast (fig.

Which one of the following terms applies to the phylum Ctenophora? 1) All have radial or biradial symmetry.. 2) Good tissue level of organization with very few organs, therefore no true organ systems.. 3) diploblastic (mostly endoderm and ectoderm); some spp.

Digestion is a process involving first the breaking down of the food into particles and secondly the engulfing or ingestion of these particles by individual cells inside which the remaining processes of digestion occur.

…two coelenterate phyla (Cnidaria and Ctenophora) advanced in complexity beyond the parazoans by developing incipient tissues—groups of cells that are integrally coordinated in the performance of a certain function. For instance, they lack the genes and enzymes required to manufacture neurotransmitters like serotonin, dopamine, nitric oxide, octopamine, noradrenaline, and others, otherwise seen in all other animals with a nervous system, with the genes coding for the receptors for each of these neurotransmitters missing.Cydippid ctenophores have bodies that are more or less rounded, sometimes nearly spherical and other times more cylindrical or egg-shaped; the common coastal "sea gooseberry", The tentacles of cydippid ctenophores are typically fringed with tentilla ("little tentacles"), although a few genera have simple tentacles without these sidebranches.

A ctenophore of ordinary shape usually swims mouth for wards and the motion is effected by the rows of combs.

Common Features of two phylum: . The development of the Ctenophora cannot be described here, but it is important to note that the early divisions of the ferti lized egg of a ctenophore are of a different nature from those of a coelenterate egg.

Most lobates are quite passive when moving through the water, using the cilia on their comb rows for propulsion,Adults of most species can regenerate tissues that are damaged or removed,Development of the fertilized eggs is direct; there is no distinctive larval form. Mention must also be made of a small series of aberrant but most interesting genera, the Platyctenea, in which the structure has become more radically modified.

These rows of combs are visible in the living animal as vertical stripes, in which a rippling movement, caused by the motion of succes sive combs, can be detected.

In Coeloplana (fig. Suffice it to say that al though there is strong adherence throughout the greater part of the group to the fundamental principles of the type of structure described in Pleurobrachia, the general form of the body as a whole undergoes startling modification, the various organs and systems being distorted out of all spatial relationship to that state of affairs. Despite their soft, gelatinous bodies, fossils thought to represent ctenophores appear in Among animal phyla, the Ctenophores are more complex than Like sponges and cnidarians, ctenophores have two main layers of cells that sandwich a middle layer of jelly-like material, which is called the Ranging from about 1 millimeter (0.039 in) to 1.5 meters (4.9 ft) in size,For a phylum with relatively few species, ctenophores have a wide range of body plans.The internal cavity forms: a mouth that can usually be closed by muscles; a Little is known about how ctenophores get rid of waste products produced by the cells. The textbook examples are cydippidswith egg-sha… The body is composed of three layers of tissue. Examples: Hormiphora (The Sea Walnut), Pleurobrachia (The Sea gooseberry). Their tentacles (see figure A above) have adhesive structurescalled colloblaststhat do not seem to be homologous to …

Select the phylum that includes coelomate, bilaterian animals that have a structure called a notochord. Each of these canals possesses, in the endoderm lining its outer wall, two concentrations of sex cells—a strip of egg-forming tissue beside a strip of cells which produce spermatozoa.

In this it differs from an anthozoan, which is symmetrical about one plane only if its development be taken into account. Coeloplana adheres to or creeps over the surface of alcyonarian colonies, seaweeds, etc., and although the adult form is so unlike a ctenophore, the larva is much like Pleurobrachia in structure.

Cnidaria and Ctenophora. Space forbids the detailed consideration here of the variations of form exhibited by the Ctenophora.

Animal is a carnivore. However some deeper-living species are strongly pigmented, for example the species known as "Tortugas red"The comb rows of most planktonic ctenophores produce a rainbow effect, which is not caused by In ctenophores, bioluminescence is caused by the activation of calcium-activated proteins named Ctenophores are found in most marine environments: from polar waters to the tropics; near coasts and in mid-ocean; from the surface waters to the ocean depths.Ctenophores may be abundant during the summer months in some coastal locations, but in other places, they are uncommon and difficult to find. For pictures of Ctenophora see Chun, Fauna u. Flora Golf, Neapel, 188o, I.