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Information obtained from: Holt Science and Technology: Life Science. Austin: Holt Rinehart & Winston, 2007. Print.
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Chapter 15 Section 1
Describe the body plans, nervous systems, and guts of invertebrates
Explain how sponges get food
Describe 3 cnidarian characteristics
Describe 3 kinds of flatworms
Describe the body of a roundworm
Coral is being used to speed up the growth of bone grafts (similar structure to human bone)
Some tapeworms can grow as long as a school bus!!
Make up about 96% of all animal species
1 million invertebrates have been named
No backbones!
3 basic body plans or types of symmetry
Nervous systems: Neurons & Ganglia
Guts
Bilateral symmetry 2 sides are mirror images
Radial symmetry Body is organized around a center Like spokes on a wheel
Asymmetrical Irregular, not organized around a center
Neurons allow animals to sense their environment
Neurons (fibers) carry messages around the body
Neurons are arranged in nerve cords (packs of neurons)
Ganglion: a concentrated mass of nerve cells
Each ganglion controls different parts of the body; connected by nerve cords
Controlled by the brain in complex organisms
Where digestion occurs
Pouch lined with cells that release chemicals that break down food
In complex organisms, the gut is inside a coelom (body cavity that surrounds the gut)
Keeps the gut from disturbing other body processes
Simplest invertebrates
Asymmetrical
No tissues, gut, or neurons
Barely move
Classified as animals
Feed on tiny plants and animals
Sweeps water into its pores, bringing in oxygen and food
Collar cells line the cavity and filter and digest food
Water leaves through the osculum
Separated cells can reform into a new sponge
Parts can regenerate (grow back) if broken off
New sponges can form from fragments
Regeneration is a form of reproduction (sexual reproduction is also possible)
Many shapes and sizes
Skeleton made of spicules (straight, curved, or star-shaped)
Skeleton offers protection from predators
Divided into groups based on shape
Jellyfish are members of this group with stinging cells
More complex than sponges Have a gut, simple network of nerve
cells, and complex tissuesMove more quickly than sponges
If broken off, parts can regenerate
Medusa Swim through water Can change forms over its lifetime
Polyp Attach to a surface Can change forms over its lifetime, some
are polyps only
Tentacles with stinging cells
Cells use water pressure to fire tiny barbed spears
Can release a painful, paralyzing poison
Used for protection and catching food
3 major classes:
Hydrozoans
Jellyfish
Sea anemones & corals
Hydrozoans Freshwater & marine environments Most of life as a polyp
Jellyfish Catch prey with tentacles Most if life as a medusa
Sea Anemones & Corals Most of life as polyps Brightly colored
Live in colonies
Build huge skeletons made of calcium carbonate (built over 1000’s of years)
Found in warm tropical waters around the world
The simplest worms
Divided into 3 major classes: Planarians & Marine Flatworms
Flukes
Tapeworms
Have bilateral symmetry
Clearly defined head
Two large eyespots
Can sense the direction of light
Bumps called: sensory lobes for detecting foodhttp://www.animalcorner.co.uk
Live in freshwater lakes & streams, or on damp ground surfaces
Predators
Digest food in a gut
Use sensory lobes to find food
Developed nervous system (have a brain)
http://georgiafaces.caes.uga.edu/graphicsfiles/LandPlanarian33lr.jpg
Parasites
Fertilized eggs can infect drinking water or food
Tiny heads without eyespots or flukes
Special suckers and hooks for attaching
http://upload.wikimedia.org/wikipedia/commons/2/28/Schistosome_Parasite_SEM.jpg
Similar to flukes
Small head, no eyespots or sensory lobes
No gut
Parasitic, attach to intestines and absorb nutrients; can infect humans
http://www.tripbase.com/articles/images/ThingsInsideYou/Tapeworm.jpg
Bodies like spaghetti
Bilateral symmetry
Simple nervous system
Very small
Decomposers; parasitic too
Infect humans: pinworms, hookworms
Disease: Trichinosis (from eating infected pork)
http://www.bioraynaturaldetox.com/uploads/images/roundworm.jpg
Describe the nervous system of most simple invertebrates
List 3 kinds of cnidarians
What is the relationship between a parasite and its host?