Tiêu đề ANIMAL KINGDOM (NON-CHORDATES)_1-45.pdf ✅

NARAYANA GROUP 1 NEET ZOOLOGY VOL-I ANIMAL KINGDOM (NON-CHORDATES) Animal Kingdom (Non Chordates) CO N T E N TS * Introduction * Basis of classification Levels of organisation Body segmentation Symmetry Coelom * Classification of animals Porifera Coelenterata Ctenophora Platyhelminthes Aschelminthes Annelida Arthropoda Mollusca Echinodermata Hemichordata  Salient features and classification of animals- nonchordate up to phyla level (Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata). NEET SYLLABUS 4
NEET ZOOLOGY VOL-I 2 NARAYANA GROUP ANIMAL KINGDOM (NON-CHORDATES) INTRODUCTION * To estimate the number of animals in nature is not possible. Many of them inhabit the earth today and many others have lived here during the past. These animals vary very much in their shape and size, habit and habitat, colour, form and weight as well as in their distribution. More than one million animals (1,000,000) have been discovered by Zoologist and there are still many more which are unknown. * On an estimation about 5 to 20 million kinds of organisms exist on our planet. Out of these about 1.2 million animals and 0.2 million plants species have been identified, given scien- tific name and classified. Basis of Classification * Arrangement of cells, body symmetry, nature of coelom, patterns of digestive, circulatory or reproductive systems are basis for animal classification. LEVELS OF ORGANIZATION Following are the different levels of organization in animals from simpler to complex state:  Protoplasmic grade – In this grade all life activities are confined within the boundaries of a single cell which is a structural and functional unit of life. e.g. Protozoa and other unicellu- lar organisms. * Cellular grade – It is a loose association or aggregation of cells that are functionally differ- entiated, e.g. sponges. Division of labour occurs among cells in sponges * Tissue grade – An aggregation of cells which act in co-ordination. In this cells performing the same function are arranged into tissues. E.g. Cnidarians, Cteno- phores. * Organ grade – When tissues aggregate to form a particular organ, each of which is special- ized for particular function first appeared in platyhelminthes. * Organ system grade – When organs work together to perform some common functions such as digestion, respiration, circulation etc. e.g., most of the higher animals such as annelida, arthropoda, mollusca, echinodermata and chordata. * Blind Sac or Incomplete gut (Two way gut) – The body resembles a sac and contains a single cavity with one opening that serves as both mouth and anus and helps in both inges- tion and egestion e.g., Platyhelminthes (flatworms). * Tube within a tube or Complete gut ( one way gut) – The body is made up of two tubes, outer body wall and the inner digestive tract. e.g. Annelida and other higher phyla. In these animals gut has two openings such as mouth for ingestion and anus for egestion. * Open type of circulation - In which the blood is pumped out of the heart and the cells and tissue are directly bathed.e.g., Arthropoda, Non - Cephalopod Molluscs, Hemichordates and Urochordates. * Closed type of circulation - In which the blood is circulated through a series of vessels i.e. arteries, veins and capillaries. e.g., Annelida, vertebrata, Cephalopoda (Mollusca), Cephalochordata. Symmetry  The arrangement of body parts in a geometrical pattern is called symmetry. Types of symmetry  Spherical symmetry – Found in spherical body. All planes that pass through the center will cut it into similar halves. e.g. Some protozoans like Volvox, Heliozoa, Radiolaria. * Radial symmetry –These animals are cylinder or umbrella shaped. Any plane passing through central axes in a radiating manner divide the body into equal halves. e.g. Coelenter- ates, Ctenophores and Echinoderms  (a) Biradial symmetry – divides the animal into two equal halves only in two planes. e.g. Ctenophora and most anthozoans (e.g. Sea anemone)