Invertebrates
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Transcript of Invertebrates
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Invertebrates
Chapter 2March/April, 2012
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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
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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
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Bilateral Symmetry
• 1. Bilateral symmetry– 2 similar halves– If you draw a line there
are 2 similar halves on each side
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Radial Symmetry
• 2. Radial symmetry– Body parts are
arranged in a circle around a central point
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Asymmetrical
• 3. Asymmetrical– No symmetry
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3 Types of Symmetry
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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
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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
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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
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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?
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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Roundworms
• 1. Have a simple nervous system and a primitive brain
• 2. Parasites• 3. Live in their host• 4. Pinworms and
hookworms infect humans!
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Mollusks and Annelid Worms
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Mollusks and Annelid Worms
• More complex than the invertebrates that we have studied so far
• Have a – 1. Coelom – 2. Circulatory system
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Mollusks• 1. Phylum: Mollusca• 2. Second largest
phylum of animals• 3. Includes
– Snails– Slugs– Clams– Oysters– Squid– Octopuses
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Mollusks• 3 Classes• 1. Gastropods (slugs and
snails)
• 2. Bivalves (clams and other two-shelled shellfish)
• 3. Cephalopods (squids and octopuses)
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Mollusks Characteristics
• 1. Most mollusks live in the ocean
• 2. Some live in fresh water
• 3. Soft body• 4.Usually covered by
a shell
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4 Main Parts of Mollusks
1.Foot- large muscle that mollusks use to move– Gastropods foot secrete mucus to help it slide
2.Visceral mass-contains gills, gut, and other organs in the coelom
3.Mantle- covers the visceral mass and protects the body of mollusks that don’t have a shell
4. Shell- protects the mollusks from predators and keeps them from drying out
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How do mollusks eat?
• 1. Clams and bivalves stay in one place and filter tiny plants, bacteria and other particles from the water
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How do mollusks eat?
• 2. Octopuses and squids use tentacles just like we use our fingers
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How do mollusks eat?
• 3. Snails and slugs eat with a tongue covered in curved teeth called radula
• 4. Slugs and snails use the radula to scrape algae off rocks, or pieces of leaves off plants
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Circulatory System
• Open circulatory system- simple heart pumps blood through blood vessels that empty into spaces in the animals body called sinuses
• Closed circulatory system- heart pumps blood through blood vessels that form a closed loop (cephalopods have closed system)
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Brain• Mollusks have complex
ganglia– 1. That control breathing– 2. Move the foot– 3. Control digestion
• Cephalopods have a more complex nervous system than any other mollusk
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Brain
• 3. Octopus can find their way through a maze, pick out different shapes and colors, and when given bricks or stones will build a cave to hide in……………… SCARY!!!!!!!!!
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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
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Annelid Worms (3 Classes)1st 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
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Bristle Worms
• 2nd Class is Bristle Worms• A. Come in many and bright colors• B. Live in water and burrow through sand
and mud to find food• C. Some crawl on the bottom and eat
mollusks and other small animals
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Leeches
• 3rd 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
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Bell Work
• 1. What are the 3 main classes of mollusks?
• 2. How do herbivorous snails and slugs use their radula to get food?
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Arthropods
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Arthropods
75% of all animals are arthropods
Characteristics of arthropods• 1. Jointed limbs• 2. Segmented body with specialized
parts• 3. Well-developed nervous system
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Jointed Limbs1. Jointed limbs gives
arthropods their names2. “Arthro” means joint3. “Pod” means foot4. Jointed limbs are arms,
legs, or other similar body parts
5. Jointed limbs let arthropods to move easily
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Segmented and Specialized
• 1. Most segments in arthropods are identical
• 2. Some segments include specialized parts such as– A. wings– B. antenna– C. gills– D. pincers– E. claws
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Segmented and Specialized
• 3. These specialized parts form during the animal’s development– A. head– B. thorax– C. abdomen
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Segmented and Specialized• 4. Exoskeleton- external
(outside) skeleton on arthropods made of protein and chitin
A. does the same thing as an internal skeleton
B. allows the animal to move
C. all muscles attach to the exoskeleton and move that part of the animal when the muscles contract
D. acts like a suit of armor to protect internal organs and muscles
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Segmented and Specialized
• 5. All arthropods have a head and a well developed brain
• 6. Some arthropods can detect light but can not form an image
• 7. Some arthropods can see images because they have compound eyes– Compound eyes- are made of identical light-
sensitive cells
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Kinds of Arthropods• 1. Arthropods are
classified according to the kinds of body parts they have
• 2. They are classified by their number of legs, and the antennae they have
• 3. Antennae- are the feelers that arthropods use for touch, taste, and smell
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Insects
• 1. Largest group of arthropod
• 2. Insects live everywhere EXCEPT the ocean
• 3.Insects are beneficial when they– A. pollinate
• 4. Insects are harmful when they– A. eat crops– B. carry diseases
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Insect Development
• Metamorphosis- the development of an insect from an egg to an adult
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Bell Work
• 1. Name 2 characteristics that classifies arthropods?
• 2. Can arthropods see?
• 3. What is an exoskeleton?
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Echinoderms
• 1. Phylum: Echinodermata echinoderm means “spiny skinned”– Includes star fish, sea urchins, sea
cucumbers, brittle stars, and sand dollars
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Echinoderms
• Characteristics• 1. Live on the sea floors• 2. Endoskeletons• 3. Echinoderm embryos form a mouth
like vertebrates when they first start to develop (this makes echinoderms more closely related to vertebrates than any other invertebrates)
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Echinoderms
• Characteristics• 4. simple nervous system that contains
nerve rings around the mouth and radial nerves that controls arms
• 5. water Vascular System- uses water pumps to help the animals move eat, breathe, and sense the environment
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The End! Invertebrates
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Test ReviewWords all 7th graders should know
about invertebrates!GangliaMedusaPolypOpen circulatory systemClosed circulatory
systemExoskeletonCoelumCollar cells
• Osculum• Characteristics of
Invertebrates• Porifera• Mollusca• Arthropods• Annelids• Cnidarians• Echinoderms