Water canal system in porifera. Canal Systems Encountered in Different Sponges 2019-02-10

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Phylum Porifera

water canal system in porifera

The choanocytes have collar of microvilli around the flagellum. Water leaves the sponge through the osculum. It contains different kinds of amoebocytes and triradiate spicules formed of calcium carbonate. Ascon type It is simplest and least common sponge body form. Following types of cells are present in phylum porifera.

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Canal System in Sponges (Porifera)

water canal system in porifera

Spongocoel opens to the outside by the osculum. The rate of water flow is slow as the large spongocoel contains much water which cannot be pumped out through a single osculum. The food and oxygen are brought through this current while excreta and reproductive bodies are excluded through this current. It also occurs in Olynthus stage of some newly settled calcareous sponges e. But as the pressure in the incurrent and excurrent canals is the same, there must be a difference of pressure within the chamber itself and the lower pressure must be towards the periphery. Despite the folding of the body wall, the syconoid sponges still retain the radial symmetry.


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Role and Significance of Canal System in Sponges

water canal system in porifera

The ostia open in these spaces which lead into incurrent canals. There are a number of flagellated chambers {radial canals in the upper wall into which the prosopyles open. This washed and dried spongin produce a commercial sponge. In this type the radial symmetry is lost due to the complexity of the canal system and this result in an irregular symmetry. The spongocoel opens to the exterior by a large single osculum. Ostia are the outer openings of porocytes.

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Basic Concept of Invertebrate Zoology Knowledge: Types of Canal System of Porifera

water canal system in porifera

Following canals are formed by the folding of its wall: a Incurrent canal: The invaginations of the body wall of sycon form incurrent canals. These larvae may be parenchymula larva or amphiblastula larva. It also carries away metabolic and digestive wastes. The canals have openings to the outside which are called pores, where the water enters the sponge system these pores are usually small and are called 'ostia' and where the water leaves the sponge system the pores are larger, often singular and are called 'oscula' singular osculum. Canal system in sponge furnishes a peculiar kind of pump, driving in and out the current of water. The choanocytes are arranged in such a way that their collars are oriented towards the apopyles. Ecology All sponges are filter feeders on small to extremely small particles and most are sedentary or immobile as adults, i.

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Canal Systems Encountered in Different Sponges

water canal system in porifera

Incurrent canals open into small, rounded chambers provided with flagellated cells. These are thin, flat epithelial cells covering the exterior surface and some interior surfaces. Thus excurrent canals communicate with the outside through a small spongocoel and an osculum. Some species have been shown to have a preliminary negative geotaxis while most species have shown a preference for surfaces with an algal or bacterial film. Rather complex water passage a twisted route. These canals are usually branched.

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Porifera

water canal system in porifera

Coordination There are two forms of coordination in sponges: a Coordination by external factors: Sponges do not have nerve cells to coordinate body functions. More than 5,000 species are known, most of which occur in shallow coastal waters and in the deep sea. The skeletal elements of sponges are variable and important in taxonomy. The function of the canal system is also excretory. The conditions become favorable in the spring. Etymology:- From the Latin porus for pore and Ferre to bear, hence an animal with with pores. Body wall is secondarily folded to form incurrent and radial canals, which open into the spongocoel by an opening called apopyle.

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Water canal (aquiferous) system

water canal system in porifera

There are nine thousand species of sponges. Mostly individual cells show response to a stimulus. Sponge skeleton The skeleton of spicules and spongin provides the support to keep the pores open. Types of sponge cell Pinaocytes. They form the lining of the inner chamber. The Hexactinellida or 'Glass sponges' have spicules made from silica that are 6 rayed.

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Canal system

water canal system in porifera

Leucon type Leucon sponges have an extensively branched canal system. Choanoderm is composed of choanocytes or collar cells. The flow of the water is maintained by the beating of the flagella of the collar cells. Luecon type canal system is formed by the evolution of simple canal system. The syconoid sponges pass through an asconoid stage in their development suggesting that they have evolved from some ancestral asconoid. Oxygen is taken in by simple process of diffusion and carbon-dioxide is given out. The perforations of the body of the sponge by a large number of ostia is characteristic of phylum Porifera.


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Porifera (sponges)

water canal system in porifera

Here the spongocoel is much reduced. Extending from the centre of this collar is the single flagellum whose beating drives the water currents that keep the sponge alive and healthy. The incurrent canals leas into adjacent radial canals through the minute openings called prosopyles. Many if not most of these canals are lined with special flagellated cells called 'choanocytes'. The se­lected food are digested by choanocytes of the flagellated chambers and serves the pur­pose of nutrition.

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