Download Simple Invertebrates

2/29/2012
Simple Invertebrates
Chapter 15, Section 1
6 Kingdom Review
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Archaebacteria
Eubacteria
Protist
Fungi
Plant
Animal
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Animal Characteristics
• To compare animals, look at:
– Type of body plan
– Presence or absence of a head (Nervous system)
• Nervous System - an organ system containing
specialized cells that coordinate the actions of an
animal and transmit signals between different parts of
its body
– The way food is digested and/or absorbed
(Digestive System)
• Digestive system – the organs/structures used to break
down food
• Invertebrates – an
animal without a
backbone
– Make up ~97% of all
animal species
• Examples:
– Clams
– Grasshoppers
– Earth worms
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Invertebrate Characteristics
• Body Plan:
– Invertebrates have 3 basic body plans
• Asymmetrical
• Bilateral symmetry
• Radial symmetry
Invertebrate Characteristics
– Symmetry - the identical reflection of two sides
• In order to be symmetrical, the right side of the pattern
or object is exactly the same as the left side of the
pattern or object.
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Body Plans
• Asymmetrical – without symmetry
– Example: sponges
Body Plans
• Bilateral symmetry – a body plan in which 2
halves of an organism’s body are mirror
images of each other
– Most animals have this
– 2 similar halves
– Examples: butterflies, crabs, dogs
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Body Plans
• Radial symmetry – a body plan in which the
parts of the body are arranged in a circle
around a central point
– Example: sea anemone, star fish, daisy
Invertebrate Nervous Systems
• Some have no brain or head
– No nervous system
• Some have fibers, called nerves
– Nerves – carry signals to control movements of an
organisms body
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Invertebrate Nervous Systems
• Simple invertebrates have nerves arranged in
networks or nerve cords throughout their
body
Invertebrate Nervous Systems
• Some invertebrates have ganglia
– Ganglia – groups of nerve cells
• Ganglia occur throughout the body and
control different body parts
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Invertebrate Nervous Systems
• More complex invertebrates have a brain and
head
– The brain controls the many different nerves in
different parts of the body
Invertebrate Digestive System
• Almost all animals (including invertebrates)
digest food in a central gut
– Gut – the pouch where food is digested in animals
– The gut is lined with cells that release powerful
enzymes
• Enzymes break food down into small particles that cells
can absorb
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Invertebrate Digestive System
• Some animals have a coelom
– Coelom – a cavity in the body of some animals
where the gut and organs are located
– It allows the gut to move food without
interference from the movements of the body
– Other organs (heart, lungs, etc.) may be in the
coelom
• Are separated from the gut
Groups of Invertebrates
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Sponges
• Originally thought to be plants
• Placed in the animal kingdom because:
– Can not make their own food
– Must eat other organisms
Sponge Characteristics
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The simplest animals
Invertebrates
Body plan = asymmetrical
No brain/head
No nerves
No gut
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Sponge Characteristics
• Can move, but are
very slow
• Live in water
– Most found in salt
water
• Have a skeleton
– made of spicules or
spongin
• Spicule – needle-like
splinters
• Spongin – a protein
– Supports the body of
the sponge
– Protects the sponge
from predetors
Kinds of Sponges
– Classified by the types of skelton that they have
– Bath sponges
• Skeleton is made of spongin
• Are soft
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Kinds of Sponges
– Silica sponges
• Made of silicate (the material we use to make glass)
• Largest class
• Skeleton made of spicules
Kinds of Sponges
– Calcium-carbonate sponges
• Spicules made of calcium-carbonate
• Calcium carbon is the material that makes the shells of
shellfish
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How Sponges Eat
• Sponges have tiny holes on the outside of
their body – pores
• Water is pumped into the sponge body
through pores
How Sponges Eat
• Special cells, collar cells, filter food particles
and microorganisms from the water
• The rest of the water flows into a central
cavity and out a hole in the top of the sponge
– the osculum
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Cnidarians
In phylum cnidaria – Greek word for “nettle”
More complex than sponges
All Cnidarians have stinging cells
3 classes
– Hydras
– Jellyfish
– Sea Anemones and corals
Cnidarian Body Plan
• Come in 2 forms:
– Medusa – looks like a mushroom
• Example: Jelly Fish
– Polyp – shaped like vases and usually attached to
a surface
• Example: Sea Anemone
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Cnidarian Body Plan
• Most Cnidarians spend
their life as a polyp
– Some are polyps and
medusas at different times
in their life
• What type of body plan
are these forms?
How Cnidarians Eat
• All cnidarians have long
tentacles covered with
special stinging cells
– another organism brushes
against the cnidarian
– 100’s of stinging cells fire
into the organism and
release a paralyzing toxin
• Each stinging cells uses
water pressure to fire a
nematocyst (a tiny barbed
spear)
– Cnidarian is able to ingest
their prey while it is
paralyzed
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Cnidarian Nervous System
• No Brain
• Have a nerve net
– A simple network of
cells
– Controls the
movements of the
body and the tentacles
• Medusas have a nerve
ring in the center of
its nerve net
– Coordinates the
swimming
Flat Worms
• Body Plan Bilateral
symmetry
• Are flat
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• 3 classes:
Flat Worms
– Planarians
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Have 2, large, unblinking eyespots
Small
Live on water and land
Digestive System –
– Eat other animals/parts of animals
– Digest food in a gut
• Nervous System –
– Clearly defined head with ganglia making up a primitive brain
» Nerves connect parallel nerve cords
– Have sensory lobes
» Bumps on each side of the head used for detecting food
Flat Worms
– Flukes and Tapeworms
• Parasites
• Most live and reproduce inside
the bodies of other animals
• Nervous System –
– Tiny heads without eyespots or
sensory lobes
• Digestive System –
– Have special suckers and hooks for
attaching to the host
– No gut
» Absorb nutrients from the
intestines of their host
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Round Worms
Aka - nematodes
Are round when viewed in cross section
Tiny, but long and slender
Bilateral symmetry
Most are parasites
Digestive System – break down dead tissues of
plants and animals
• Nervous System – simple
– A ring of ganglia forms a primitive brain
– Parallel nerve cords run the length of their body
Mollusks and Annelid Worms
Chapter 15, Section 2
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Circulatory System
• Circulatory system - an
organ system that passes
nutrients, gases,
hormones, blood cells,
etc. to and from cells in
the body
– Open circulatory system
– a simple heart pumps
blood thru spaces called
sinuses
– Closed circulatory system
– a heart circulates blood
thru a network of vessels
that forms a closed loop
Annelid Worms
• Aka – Segmented Worms
– Have segments
– Segments – identical, or almost identical repeating
body parts
• 3 classes:
– Earthworms
– Bristle worms
– Leeches
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Annelid Worms
• More complex than
flatworms and
roundworms
• Closed Circulatory System
• Digestive System - Have
coelom
• Nervous system– ganglia in each segment
– Brain in a head
– A nerve cord connects the
brain and the ganglia
Mollusks
• 2nd largest phylum of
animals
• Most live in the
ocean
– Some can live in
freshwater or on land
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• 3 classes:
Mollusks
– Gastropods (slugs and snails)
• Digestive system:
– have a ribbon-like tongue covered with teeth
» Teeth called radula
» Used to scrape algae off of rocks, chunks
of tissue from seaweed, or pieces of
leaves off of plants
• Open Circulatory System
• Nervous System – complex ganglia
Mollusks
– Bivalves (clams and other two-shelled shellfish)
• Digestive system – sit in 1 place and filter tiny plants,
bacteria and other particles from the water around
them
• Open Circulatory System
• Nervous System – complex ganglia
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Mollusks
– Cephalopods (squids
and octopuses)
• Digestive system – use
tentacles to grab their
prey and place it in
powerful jaws
• Closed Circulatory
System
• Nervous System – more
complex than other
mollusks
– Have a brain that
connects all of the
ganglia
– Smartest of the
invertebrates
Mollusks
• Share the same body parts
– Foot:
• broad and muscular
• Is used to move
– Visceral mass:
• Contains gills, guts, and other organs
• Located in the coelom
– Mantle:
• Layer of tissue that covers the visceral mass
• Protects mollusks that do not have a shell
See Figure 15 on
page 353
– Shell:
• Secreted by the outside of the mantle
• Protects the mollusk
• Keeps it from drying out
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