What is an animal
Structure of animals
Animals are composed of tons of cells
cells, tissue, organs, system
ex: bone tissue
Functions of animals
Obtaining food and oxygyn
animals' bodies cannot make their own food
has to obtain food and oxygen itself
food provides material for animals' growth and gives energy to them
Keeping conditions safe
Animals have to maintain a stable environment in order to survive
Ex: if cells get too hot they start to die
movement
all animals must move in some way
If animals didnt move at all they would not be able to obtain food and water
Reproduction
because no animal lives forever animals must reproduce to keep their kind alive
most animals reproduce sexually
Classification of animals
Biologists have identified more than 1.5 million species
they sort them into categories
the branching pattern in the figure shows how closely the animals are related by the space of the branches