zoology Arena

Taenia Parasitic adaptations Tapeworms live as internal parasites and they have to make several adjustments for the same. The following are few of the adaptations made by these tapeworms to make their life easy in their hosts. Presence of enzymatic resistant covering A hard covering called as tegument covers the body of these tape worms. Tegument is enzyme resistant and it protects all the internal organs from the digestive actions of the alkaline fluids of the host. On the other hand tegument is permeable to water and other nutrients. Absence of locomotory organelles This parasite lacks organs for locomotion. As there is no need for any locomotory organs both the adult and larval forms lack cilia or flagella. Osmotic pressure The osmotic pressure inside the body is higher than that of the surrounding host tissue or fluid. This helps the parasite to reside conveniently in the host body. Presence of hooks and suckers for attachment For the attachment purpose a scolex...

Canal system in Porifera (sponges) Body of all sponges is the perforated by large number of apertures through which water enters Inside body and flows through a system of criss-crossing canals collectively forming the canal system which is a characteristic feature of poriferans. Following types of canal systems are found in sponges: Ascon type, with flagellated spongocoel Sycon type, with flagellated radial canals Leucon type, with flagellated chambers Rhagon type, with conical shape and broad base ASCON TYPE This is the simplest type of canal system and is found in  Leucosolenia  and other homocoela. Ostia are present on the surface of body and lead directly into the spongocoel, which is lined by flagellated choanocyte cells. Spongocoel opens to the outside through a narrow circular opening, the  osculum  located at the distal free end of the sponge body. Water enters through ostia into spongocoel and goes out of body through the  osculum . SYCO...

Ecology: Concepts and Applications, 8th edition by Molles and Sher places great emphasis on helping students grasp the main concepts of ecology while keeping the presentation more applied than theoretical. An evolutionary perspective forms the foundation of the entire discussion. The book begins with the natural history of the planet, considers portions of the whole in the middle chapters, and ends with another perspective of the entire planet in the concluding chapter. Its unique organization of focusing only on several key concepts in each chapter sets it apart from other ecology texts. Download the PDF here Click here

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The latest edition of Developmental Biology is a significantly revised version of a modern classis. This textbook provides a diversity of views on how a single cell can give rise to a multicellular organism, enhancing learning with clear prose, colorful images, didactic diagrams, and links to multimedia resources. . . . for students or professors who need a well-rounded, clearly written overview of developmental biology principles this is the most comprehensive textbook currently available." --Kara Cerveny, The Quarterly Review of Biology "Developmental Biology, Eleventh Edition successfully teaches the basis of development in a manner that is digestible and intriguing. It is useful for students who enjoy traditional as well as modern approaches to pedagogy. By systematically reviewing concepts in development, integrating web resources, and providing expansive applications about the subject matter, the textbook is valuable for readers interested in the field." --Jessica...

BY Dr. Otto G. Bier, Dr. Wilmar Dias da Silva, Dr. med. habil. Dietrich Götze, Dr. Ivan Mota (auth.) DOWNLOAD CLICK  HERE