Download invertebrates_th_grade

 Prefix –in means “not” or “without”
 Vertebra is one of the bones along the back of an
animal
 An INVERTEBRATE is an animal without a backbone
 Most animal species are invertebrates
 Skeleton – a structure in animals and humans that
provides mechanical support for muscle attachment
and maintaining body shape
 Although an invertebrate does not have a backbone,
it does have a skeleton
 It may have either an internal or external skeleton
made of minerals similar to limestone, glass,
protein, and even ordinary water
 1. About how many animal species are there?
 2. Why is a bee considered an invertebrate?
 3. Besides bone, list three substances that could
compose an animal's skeleton.
 Sponges are “pore animals”
 Their existence depends on the number of pores in
their bodies through which they pump water that
brings food and oxygen in and carries wastes out
 Phylum Porifera
 All sponges live in the water, and most live in oceans
 Adult sponges remain permanently attached to solid
objects and are unable to move place to place, BUT
embryonic sponges can swim around briefly
 Have skeletons made of spongin, of spicules, or of both
 Spongin - is a flexible, fibrous protein
 Spicules – stiff, pointed little spikes made of calcium
carbonate or silica
 Be familiar with Figure 15B-1 on page 269
 Collar cells – cells lining the central cavity, which
possess flagella
 Sponges are often called filter feeders because they
filter water to obtain food
 1. To what sponge characteristic does the name
Porifera refer?
 2. If adult sponges are permanently attached to solid
objects, how can they colonize other areas?
 3. What and how do sponges eat?
 Jellyfish belong to the phylum Cnidaria
 They have tentacles with stinging cells
 They are usually found in oceans; though a few can be
found in freshwater
 15C.1 The Body of a Jellyfish
The Jellyfish has a hydrostatic skeleton.
Has a large central cavity surrounded by two tissue layers.
Layers are called the ectoderm and the endoderm.
Inside the endoderm is the gastrovascular cavity were the
Jellyfish digests its food.
 The Jellyfish has no brain, just a network of nerves.
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15C.2 Jellyfish Activities
 The Jellyfish can defend itself and paralyze its prey with
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nematocysts (special cells found in the ectoderm).
The Jellyfish uses weak fiber muscle fibers in its tentacles to
push the prey into its gastrovascular cavity.
Digestive enzymes are released by cells in the endoderm to
break down the food in the gastrovascular cavity.
Jellyfish do not use their tentacles to swim. Most of the time
jellyfish just float.
When they do swim, a set of muscle fibers around the rim of
the jellyfish contracts.
15C.3 Other Interesting Cnidarians
 Hydras, corals, and sea anemones are also cnidarians.
 The Portuguese man-of-war is a dangerous cnidarian
that is actually a floating colony containing many
specialized polyps.
 The bodies of cnidarians have radial symmetry.
 Radial symmetry means that they can be divided into
equal halves by any plane along the length of the
organism.
 Cnidarians may be either free-floating or permanently
attached to a solid object.
1. What is the supporting material in a jellyfish's skeleton?
2. Where do jellyfish digest their prey?
3. What is the soft body of a coral animal called?
 Flatworm members = flat!
 Bilateral symmetry (can be divided into two equal
halves – like a mirror image)
 Phylum Platyhelminthes
 It is a free-living (not a parasite) flatworm that can be
found in freshwater streams and in soil.
 Flatworms can be found in the oceans, in fresh water
inside other animals as parasites, or in the soil.
15D.1 The Planarian’s Nervous System
 Neurons are long, thin nerve cells found throughout
the body of an animal or human.
 Most animals control their bodies through neurons.
 A collection of neurons wrapped in protective
coverings is called a nerve.
 Many invertebrates have nervous systems that are
fairly complex and require some coordination.
 An invertebrate’s “coordination center” is a ganglion,
sometimes called a simple brain.
15D.1 The Planarian’s Nervous System
 The planarian has a simple nervous system. A
longitudinal nerve runs down each side of its body.
 A series of transverse nerves connects the longitudinal
nerves.
 The planarian’s ganglia coordinate its responses to
stimuli.
 A stimulus is something an organism can sense.
 Planarians respond differently to different things such
as touch, the flow of water, chemicals in water, and
light.
15D.2 The Planarian’s Digestive and Excretory Systems.
 The planarian’s body covering is a tissue that is one celllayer thick.
 Cilia on the underside of the planarian help it glide over
underwater surfaces.
 The mouth of he planarian is on its underside, near the
middle of its body.
 Just inside the mouth is a long branching cavity called the
intestine which is lined with a layer of cells which is called
the gastroderm.
 The planarian eats by extending a muscular tube called the
pharanx through the mouth and sucking food into the
intestine.
15D.2 The Planarian’s Digestive and Excretory Systems.
 The planarian’s food is digested in the gastroderm.
 Nondigestible material is pushed out of the intestine
though the mouth.
 The planarian’s intestines extend to every area of the
worm’s body and food is moved throughout the intestine
by the twisting movements of the planarian and by flagella.
 The planarian has a mass of cells between its body covering
and gastroderm. Some of the cells are specialized for
particular functions.
 The planarian’s body is very thin. This allows the animal’s
cells to exchange oxygen and carbon dioxide directly with
the environment.
15D.2 The Planarian’s Digestive and Excretory Systems.
 The planarian gets rid of its waste products through a
system of tiny tubes.
 At the end of these tubes are structures called flame
cells. The cilia at the end of these structures look like
tiny flames.
 These cilia move water and wastes through the tubes
to tiny holes called excretory pores. Here the water and
wastes are excreted from the planarian.
15D.3 Other Interesting Flatworms
 Some other common flatworms include tapeworms,
flukes and marine flateworms.
 Tapeworms (a common parasite of animals and
humans) are found in the digestive tracts of various
animals.
 A Tapeworm has a head equipped with hooks and/or
suckers to attach it securely to the digestive tract. It is
nourished by absorbing dissolved food that is passing
through this digestive cavity.
1. What type of symmetry does a planarian have?
2. How many longitudinal nerves does a planarian have?
3. Where is the mouth of a planarian?
15E.1 Ascaris – A Common Roundworm
 In the phylum Nematoda
 Have round, tubular bodies and are tapered at each
end
 Some are serious parasites of humans, animals, and
plants; others are free-living
 Many are microscopic; some may grow to be 30cm
(12in) long!
 The adult Ascaris can be found in the intestines of
various animals
15E.1 Ascaris – A Common Roundworm
 The tiny eggs are swallowed and young larvae burrow
in the intestine walls and enter the blood stream
 They eventually reach the lungs and travel up the
throat and are reswallowed
 In the intestine again, larvae develop into adults
 Humans, cats, dogs, and various farm animals can
have round worms
15E.2 Other Interesting Roundworms
 Other serious roundworm parasites include
hookworms, pinworms, and trichina worms
 Trichina often form cysts containing larvae in the
muscle tissue of pigs
 Vinegar eel – appear as tiny threads in unpasteurized
vinegar and cider products (not parasitic thankfully!)
 Other roundworms cause serious plant diseases
1. Name the phylum that includes roundworms
2. Where does an adult Ascaris normally live?
3. Are roundworms parasites of animals only? Explain.
15F Segmented Worms
 The earthworm has a long, slender body made of a
series of similar segments
 The segmented body plan is what distinguishes
earthworms from others
 Phylum Annelida
 Leeches, tube worms, scale worms, sandworms, and
fireworms also belong to this group
15F.1 The Body of an Earthworm
 Covering the earthworm’s body is a thin, skin called an
epidermis
 The epidermis exchanges gases (carbon dioxide and
oxygen) with the environment.
 It also secretes a thin outer coating called the cuticle
 The cuticle protects the earthworm from harmful
parasites and substances
 Cuticle must be thin and its epidermis kept moist for
gas exchange
15F.1 The Body of an Earthworm
 Under the epidermis, are two muscle layers
 They provide support and help it move
 One layer is arranged in circles around the earthworm’s
body
 When these muscles contract, the worm becomes longer and
thinner
 The other muscle layer is arranged in long strips running
from the head to the tail
 When these muscles contract, the earthworm becomes
shorter and wider
15F.1 The Body of an Earthworm
 The earthworm moves by using its muscles and tiny
bristles on each segment
 It moves forward by extending the bristles on its rear
segments into the soil
 Once the rear segments are anchored, it contracts its
circular muscles – which causes it to become long and thin,
pushing its front end forward
 Then the worm releases the rear segments and extend the
front half into the soil, pulling itself forward by contracting
its long muscles
15F.2 The Earthworm’s Nervous System
 There are many sensory receptors on the body of the
earthworm
 Sensory receptor – a structure that can sense a stimulus
and then start an impulse traveling along a neuron
 Some of its sensory receptors are sensitive to chemicals in
the soil, others to light, and some to temperature and other
conditions
 There are more sensory receptors at an earthworm’s front
end because it leads with its front end
 They help the worm to sense whether it is approaching food or
danger so that it can react accordingly
15F.2 The Earthworm’s Nervous System
 The earthworm’s neurons carry impulses from the sensory
receptors in the front of the worm to two large ganglia in
the third segment
 Sensory receptors in other areas send impulses to the nerve
cord in the lower half of the worm
 Nerve cord – a bundle of neurons that begins at the two
large ganglia and continues to the tail of the worm
 Along the nerve cord there is one small ganglion in each
segment of the worm
15F.2 The Earthworm’s Nervous System
 The ganglia interpret the impulses from the sensory
receptors, and the worm decides what to do with them
 Interprets and decides describe the worm’s response to
stimuli – but these words are not good words because they
imply intelligence
 Earthworms have very little intelligence
 Neurons carry impulses to muscles, bristles, and other
structures that will enable the earthworm to respond
properly
15F.3 The Earthworm’s Digestive System
 often eats the soil as it forms tunnels
 Most of the soil is indigestible, but within the soil are
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decaying leaves, fungi, and small creatures
Has a long, straight digestive tract
At various points along the tract, there are enlargements,
constrictions, infoldings, and glands
Each has a separate function
The mouth secretes fluids that moisten the soil as it enters
Look closely: you may notice an upper lip! Used to force
food in their mouth
15F.3 The Earthworm’s Digestive System
 From the mouth, the soil passes to the pharynx
 Then to the esophagus – a tubular passageway that carries
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food from the pharynx to the crop
Crop – looks like a swelling in the digestive tract
Food leaving the crop passes into the gizzard – another
bulge in the digestive tract
Then it goes from the gizzard to the intestine
Indigestible parts pass through the intestine and leave the
digestive tract through the anus
Castings – wastes that accumulate in piles outside the
tunnels
15F.4 The Earthworm’s Circulatory System
 A continuous network of blood vessels
 Closed Circulatory System – when blood never leaves the
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blood vessels
Dorsal blood vessel – along the back – acts as a heart
It pumps blood forward to the five sets of aortic arches
Ventral blood vessel carries blood throughout worm
Capillaries – blood passes through arteries and enter tiny
blood vessels called capillaries
Blood flows from arteries through capillaries to veins
In closed systems, blood is carried toward the heart
15F.4 The Earthworm’s
Circulatory System
 Path of blood flow in a
closed circulatory
system:
 Veins heart 
arteries  capillaries
 Veins
15F.5 The Earthworm’s Respiratory and Excretory System
 Does not have special respiratory structures
 Gas exchange through the moist skin
 Excretory tubules – where wastes collect an are passed out
of the body through tiny pores
1. Name three members of phylum Annelida besides
earthworms
2. In which part of the earthworm's digestive system
does mechanical digestion occur
3. How does an earthworm breathe?
4. How can our study of earthworms help us exercise
dominion over the earth?
 Mollusks include the following animals:
 Clams
 Snails
 Slugs
 Octopuses
 Phylum Mollusca
 Phylum with the 2nd highest number of species and is
very important to the environment
 Also important to man
 Food (clams, oysters, and scallops)
 Make things (pearls, mother-of-pearl buttons)
 Pests or parasites (slugs and snails can be pests)
A Mollusk without a shell
 It’s body lacks structure to give
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it firm support
It does have many muscles
Eight arms (tentacles) that has
muscle to help it move its arms
in any direction
On the underside of each arm,
there are suction disks, which
allow it to grasp items.
Food captured in its arms can
be moved to its mouth (located
under the head)
 The suction disks can also be used to fasten itself to things
 If an arm is destroyed or severed, it has the ability to
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regenerate (grow) a replacement!
Although it hunts live food (crabs, lobsters, and shelled
mollusks), it appears to be a timid animal
If it senses danger, it hides
It moves by gliding along in the water – but it is a slow
creature
In order to move quickly, it forces water through a muscular
tube called a siphon
This jets the octopus through the water
Occasionally, when frightened, it will release an inky black
fluid into the water to serve as a “smoke screen”, allowing it to
get away.
 The octopus has a thin, flexible skin that helps its body hide
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more easily in the cracks between rocks and the ocean floor
It can “pour itself” into gaps and completely change its body
shape
It can also cause different colored cells on their skin to spread
out their pigments, helping to change colors!
It can become visible against almost any background
Its colors may also reflect its level of stimulation
If it is startled, it usually turns pale; when it is excited, it often
turns red
A Mollusk with a shell
 It produces a shell to
protect and cover their
bodies
 Clams, mussels, and
scallops produce two
shells hinged together –
called bivalves
 Snails and conchs produce
a single shell - called
univalves
 The clam’s soft body is covered with a thin skin called a
mantle
 Outside of this skin is where material is produced that
hardens to become a shell
 As it grows, it adds layers to the shell
 The newest part of the shell is thinnest
 It also has powerful muscles that keep its shell tightly
closed
 When a clam moves, it sends out a muscular FOOT
 It is hatchet shaped and is pushed into the sand and
expanded
 The muscles contract to shorten the foot and pull the
animal and shell forward
 They do not hunt for their food
 Clams are filter feeders
 They dig into the sand and send two tubes called
siphons out to the water.
 The siphon is used to draw water into the shell, where
tiny food particles are filtered out
 The other siphon sends the water away from the clam
to remove wastes
 1. Name a Mollusk that is edible
 2. What does an octopus use its siphon to do?
 3. What part of the clam's body manufactures its hard
shell?
 Phylum Arthropoda
 The most species of any animal phylum
 The insect class is the largest class within this phylum
 Almost a million species of insects identified
 Many play significant role in our world, especially insects
 They serve as:
 Pollinators, decomposers, crop eaters, disease carriers, and
parasites
 Animals in this phylum have:
 Exoskeletons, and jointed appendages such as legs and
antennae
 Exoskeleton – hard, nonliving, outer covering that supports
and protects the animal
 Insects typically have three sections to their bodies:
 Head
 Thorax (middle part)
 Abdomen
 They also have three pairs of legs (6 total)
 Caterpillars appear to have more than three pairs, but
actually they are not real legs
 Most insects have two pairs of wings, although some may
have none or one pair
 Compound eyes: their eyes have thousands of small
sections
 Grasshoppers see in a mosaic of smaller images
 See page 286 for picture
 Grasshoppers have blood and a circulatory system (like all
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arthropods)
Blood – is a fluid tissue made up of cells floating in liquid
The main function of blood – to carry substances to and
from all parts of the body
Heart – muscular organ that pumps blood to all body cells
Has a series of small tubular hearts located just under its
exoskeleton (see explanation p. 289)
Artery – blood vessels that carry blood AWAY from the
heart
Open Circulatory System – Blood that does not remain in
the blood vessels
 The blood is colorless, not red
 It carries mostly food and wastes and has little to do with
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oxygen transport
Tracheae – where insects receive oxygen and release carbon
dioxide
They are tiny elastic tubes that branch throughout the insect
Air is pumped in and out of these twenty small openings
called spiracles
Insecticides – chemicals only harmful to insects and not other
living things
As blood circulates, it collects wastes
These wastes are filtered out of the blood and collected by
thread-like excretory tubules
 Insects go through one of two different life cycles:
 Some molt throughout their life
 Molting – occurs when insects shed their old
exoskeletons and replace them with new ones
 This life cycle is called incomplete metamorphosis
 Metamorphosis – for insects mean, a change in body
form
 Incomplete Metamorphism:
 Start as eggs
 Go through a series of molts
 Developing stages called nymphs
 Then reach adulthood
 Example: grasshopper
 Complete Metamorphosis
 Involves 4 stages
 Egg
 Larva
 Most active stage
 Larvae of moths and butterflies known as
caterpillars
 Known for destructive appetites
 Other larvae – maggots (flies) and grubs (beetles)
 Pupa
 Resting stage where larvae uses food to change
body shape
 Cocoon (moth), chrysalis (butterfly), puparium
(flies)
 Each time one that undergoes COMPLETE
metamorphosis and molts, it passes into another
stage
 Most butterflies die soon after it has mated
 Butterflies do not become bigger butterflies
 Not all arthropods are insects
 Some are barnacles, crabs, lobsters, shrimp, pill bugs,
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centipedes, scorpions, and tarantulas
These differ from insects by the number of body segments
and appendages
Centipedes and millipedes are not worms
Centipedes
 Flattened
 One pair of legs per segment
 Poisonous claws to kill prey
Millipedes
 Somewhat rounded body
 Can have up to 100 body segments, and most segments
will have 2 pairs of legs
 They are not hunters like centipedes
 1. What are the three main parts of an insect's body?
 2. What type of eyes do insects have?
 3. What can we learn from an ant's behavior?
 4. List the four stages of metamorphosis
 5. List the three arthropods other than insects
 6. What sex are worker bees?
 Starfish – aka sea stars – are ocean dwelling animals
that, along with sea urchins, sand dollars, sea
cucumbers, and similar organisms are called
echinoderms
 Starfish are supported by a system of hard, flat plates just
under the skin
 Hard plates and spines provide protection
 Radial symmetry
 Arms are called rays
 They can regenerate or grow new rays if needed
 How do starfish move?
 Have a water-vascular system that is key to movement
 Noticeable part of system – rows of tiny tube feet on the bottom
of each ray
 Tube feet function like tiny suction cups
 They stretch out, attach, and then pull itself forward on hard
surfaces
 Favorite food of starfish – clams
 Climbs on top of a clam and uses tube feet to pull open shell (could
take hours)
 Then, turns its stomach inside out and pushed it throuh the
opening of the clam shell
 Digestive juices digest the soft part of the clam
 1. What is the function of the hard plates and spines in a
starfish?
 2. Where are a starfish's tube feet located?
 3. What does a starfish not need teeth?