13. The oscules, quite visible, are located at the intersections of the largest tubes. Such inclusion has recently been challenged by O. Tuzet, who after studying sponges for many years has again claimed that porifera has given rise to the true metazoans. Inner surface of the body is lined by specialised cells, the choanocytes. A sponge’s skeletal type adapts well to its particular habitat, allowing it to live on hard, rocky surfaces or soft sediments such as sand and mud. (With Methods)| Industrial Microbiology, How is Cheese Made Step by Step: Principles, Production and Process, Enzyme Production and Purification: Extraction & Separation Methods | Industrial Microbiology, Fermentation of Olives: Process, Control, Problems, Abnormalities and Developments, The best answers are voted up and rise to the top. Sponges are thought to have evolved around 500 million years ago, and today there are more than 5,000 known species of sponge with another 5,000 species thought to have not yet been discovered. Most calcareous sponges in the fossil record were classified as either stromatoporoids, chaetetids, archaeocyaths, inozoans, pharetronids, or sphinctozoans. However, they … After a brief swimming period they become attached by their anterior ends and develop into flattend plate-like structure with an irregular outline. Habitat information for each species was taken from Fetzner ... Wörheide G (2006) Non-monophyly of most supraspecific taxa of calcareous sponges (Porifera, Calcarea) revealed by increased taxon sampling and partitioned Bayesian analysis of ribosomal DNA. They are common in the Paleozoic and Mesozoic, however, rare in the Cenozoic. The genus Clathrina (Gray, 1867) has an asconoid aquiferous system, one of the simplest organization among sponges, which means that all the cavities are lined by choanocytes (Klautau & Valentine 2003). The cells of sponges show a high degree of independence. Vital functions are performed by independent activities of the cells. Calcareous sponges (Class Calcarea) include about 675 accepted extant species (Van Soest et al., 2011), which are exclusively marine. The constituent cells exhibit less differentiation but are involved in several complicated organisations, i.e., formation of gemmules. 5. 4. They have all in common certain structural features. They lack mouth and digestive cavity. Common along the Atlantic coast of Europe, from the Mediterranean to the coast of Norway. Molecular Phylogenetics and Evolution 40: 830–843 . This phenomenon is called de-differentiation (Fig. The amoebocytes with blunt pseudopods, conspicuous nuclei with large nucleolus are referred to as the archeocytes. Most sponges live in a salt water environment, attached to objects on the sea floor. Give the general characteristics of the Phylum Porifera. Clathrina clathrus is a calcareous sponge of 10 cm in diameter forming a tangle of tubes which are between 0,5 and 3 mm in diameter and interconnected in a very dense network. The closure of the pore is effected by the advancement of a thin cytoplasmic sheet called the pore diaphragm from the margin to the centre at the outer end of canal. In tropical coral reefs, they dwell mainly in shaded and/or cryptic habitats and prefer calmer waters. Disclaimer Copyright, Share Your Knowledge
Porocytes are tubular cells extending from the epidermis to the spongocoel. Members of this group include glass sponges, demosponges, and calcareous sponges. Explain the differences between the following types of cells found in the mesohyl; Pinacocytes and Choanocytes. 4. Sponge: zooxanthella symbioses are especially important given that Symbiodinium are predominantly associated with the bioeroding sponges that dissolve calcareous structures (e.g. Certain amount of organisations like connective tissues, nervous tissues, are expected to be present even at the simplest form. Development 7. Be able to distinguish the difference between the following structures; osculum, ostia, choanocytes and mesohyl.
2020 calcareous sponge habitat