Many freshwater and marine sponges disintegrate in adverse circumstances. The body of sponges is perforated by numerous minute pores and they possess a unique system of canals in their body; all these are never found in Metazoa.
The size varies from few mm to massive having 1 or 2 metres diameter. 4. Spicules are differentiated into megascleres and microscleres. The wall thickens and gets folded to form canals, perforations form ostia and osculum. In calcareous sponges, the leuconoid structure may be attained by way of asconoid and syconoid stages. At first these radial canals are free projections and the outside water surrounds their whole length, for there are no definite incurrent channels. 1.
The nature of sponges was debated until well into the nineteenth century, although evidence of their animal nature was given in 1765 by who saw the water currents and movements of the oscula.
The mesenchyme contains skeletal spicules and several types of amoebocytes, all embedded in a gelatinous matrix.
Ecosystems. The course of water current is dermal ostia → incurrent canals → prosodus (if present) → prosopyles → flagellated chambers → apopyles → aphodus (if present) → excurrent canals → larger channels → oscula → out. 5. According to Hyman, the important features of the asconoid structure are the simple wall and the complete continuous lining epithelium of choanocytes, interrupted only by the inner ends of the porocytes. The amoebocytes get filled with food and become large, they become round to form eggs. Sponges that do not have spicules are supported by strong, flexible fibers made of a protein called spongin. Thus, they show affinities with Protozoa as well as with Metazoa.
1. The canal system helps the sponges in nutrition, respiration, excretion and reproduction. 1. Sponges are clumps of cells arranged around masses of tubes. Though sponges are multicellular animals their cells do not form organised tissues. Characteristic skeleton consisting of either fine flexible spongin fibres, siliceous spicules or calcareous spicules. A pumping action moves the water through the sponge and out through a large hole at the end of each tube.
Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates.
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Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA). In some cases there is also a narrow current tube, the prosodus between the incurrent canal and the flagellated chambers, such a condition is called diplodal. on.
In the aphodal leuconoid type of canal system, the flagellated chambers are small and rounded.
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The movement of whiplike cells in the center of the sponge draws water through the holes and into the sponge. Examples of common gastropods include all varieties of sna… Flamingos are five species of large, colorful, very unusual-looking wading birds that encompass the family Phoenicopteridae. Sponges can be soft or hard, flexible or brittle. 1. Species.
rather similar, being generally dark-blue or… They are attached to the substratum by root tufts. The main characteristics of the leuconoid type of canal system are the limitation of the choanocytes to small chambers, the great development of the mesenchyme, and the complexity of the incurrent and excurrent canals.
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off. They have a skeleton of separate calcareous spicules which are monaxon or tetraxon; tetraxon spicules lose one ray to become triadiate. Both ectoderm and endoderm layers secrete mesogloea and its amoebocytes. 3. 3. Others are treelike or bushy. 14.
Most sponges need a firm surface on which to attach, such as rocks or the skeletons of dead sponges and coral. 4. But in most syconoid sponges, the walls of the radial canals fuse in such a manner as to leave between them tubular spaces, the incurrent canals, which open to the exterior between the blind outer ends of the radial canals by apertures termed dermal ostia or dermal pores.
Monaxon megascleres in the form of tylostyles.
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13. The sponges are mostly attached forms; they are found attached to stones, shells, sticks, sea weeds, etc. 2. 10. Skeleton composed of network of spongin fibres only.
The incurrent canals lead into the small rounded flagellated chambers by opening still termed prosopyles.
The osculum acts only as exhalent aperture. They are solitary or colonial; body shape vase-like or cylindrical. In addition to the protection, the animals living inside the sponge body get a rich food supply from the water circulating through them.
1. 3. Sponges use either sexual (SEK-shuh-wuhl) or asexual (ay-SEK-shuh-wuhl) reproduction. The body of many sponges is supported by tiny rods or star-shaped structures called spicules (SPIH-kyoolz).
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