35 of the EVS textbook 'Wonder World')
3. Draw/ Paste pictures of five different animals belonging to any one animal
subgroup (amphibians, birds, fish, insects, mammals or reptiles). Write three
characteristics/ features of each group of animals.
Answers
Explanation:
Animal Characterization Based on Body Symmetry
At a very basic level of classification, true animals can be largely divided into three groups based on the type of symmetry of their body plan: radially symmetrical, bilaterally symmetrical, and asymmetrical. Asymmetry is a unique feature of Parazoa (Figure 2a). Only a few animal groups display radial symmetry. All types of symmetry are well suited to meet the unique demands of a particular animal’s lifestyle.
Radial symmetry is the arrangement of body parts around a central axis, as is seen in a drinking glass or pie. It results in animals having top and bottom surfaces but no left and right sides, or front or back. The two halves of a radially symmetrical animal may be described as the side with a mouth or “oral side,” and the side without a mouth (the “aboral side”). This form of symmetry marks the body plans of animals in the phyla Ctenophora and Cnidaria, including jellyfish and adult sea anemones (Figure 2b and 2c). Radial symmetry equips these sea creatures (which may be sedentary or only capable of slow movement or floating) to experience the environment equally from all directions.
Three of the vertebrate classes are fish. The most primitive of these is Agnatha click this icon to hear the preceding term pronounced. It consists of jawless fish that do not have scales. These are the lampreys and hagfish. Fish that have skeletons consisting of hard rubber-like cartilage rather than bone are members of the class Chondrichthyes click this icon to hear the preceding term pronounced. These are the sharks and rays. All of the bony fish are members of the class Osteichthyes click this icon to hear the preceding term pronounced. Tuna, bass, salmon, and trout are examples of Osteichthyes.
