Zoology Point

  In this article we will discuss about Sponges:- 1.  Taxonomic Retrospect of Sponges 2.  Definition and Origin of Sponges 3. General Features 4. Habitat 5.  Structural Peculiarities 6. Development 7. Affinities 8. Regeneration 9. Phylogeny. Contents: Taxonomic Retrospect of Sponges Definition and Origin of Sponges General Features of Sponges Habitat of Sponges Structural Peculiarities of Sponges Development of Sponges Affinities of Sponges Regeneration in Sponges Phylogeny of Sponges 1. Taxonomic Retrospect of Sponges : Up to 18 th  century sponges were not con­sidered as animals. Ellis (1775) established the animal nature of the sponges. Linnaeus, Lamarck and Cuvier considered the sponges related to anthozoan polyps and included the sponges within zoophytes or polyps. Sponges were included under coelenterates throughout much of the nineteenth century, though de Blainville (1816) proposed to separate sponges from coelenterates and cre­ated a group Spongiaria ha...

As a group the protozoa are most primitive and are inhabiting the earth for about a billion and half years. Fossil forms of radiolaria and foraminiferans, half a billion years old, have been recorded.                                           Origin : Pre-Cambrian Taxonomic Retrospect : Leeuwenhock (1676) first gave prelimi­nary accounts of some protozoan forms after the discovery of microscope. Goldfuss (1818) coined the term Protozoa but he included many non-protozoan forms under protozoa. Von Siebold (1845) recognised the unicellu­lar nature of the protozoa and established the term Protozoa in its true sense. The zo­ologists like Doflein (1901), Colkins (1901, 33), Kudo (1931, 77), Hyman (1940), Honigberg (1964), Grell (1973), Corliss (1967, 84), Cavalier-Smith (2002) and Brusca and Brusca (2003) have classified the protozoa in different angles and have discussed on dif­ferent asp...