1. Comparative Anatomy

2. There is a great deal of diversity in the living world
There is a great deal of diversity in the living world. Most multicellular organisms have organ systems that perform similar functions. However, these systems perform their functions in a variety of ways. While some systems are highly advanced, many are primitive. Every system must perform its function in order for the organism to survive.

3. 1. Movement
Movement is not a characteristic of life. Most animals can move, while others cannot.
motile - ability to move from place to place
sessile - “planted” permanently in one place

4. 2. Basic Body Plan asymetrical- no symmetry
spherical - organism can be divided into equal halves through any direction at a central point
radial - organism can be divided into equal halves by passing a plane through the central axis
bilateral - can be divided into equal halves only through a single point

5. 3. Nervous System
a. Some animals are cephalized, which means they have a bundle of nerves concentrated on one side of the body, or a well-developed head.
uncephalized- organism do not have a head.

6. 4. Skeletal System
endoskeleton- internal skeleton, made of bone or cartilage, protection and movement
Exoskeleton external skeleton composed of chitin, protection
Hydrostatic - liquid skeleton, movement

7. 5. Digestive System
a. intracellular digestion - food is broken down in individual cells
b. extracellular digestion - food is broken down in a specialized tract composed of organs
i.Digestive systems are specialized to the organisms diet
1.Examples:
a.Birds - crop
b.Cows - rumen

8. Bird/ Cow

9. 6. Circulatory System
a. Open circulatory system – blood is only partially contained within a system of blood vessels. Blood comes in direct contact with tissue inside a cavity b. Closed circulatory system – blood is always contained within a system of blood vessels. Blood never comes in direct contact with tissues. More efficient than an open system

10. 7. Reproductive System
a. Most animals reproduce sexually, which provides genetic variation
External fertilization – eggs are fertilized outside the body
Internal fertilization – eggs are fertilized inside the body
b. Some small invertebrates reproduce asexually. There is no genetic variation, but it does not require a partner.