Invertebrates Invertebrates Invertebrates 1 Animals without a backbone

Invertebrates

Invertebrates • Invertebrates – 1. Animals without a backbone – 2. Come in many different shapes and sizes • Can be compared by looking at: – 1. Type of body plan – 2. Whether or not the animal has a head – 3. The way food is digested

Body Plans • Invertebrates have 2 basic body types or types of symmetry – Definition of Symmetry • exact reflection of the form on opposite sides of a dividing line or plane

Bilateral Symmetry • 1. Bilateral symmetry – 2 similar halves – If you draw a line there are 2 similar halves on each side

Radial Symmetry • 2. Radial symmetry – Body parts are arranged in a circle around a central point

Asymmetrical • 3. Asymmetrical – No symmetry

3 Types of Symmetry

Presence or Absence of Head • 1. All animals except for sponges have nerves • 2. Nerves- carry signals to control movements of the body • 3. Simple invertebrates have nerves arranged in nerve cords throughout the body – These simple animals have no brain or head

Presence or Absence of Head • Some invertebrates have – A. Dozens of nerve cells that come together and are called GANGLIA – B. Ganglia • Are found throughout the body controlling different parts

Presence or Absence of Head • C. More complex animals have a brain and a head…………where the brain is stored • D. Brain controls many different nerves in different parts of the body

Bell Work • 1. What are nerves cells that help to control movement of different body parts? • 2. What is a part of the animal that is a pouch lined with cells that help break down food? • 3. What type of symmetry has 2 similar halves?

Don’t you have any guts? • 1. Almost all animals digest food in the central gut – A. Gut – Pouch lined with cells that break down food – B. These enzymes break down food in smaller particles so that cells can absorb them

Don’t you have any guts? • 2. Complex animals have a space in the body for the gut – A. called a coelom – B. Space in the bodies for the gut – C. Allows the gut to move food without interference from movements of the body – D. Other organs like the heart and lung are in the coelom but separated from the gut

Sponges • • Phylum: Porifera 1. Simplest animals 2. Asymmetrical 3. Regeneration- ability to replace itself. New sponges can form from pieces broken off another sponge • 4. If cells are separated, they can come back together and form a sponge

How do sponges eat? • 1. Water enters the sponge through its pores. Pore cells pump water into the sponge. • 2. Inside the sponge, cells called collar cells, filter food and microorganisms from the water • 3. Then the water flows into the central cavity and out the top of the sponge through a hole called a osculum

Cnidarians • Phylum: Cnidaria • 1. Cnidaria means “nettles” Nettles are plants that release stinging barbs in the skin • 2. More complex than a sponge • 3. Have complex tissues, a gut, and a nervous system • 4. In some of these species, if the cells are separated they can come back together like a sponge

Cnidarians • 5. Come in 2 forms – a. Medusa- looks like a mushroom with tentacles – b. Polyp- look like a vase and are usually attached to a surface

Cnidarians • 5. 3 classes • a. hydras- live in fresh water • b. jelly fish- usually have medusa form • c. anemones and corals usually have polyps forms

Cnidarians • “Catching Lunch” • 7. All cnidarians have long tentacles covered in stinging cells that catch small fish and other organisms by having these stinging cells that release paralyzing toxin

Cnidarians • 8. Cnidarians do not think • 9. They have a simple network of nerve cells called a nerve net that controls movement • 10. Medusa have a nerve ring that allows them to swim

Flatworms • 1. Simplest group of worms “Planarians” • 2. Bilateral symmetry • 3. Have a head and eye spots • 4. 2 sensory lobes on each side of its head used for finding food

Planarians • 5. Small- usually size of your fingernail • 6. Live in water and land • 7. Predators (eat on other animals or their parts) • 8. Has head, eyespots, sensory lobes and a small brain

Flukes and Tapeworms • 1. Parasites • 2. Live inside other animals bodies • 3. Host is usually killed • 4. Have heads without eyespots or sensory lobes • 5. No stomachs, they absorb nutrients of their host

Roundworms • 1. Have a simple nervous system and a primitive brain • 2. Parasites • 3. Live in their host • 4. Pinworms and hookworms infect humans!

Annelid Worms • Phylum: Annelida • Characteristics • 1. Segments- identical or almost identical repeating body parts • 2. Have a coelum • 3. Have a closed circulatory system • 4. Ganglia in each segment • 5. Brain found in the head and a nerve cord that connects the brain to the ganglia

Annelid Worms (3 Classes) 1 st Class are Earthworms • A. Most common are annelids • B. Some segments are specialized for eating and reproduction • C. Break down matter in the soil and excrete wastes called castings • D. When they burrow in soil, they allow water and air to reach deep in the soil • E. Stiff bristles on the outside of their body help them move

Bristle Worms • 2 nd Class is Bristle Worms • A. Come in many and bright colors • B. Live in water and burrow through sand mud to find food • C. Some crawl on the bottom and eat mollusks and other small animals

Leeches • 3 rd Class are leeches • A. Some are parasites and suck other animals’ blood, others eat dead animals • B. Doctors used to use them to “suck the bad blood” out of patients • C. Today some doctors use them to prevent swelling near a wound • D. Leeches also make a chemical that keeps blood from clotting

Bell Work • 1. What are the 3 main classes of mollusks? • 2. How do herbivorous snails and slugs use their radula to get food?

The End! Invertebrates