General characteristics of the Kingdom Animalia are as follows:

Animals are eukaryotic, multicellular and heterotrophic organisms.

They have multiple cells with mitochondria and they depend on other organisms for food.

Habitat - Most of the animals inhabit seas, fewer are seen in fresh water and even fewer on land.

There are around 9 to 10 million animal species that inhabit the earth. Only 800,000 species are identified.

Biologists recognize 36 phyla in the animals kingdom.

Size - The sizes of animals ranges from a few celled organism like the mesozoans to animals weighing many tons like the blue whale.

Animal bodies - Bodies of animals are made of cells organized into tissues which perform specific functions. in most animals tissue are organized into complex organs, which form organ systems.

Cell structure - The animal cell contains organelles like the nucleus, mitochondria, Golgi complex, ribosomes, endoplasmic reticulum, lysosomes, vacuoles, centrioles, cytoskeleton.

Animals are made up of many organ systems, that aids in performing specific functions that are necessary for the survival of the organism.

Organ systems are skeletal system, muscular system, digestive system, respiratory system, circulatory system, excretory system, reproductive system, immune system and the endocrine system.