Clear concept Of porifera phylum

Clear concept Of porifera phylum

1. Presentation on Phylum Porifera

2. WHAT IS PORIFERA Porifera , a phylum within the Kingdom Animalia , is commonly refered to as sponges . The sponge or poriferans , named from Latin porus “pore” and ferre “to bear”, believed that they are the simplest animals on the earth because they have not true tissues such as muscles, nerves, and internal organs. So many scientists who study this animal separated them from other Metazoans to phylum of the Parazoa branch of Kingdom A nimalia .

3. Definition of Porifera The Porifera may be characterized as a sedentary, aquatic, mostly marine, solitary or colonial, radially symmetrical or asymmetrical, multicellular organisms; without definite organ systems, mouth and nervous tissue; with a pores, canals and chambers through which a water current flows.

4. Example of Porifera

5. Example of Porifera

6. General characterastics   # porifera are aquatic, mostly marine animals. # They are solitary or colonial. # Body is radialy symmetrical or asymmetrical and multicellular . # Their body bears a lot of pores which called ostia .

7. Continue...... # Body shape is cylindrical, branching, vase like or globular. # They have no definite organ system like as mouth and nervous tissue. # Respiration occurs through the osculam or oscula with the current of water.

8. Continue...... # reproduction both asexual or sexual. Asexual reproduction by means formation of buds and gemmules . # Sexual reproduction by means of ova and sperms. # Fertilization is internal and cleavage holoblastic .

9. Classification of Porifera P orifera classify upto 3 classes on the base of skeleton type 1. Class Calcarea : Have a skeleton of separate calcareous spicules ( monoxon or tetraxon ) Solitary or colonial Body shape is base - like or cylindrical Canal system asconoid , syconoid or leuconoid Example: Leucosolenia

10. 2.Class Hexactinellida : Called glass sponges Body shape cylindrical or funnel No epidermal epithelium Choanocytes line finger shaped Example: Hyalonama

11. 3. CLASS Demospongiae : Larged sized, solitary or colonial Skeleton may be spongin fiber Canal system leucon type Example: Oscarella

12. Representative of Porifera sycon Systematic position: Phylam : porifera Class : calcarea Order : Heterocoela Family : Sycettidae Genus : scypa (= sycon )

13. S ome types of sponges:

14. General characters: *Pore bearing ;asymmetrical or symmetrical. *Skeleton consist of calcareous spicules . *canal system syconoid type. Habits and habitats: Scypa formerly called sycon or grantia is widely diatributed with numerous species. It is a small marine sponge found permanently attached to submerged rocks and other solid substratam,in shallow waters near the coast,just below the low tide mark.It is a branching,colonial sponge,though solitary individuals are also found.

15. C anal system of sponges Three types of canal system of sponge: 1. Asconoid : Simplest, radially symmetrical, vase like body. Body wall composed of an outer and inner epithelium with a mesenchyme . Mesenchyme contains skeletal spicules . The wall is perforated by numerous microscopic aperture which called ostia . Each pore is intracellular. Water current impelled by the flagella of the choanocytes passes through the incurrent pores into the spongocoel and out through the osculum

16. Flow chart……. Water current from exterior ln current pores spongocoel osculum water out. Example:Leucosolenia

17. 2. Syconoid : First stage above the asconoid type. IT IS FOREMED BY THE out pushing of the wall of an asconoid sponge at regular interval into finger like projection called radial canal. At first these radial canals are free projection and the outside water surround their whole length, for there are no definite incurrent channel. But in most syconoid sponge, the wall of the radial canal 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 .

18. Co ntinue…. The water current in syconoid sponges takes the following route: Dermal pores lncurrent canal prosopyles radial canals lnternal ostia spongocoel osculum out. Example: Scypha

19. 3. Leuconoid : 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. The course of water current is dermal ostia lncurrent canals prosodus (if present) prosopyles flagellated chambers apopyles aphodus (if present) excurrent canals larger channels oscula out. Example: Oscarella

20. General Morphology The body of a simple sponge may be compared to a vase, attached at the base, open at the top, and with the wall perforated by numerous canals opening externally as ostia . The canals open into a central cavity, the spongocoel , which itself opens through the osculum at the top of the organism. Although the sponges have very simple internal structure that consist of soft parts and hard parts (Skeleton) .

21. Soft parts Porocytes , Flat epidermal cells, and Amoebocytes . The wall of a sponges have two layaers of cells. The outer layer, epidermis or The cellular part of the sponges body consist of Choanocytes , ectodermis , is composed of a single layer of thin, flat cells. It’s seems to function chiefly as a protective covering. The inner layer, or Flat epidermal cells , lines the spongocoel and chambers and parts or the whole of the canals in the wall. It is consists of

22. It is consists of Choanocytes or collar cells , which have a collar surrounding the flagellum, are both the food-gathering cells and the pumping cells of the water circulatory system that operate through central cavity ( cloaca or spongocoel ) which opens at the top to the osculum . Porocytes are tubular cells that make up numerous tiny holes outer surface of the sponge known as ostia or dermal pores. Amoebocytes (live between the choanocytes and the epidermis) carry out many of the sponge’s functions such as transport of nutrients, secretion of the spicules , and production of gametes.

23. Hard parts – Skeleton Some sponges have not skeleton because their body may be composed of a simple colloidal jelly but most of sponges have material consists of calcareous, siliceous, or hard organic spicules . The skeleton is secreted by spicules that can be grouped by size, number of axes, and number of rays.

24. Size : 1. Megascleres - large spicules 0.1 mm to over 1.0 mm long. These may fuse to form a coherent framework.

25. 2. Microscleres - small spicules 0.01 mm to 0.1 mm long. These are scattered all over the body. Axes : 1. Monaxons - one axis

26. 2. Triaxons - three axes

27. 3. Tetraxons - four axes

28. 4. Polyaxons

29. 5. Desmas

30. Rays: 1. Monactine - one ray 2. Diactine - two rays 3. Triactine - three rays 4. Hexactine - six rays 5. Polyactine - Multi-rayed (Lehmann, 1983 Reproduction The reproduction of sponges exhibits many characteristics of sessile or slow-moving animals. Asexual reproduction is quite common, and occurs in one of two ways: 1.)Fragments that break off from the parent animal may become new sponges OR, 2.) Gemmules : collection of amoebocytes within a hard, protective outer layer.

31. Sexual reproduction   in sponges is highly  specialized.  The simplest and most primitive form of fertilization is external, with the sperm and egg cells shed into the water.  However, in most sponges, fertilization is  internal .  The sperm cells are carried by the water currents out of the osculum of one sponge and into the interior cavity of another sponge.  There they are captured and transferred to ready eggs.  Most sponges even provide a certain amount of maternal care, retaining the toung during the early stages of development.  The embryonic  (not

32. full grown, still developing) sponge develops into a free-swimming larva that locates an appropriate site, settles and attaches, and develops into an adult sponge.      Most kinds of sponges are hermaphrodites, meaning the same individual has both male and female reproductive structures and produces both sperm and egg cells.  This is a great advantage for animals with little or no motilitty , as a hermaphrodite can mate with any partner, with no limitations concerning gender. Sponges are very interesting and unique, with many different and beautiful species.  For a much more detailed

33. Ecology Sponges are ecologically variable and adaptable. Sponges mostly living in marine which can be found attached to surfaces anywhere from the intertidal zone to as deep as 8,500 m. Some species adapted to freshwater environment. Modern calcisponges , demosponges , and sclerosponges mostly occupy shallow water. Calcisponges are usually found in water less than 100 meters, whereas sclerosponges can be found to 200 meters. Hexactinellids are restricted to deeper water (Rigby, 1987). Most sponges are sessile so they feed by filtering out of the water plankton and other suspended organic material (Dodd, 1981).

34. Geological distribution Sponges are worldwide in their distribution, and range from waters of the polar regions to the tropical regions. In the Paleozoic and Mesozoic, shallow-water sponges were important reef builders. Demosponges were vital frame builders in reefs of North America, Europe and Australia throughout the Ordovician, Silurian, Devonian, Permian, and Triassic. Hexactinnelids were important frame builders in Jurassic reefs of Europe. Sclerosponges of the Paleozoic and Mesozoic were also associated with reefs. Calcisponges also contributed to Permian and Triassic reef complexes of North America and Europe (Rigby, 1987).

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