2.  All living things are composed of one or more cells.  Cells become specialized to perform certain functions.  Examples 1.Muscle cells: Contract 2.Nerve cells: transmit impulses 3.Gland Cells: Produce and secrete chemicals

3.  A tissue is a group of similar cells performing a similar function. 1.Muscle tissue: Made of many muscle cells that contract. 2.Nervous tissue: Groups of nerve cells, transmits information throughout the body. 3.Glandular tissue: Made of gland cells that produce and secrete chemicals.

4.  An organ is a group of different kinds of tissues working together to perform a specific function. 1.Stomach: An organ made of several types of tissues a)Muscle tissue: in the wall of the stomach contracts to churn and mix food. b)Glandular tissue: the inner lining of the stomach, secretes digestive chemicals (enzymes). c)Nerve tissue: In the wall of the stomach coordinates the mixing and digesting activities.

5.  An organ system is a group of organs that together perform a function for the body. 1.Digestive system: Consists of organs such as the mouth, stomach, and intestine. 2.Excretory system: Consists of kidney, bladder, urinary duct. 3.Integumentary system: Consists of epidermis and dermis.

6.  An organism is an entire living thing with all its organ systems.  A complex organism like a fish consists of systems like the digestive, nervous, sensory, and reproductive.  Fish consist of interacting groups of organ systems that together enable fish to function.

7. 1. Integumentary 2. Skeletal 3. Muscular 4. Digestive 5. Respiratory 6. Circulatory 7. Excretory 8. Reproductive 9. Nervous 10. Endocrine

8.  The integumentary system is commonly called the skin.  Consists of two layers: 1.Epidermis: Outer layer 2.Dermis: Inner layer  Beneath these are the muscles and other tissues that the skin covers. 1.Mucus 2.Pigment grains 3.Scales

9.  The epidermis is made of several sheets of cells that cover the scales.  As cells age, new cells growing underneath push older cells toward the surface.  Old surface cells constantly rub off.  Young inner cells constantly divide, producing new cells that replace old outer cells.

10.  In the epidermis of most fish are cells that produce mucus.  Mucus: A slippery material that helps the fish slide through the water.  The mucus constantly wears off.  As it wears off, the mucus carries away microscopic organisms and other irritants that might harm the fish.  Fish odor comes from the mucus.

11.  In the epidermis, fish have cells containing pigment grains.  Pigment grains give fish their color.  Some fish can change color by expanding or contracting pigment cells.  Changes are controlled by hormones produced by the endocrine system and regulated by the nervous system.

12.  The dermis contains blood vessels and connective tissue.  Blood vessels are nerves for sensing touch and vibration.

13.  A special layer of dermal cells constantly secretes chemicals to produce scales.  Scales grow larger as the fish grows.  As the scales grow, they form concentric rings which can be used to determine the fish’s age in some fish.  Most fish have covering scales that protect them from damage.  A few fish like catfish have no scales.

14. General Functions of the Skeletal System:  The skeletal system supports the soft tissues and organs of the fish.  The skeleton also protects organs and gives the body of the fish its basic shape.  Acts like levers in the body.

15.  The skeletal system consists of five parts: 1.Skull 2.Vertebrae or Backbone 3.Fin Supports 4.Spines 5.Rays

16. Skull: The many bones of the skull form a rigid box that protects the brain. Holes, hinges, and pockets in the skull allow room for the nostrils, mouth, and eyes.

17.  The vertebrae is a string of small bones.  Each vertebra has a small hole in it, forming a canal through which the spinal cord passes.  The bones around the holes protect the spinal cord.  Spaces between the vertebrae allow the nerves to reach the tissues and organs of the body.

18.  Fin Supports: Support the fin spines and rays.  Spines: Support the fins and protect the fish from predators.  Rays: Support the fins and help propel the fish through the water.