1. Simple Invertebrates
Chapter 15.1

2. Invertebrate Characteristics
Invertebrates come in many shapes and sizes
Grasshoppers, clams, earthworms, and jellyfish are examples of invertebrates
They are all very different from each other.
Invertebrates have 3 different body plans or types of symmetry
Bilateral Symmetry
Radial Symmetry
Asymmetry

4. White Board Activity
Using a White board and your marker draw a picture to represent
Bilateral symmetry
Radial symmetry
Asymmetry
Share with your table groups when you are done

5. Neurons and Ganglia
All animals except sponges have special tissues that make fibers called neurons.
Neurons carry messages around the body to control an animal’s actions.
Simple invertebrates have neurons arranged in networks or nerve cords.
Nerve cords are packs of neurons that carry messages along a single path.

6. In some invertebrates many nerve cells come together as ganglia (singular, ganglion).
A ganglion is a concentrated mass of nerve cells.
Each ganglion controls different parts of the body.
Ganglion are connected by a nerve cord
In complex invertebrates, ganglia are controlled by a brain.

7. Guts Almost all animals digest food in a gut.
A gut is a pouch within cells that releases chemicals that break down food into small particles.
The cells in the gut then absorb the food particles .
In complex animals, the gut is inside the coelum, a coelum is the body cavity that surrounds the gut. The coelum contains many organs like the heart and lungs. This makes sure that the movement of the gut doesn’t disturb other organs

9. Sponges Sponges are the simplest invertebrates
They are asymmetrical and have no tissues, gut or neurons.
Adult sponges move only millimeters per day if they move at all.
The only reason sponges are classified as animals is because they are unable to make their own food.

10. How do sponges eat? Sponges feed on tiny plants and animals.
Because they cannot move they seep water into their bodies through their pores. This water brings oxygen and food into their body.
Pores are holes on the outside of the sponges body.
Special cells called collar cells line the cavity. They filter and digest the food.
Water leaves the body through the hole at the top called the osculum.

12. Sponge body part abilities
Sponges have some special abilities
If you forced a sponges body through a strainer, the separated cells could come back together again and form a new sponge.
If part of a sponge is broken off, the missing part can regenerate, or grow back.
Sponges reproduce through regeneration and also sexual reproduction
Kinds of sponges
All sponges live in water, most live in the ocean
Sponges come in many different shapes and sizes. Most sponges have spicules, which are fibers that make up the sponges skeleton.
1st period got here – 3rd period got part of the way through this slide

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15. Cnidarians
Cnidarians are a group of invertebrates that have stinging cells.
Jellyfish are members of this group
They are more complex than sponges. They have complex tissues and a gut for digesting food. They also have a simple nervous system
If a piece of cnidarian is broken off it can form a new cnidarian

16. There are 2 different body forms
The Medusa: this type will swim through the water
The Polyp: they usually attach to a surface.
All cnidarians have radial symmetry

17. Stinging Cells Kinds of cnidarians
All cnidarians have tentacles covered with stinging cells
When another organism presses against the stinging cells the cnidarian uses water pressure to fire tiny barbed spears from each cell.
Kinds of cnidarians
There are 3 major classes of cnidarians
Hydrozoans: spend most of their lives as polyps and live in both fresh and sea water
Jellyfish: catch their food in their tentacles and spend most of their lives as medusas
Sea anemone’s and corals: spend their lives as polyps and are often brightly colored

18. 2nd period got here.

19. Flat worms
There are many different kinds of worms, not all are round like an earthworm.
Flatworms are divided into three major classes
Planarians and marine flat worms
Flukes
Tapeworms
All flatworms have bilateral symmetry, most also have defined heads and 2 large eyespots

20. Some flatworms also have bumps on the side of their heads called sensory bumps
Planarians
Live in freshwater or on land in damp places
They eat other animals or parts of other animals and digest their food in their gut
Planarians use their sensory lobes to help find food and they even have a brain

21. Flukes
Are parasites
Most live and reproduce in the bodies of another animal.
Their fertilized eggs pass out of the body with the waste and are then ingested by other animals.
They have tiny heads without eye spots or lobes and use suckers and hooks to attach to the other animals.

22. Tapeworms Are similar to flukes
They have a small head, no eyespots or sensory lobes
They do not have a gut.
They attach to another organisms gut and absorb the nutrients from that organism

23. Roundworms Have bodies that are long, slim and round like spaghetti
The have bilateral symmetry
They also have a simple nervous system with a ring of ganglia making up their simple brain. Parallel nerve cords connect the 2 ends of their body
Most round worms are tiny, breaking down the dead tissue of plants and animals making the soil rich.
Some round worms are parasites like Trichinella spiralis.