Chapter-Patterns in Life: Diversity and Classification Science Exploration class 9 in english Medium CBSE Notes

Chapter 12. Patterns in Life: Diversity and Classification

This section explains Kingdom Animalia, the fifth kingdom in the Five Kingdom Classification. It describes the general characteristics of animals, their major groups and the gradual increase in body organisation from simple invertebrates to highly developed vertebrates. 

Kingdom Animalia – Multicellular Heterotrophs

Introduction

Kingdom Animalia includes multicellular, eukaryotic organisms that obtain food from other organisms. Unlike plants, animals do not possess cell walls or chlorophyll. Most animals are capable of movement and possess specialised tissues, organs and organ systems that enable them to respond quickly to changes in their surroundings.

Characteristics of Kingdom Animalia

• Multicellular and eukaryotic organisms.
• Cells do not have a cell wall.
• Heterotrophic mode of nutrition.
• Most animals show active movement.
• Possess well-developed tissues and organ systems.
• Respond quickly to external stimuli.
• Reproduce mainly by sexual reproduction.

Habitat

Animals are found in almost every habitat on Earth.

• Forests
• Grasslands
• Mountains
• Deserts
• Freshwater
• Marine ecosystems
• Polar regions

Major Groups of Animals

Animals are broadly divided into two major groups.

Group	Main Characteristic
Invertebrates	Animals without a backbone.
Vertebrates	Animals possessing a backbone or vertebral column.

Invertebrates

Invertebrates form the largest group of animals. They do not possess a backbone and generally have a comparatively simple body organisation.

Examples:

• Sponges
• Jellyfish
• Earthworms
• Snails
• Insects
• Spiders
• Starfish

Vertebrates

Vertebrates possess an internal skeleton with a vertebral column. They have highly developed organ systems and show greater structural complexity than invertebrates.

Major Groups of Vertebrates

Group	Main Features	Examples
Fish	Aquatic animals with gills and fins.	Rohu, Shark
Amphibians	Live both on land and in water.	Frog, Toad
Reptiles	Dry scaly skin; lay eggs on land.	Snake, Lizard
Birds	Body covered with feathers; forelimbs modified into wings.	Pigeon, Eagle
Mammals	Give birth to young ones and feed them with milk.	Human, Cow, Tiger

Comparison of Invertebrates and Vertebrates

Feature	Invertebrates	Vertebrates
Backbone	Absent	Present
Skeleton	Usually absent or external	Well-developed internal skeleton
Body Organisation	Comparatively simple	Highly organised
Nervous System	Less developed	Well developed
Examples	Earthworm, Insect	Fish, Bird, Mammal

Importance of Kingdom Animalia

• Maintain ecological balance.
• Help in pollination and seed dispersal.
• Control populations of other organisms.
• Provide food, clothing and medicines.
• Support agriculture and human livelihoods.
• Contribute to biodiversity and ecosystem stability.

Summary of Kingdom Animalia

Characteristic	Kingdom Animalia
Cell Type	Eukaryotic
Organisation	Multicellular
Cell Wall	Absent
Nutrition	Heterotrophic
Movement	Usually Active
Reproduction	Mainly Sexual

ATP Education Concept Builder

Kingdom Animalia represents the highest level of body organisation among the five kingdoms. The evolutionary trend progresses from simple invertebrates without a backbone to highly developed vertebrates with complex organ systems, allowing animals to adapt to diverse habitats. This gradual increase in complexity reflects the diversity of animal life. (The uploaded pages visible so far introduce Animalia as one of the five kingdoms, while the detailed Animalia section continues in later pages of the chapter.) 

ATP Education Exam Booster

• Remember the general characteristics of Kingdom Animalia.
• Differentiate between invertebrates and vertebrates.
• Learn the five major groups of vertebrates with examples.
• Know the distinguishing features of fish, amphibians, reptiles, birds and mammals.
• Understand the ecological importance of animals.
• Practise comparison-based and competency-based questions on vertebrate classification.

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