2.5. KINGDOM ANIMALIA

This kingdom is characterised by heterotrophic eukaryotic organisms that are multicellular and their cells lack cell walls. They directly or indirectly depend on plants for food. They digest their food in an internal cavity and store food reserves as glycogen or fat.

Kingdom Animalia includes all multicellular organisms that cannot make their own food, meaning they need to eat other living things or plants. These organisms have eukaryotic cells, which means their cells have a nucleus and other cell structures. A key feature of animals is that their cells do not have cell walls (unlike plants), which gives them flexibility to move and grow. Animals store energy in the form of glycogen and fats while they break down food in an internal digestive system, allowing them to absorb nutrients.

Think of animals like we approach a meal. Just like we don’t have a cell wall blocking our mouth, animals can move freely to find food and eat. For example, when you eat a pizza, your body breaks down the food in your stomach to extract energy and nutrients, similar to how animals operate internally.

Their mode of nutrition is holozoic – by ingestion of food. They follow a definite growth pattern and grow into adults that have a definite shape and size.

Animals typically eat food through a process called holozoic nutrition, meaning they ingest solid food. This process involves taking food into the body, breaking it down into smaller components, and then absorbing the nutrients into their cells. Animals usually follow a specific growth pattern, starting from a juvenile stage and developing into a fully grown adult with a specific size and shape based on its species.

Consider how a caterpillar munches on leaves. It consumes leaves (its food), digests them, and then grows larger. Eventually, it undergoes a transformation to become a butterfly. This growth process is set and expected, just like most animals have set forms and sizes they reach.

The sexual reproduction is by copulation of male and female followed by embryological development.

In animals, reproduction typically involves sexual reproduction, where male and female individuals mate (copulation) to produce offspring. After mating, the fertilized egg goes through embryological development, where it grows from a single cell to a complex organism. This process is essential for the continuation of species, ensuring genetic diversity and adaptation to environments.

Similar to how human babies are conceived, animals usually need a male and female to come together. For example, when a male and female dog mate, the female can conceive puppies. Just as puppies grow inside their mother until they are ready to be born, embryos in other animals develop in a similar protective environment until they are ready to face the world.

Higher forms show elaborate sensory and neuromotor mechanism. Most of them are capable of locomotion.

Animals exhibit a range of complex behaviors and physical adaptations, thanks to developed sensory organs (like eyes, ears) and neuromotor systems (brain and muscles). These features allow them to interact with their environment actively and often move from one place to another, a capability known as locomotion. From simple movements like crawling to complex actions like flying or swimming, locomotion is crucial for survival as it helps animals find food, escape predators, and reproduce.

Imagine your dog running to you when you call its name; it uses its hearing and sense of smell to find you. Similarly, when birds migrate thousands of miles, they rely on their sensory skills to navigate. This locomotion is essential for their life—it’s how they seek food, find mates, and adapt to changing environments.

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