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?