What Is an Animal?Chapter 9 Section 1

Structure of Animals

Composed of…◦Cells: basic unit of structure and function of living things

◦Tissue: group of similar cells that perform a specific function

◦Tissues combine to form organs, more complex job

◦Organs combine to form systems

Functions of Animals

Obtaining food and oxygen

Keepings conditions stable

MovementReproduction

Food and Oxygen

Food provides animals with raw materials for growth and energy

Most animals take food into a cavity inside their bodies◦It is then digested/broken down

To release energy from food, the body’s cells need oxygen

Adaptations

a structure or behavior that allows animals to perform basic functions in their environments

Movement

Some animals move around their entire life◦Humans, frogs, dogs (swim, walk, hop)

Some animals move for part of their lives◦Oysters, barnacles

Why do animals move?◦Obtaining Food◦Reproducing

Reproduction

Sexual Reproduction◦New organisms develops from the joining of two sex cells (male sperm cell and female egg cell)

◦Combination of both parents characteristics

What is the joining of an egg cell and a sperm cell called?

Fertilization

Reproduction Continued

Asexual Reproduction◦Process by which a single organism produces a new organism identical to itselfSea AnemonesSingle-celled organisms such as the archaea, bacteria, and protists

Classification of Animals

1.5 million speciesBiologists have classified animals into

about 35 major groups called phylumEvidence suggests that all animals

arose from single-celled ancestorsWhen classifying, biologists consider

◦How it looks◦How it develops◦The content of its DNA

Vertebrate vs. Invertebrate

Vertebrates◦animals with a backbone

Invertebrates◦animals without a backbone

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