English has become the global language now. Without adequate knowledge in English it is simply difficult to achieve mastery in any subject. The educationists and the policy makers of our country are now patronizing the introduction of English as medium of Uistruction in Secondary and Higher Secondary level. But in our country sufficient books are not available specially of Zoology. However this book has been written to meet the demand of the learners of Higher Secondary level. This book has been written according to the Syllabus of HSC. To meet the demand of the students we published the fifth edition Some chapters of the book have been revised and enriched with new and up dated information.