UNIT Living World of Animals - 7 Diversity in Living Organism - Kingdom Animalia Learning Objectives At the end of this Unit the students will be able to understand, the classification of various types of animals makes it easier to observe, identify and study the different groups of animals on the basis of certain characteristics they have in common list out the general characteristics of animals based on grades of organization, types of symmetry, coelom and various body activity recognize that binomial classification has Latin and Greek words given to each animal and plant, the first name is genus and second as species recall the salient features of each phylum Introduction appearances? What factors are significant for their classification? The enormous variety of Long ago, when human civilization living organisms surrounding us is was confined to small place, the number incomprehensible. About 1.5 million and variety of animals and plants that they species of animals are already described were aware was limited. However, when and named. Without suitable method the European explorers went around the of classification, the study of various world during the 15th and 16th centuries, organisms would be difficult. they could collect information on plants For example, among the butterflies, and animals from across the world. The it is difficult to identify their varieties. immense diversity in shape, size and Because there are different colour of features baffled them. butterflies (blue, red, brown, yellow) and The first systematic approach to butterflies with spots (big and small). the classification of living organisms was Tigers and zebras have stripes. made by a Swedish botanist, Carolus On the other hand tigers look more like Linnaeus. He generated the standard cats and zebras are more like horses. system for naming organisms in terms Can we classify them based upon their of genus, species and more extensive groupings using Latin terms. 7. Living World of Animals 155 IX_Science Unit-7.indd 155 27-03-2018 12:32:02 For example, the tiger is a carnivore You are in a village, which is part of and the zebra is an herbivore, both are a taluk. Your taluk is part of district, striped animals, but the tiger resemble which falls under a state- Tamilnadu. a cat more than zebra. However all Tamilnadu is a state in India which is the three produce milk and feed their a country in South East Asia. Similarly, young ones. the Tiger is classied as Kingdom: Taxonomists realized that wide Animalia; Phylum: Chordata; Sub features are shared for the ranking of phylum; Vertebrata; Class: Mammalia; higher group in classification. Therefore Subclass: Eutheria; Order: Carnivora; characters that strike the eye, like the Family: Felidae; Subfamily: Panthernae; tiger’s stripes, are often less significant Genus: Panthera; Species: tigris. Find than subtler ones, such as how many toes out the classication of cat and humans? the animal possesses. Different types of animals produce milk to feed their young ones. lassifiatin iin 7.1 Therefore all of them could be grouped Organisms into one major category, known as mammals. Higher ranks are more Imagine a bacteria, neem tree and toad. comprehensive. All of them are living things and their Human beings have a wonderful basic unit is a cell. However, one major capacity to discriminate different difference is that the cells in neem tree and animals. While walking through a field toad have nucleus, whereas the bacterium we may come across a jumping frog. Is it has no nucleus. Thus all life can be divided a frog or a toad? We may see a snake. Is it into two major categories Prokaryotes and poisonous or not? We may hear a bird call Eukaryotes. Among the eukaryotes like but we are not familiar with it. Sometimes pond algae, fern and a rabbit, the pond a fish may be seen in a temple tank. algae is a single celled organism, whereas What kind is it? rest are multicellular organisms. On the In order to nd an answer to such basis of significant characteristic features questions, we should know how to identify like the presence or absence of cell wall animals. For a biologist it is necessary to and the photosynthetic activity, the identify the organism, which have a name organisms (living beings) are divided into for identication and to know the group it major groups as shown in Figure 1 and 2. belongs to. riteria r lassifiatin Ta onomy 7.2 of Animal Kingdom It is the theoretical study of classification including its basic principles, procedures Look at this list of animals: sponge, rotifer, and rules. jelly fish, flatworm, roundworm, snail, earthworm, grasshopper, star fish and peacock. lassifiatin Among the above listed animals, It is the ordering of organism into sponge does not have any true tissues. groups on the basis of their similarities, We can divide the animalia into two major dissimilarities and relationship. 7. Living World of Animals 156 IX_Science Unit-7.indd 156 27-03-2018 12:32:02 F g r e Classifi cation of kingdom Animalia based on common features F g r e Classifi cation of kingdom Animalia divisions - those with true tissues and those 1. Grade of organization – Animals without true tissues. e group of animals are grouped as unicellular or that lack true tissues are called as Porifera. multicellular based on the number It is seen that the jelly fish and star of cells. fish have radial symmetry, while if we look 2. Symmetry – It is a plane of at flatworm, roundworm, rotifer, snail, arrangement of body parts. Radial earthworm, grasshopper and peacock symmetry and bilateral symmetry are have bilateral symmetry. the two types of symmetry (Figure 3). 7. Living World of Animals 157 IX_Science Unit-7.indd 157 27-03-2018 12:32:02 Radial Vs Bilateral symmetry ese layers give rise to dierent organs, as the embryo becomes an adult. If an organism has two germ layers, the ectoderm and the endoderm it is said to be diploblastic. If they have three germ layers, the ectoderm, the mesoderm and the endoderm they are triploblastic animals. 4. Coelom – Coelom refers to a fluid-filled cavity inside the body. It separates the digestive tract and F g r e Radial and Bilateral Symmetry other organs from the body wall. A true body cavity or coelom is one that is located within the In radial symmetry the body parts are mesoderm. Based on the nature of arranged around the central axis, if the coelom, animals are divided into we cut through the central axis in any 3 groups (Figure 4). Organisms like direction, it can be divided into similar the earthworm are called coelomates halves. E.g. Hydra, jelly sh and star or eucoelomates because they sh. In bilateral symmetry, the body have true coelom. Tapeworm is an parts are arranged along a central axis, example of an acoelomate because it if we cut through the central axis, we does not have a body cavity. Animals get two identical halves E.g. Frog. like the roundworm have a body 3. Germ layers – Germ layers are formed cavity but it is located between the during the development of an embryo. endoderm and the mesoderm. F g r e Types of Coelom 7. Living World of Animals 158 IX_Science Unit-7.indd 158 27-03-2018 12:32:03 F g r e Classifi cation of kingdom Animalia using diff erent criteria is is considered to be a false coelom 7.3 Phylum - Protozoa and these organisms are called pseudocoelomates. (Proto- rst; zoa-animals) is phylum includes a great diversity of small, Characters like presence or absence of microscopic organisms. ese are single body cavity (coelom), segmentation, celled eukaryotes. eir locomotion occur exoskeleton, jointed legs (appendages), through pseudopodia (false feet), cilia or notochord are used to classify the animalia agella. e nutrition is either autotrophic into ten major Phyla (Figure 5). or heterotrophic. Respiration and excretion is carried out through general body surface More to Know or through contractile vacuole. e y reproduce either asexually or sexually. Deuterostome & Protostome : In the development of embryo, deuterostomes, the first opening Activity 1 (the blastopore) becomes the anus, while in protostomes, it becomes Both are protozoans. Identify their the mouth. names and locomotor organ Kingdom Animalia is divided into two groups, based on the presence or absence of notochord Invertebrata and Chordata (Prochordata and Vertebrata). e groups invertebrata is classi ed as follows 7. Living World of Animals 159 IX_Science Unit-7.indd 159 27-03-2018 12:32:05 More to Know is radial. e body wall is of two layers of cells namely the outer ectoderm and the inner Parasitic Protozoans endoderm, which is separated from each other by a non-cellular jelly-like substance Amoebic dysentery is caused called mesoglea. Due to the presence of two by protozoa called Entamoeba layers in the body wall, they are said to be histolytica which spreads through diploblastic animals. Many coelenterates contaminated food and water. exhibit polymorphism. In this phylum, Malaria is caused by Plasmodium organisms may exist in two dierent body sp. which spreads through female forms namely, a polyp and a medusa. e Anopheles mosquitoes. tentacles bear stinging cells called nematocysts (cnidoblasts). Due to the presence of cnidocil, they are also called as Cnidaria. ey Phylum - Porifera reproduce both asexually and sexually. 7.4 (Pore bearers) These are multicellular, aquatic organisms. They are commonly called sponges. They have a cellular grade of organization without the occurrence of tissues. The body has many pores called ostia and osculum for circulation of water. The body wall contains spicules which form the skeletal framework. They can reproduce both by asexual and sexual methods.