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CHAPTER 7
Animal classification
 Key science words
vertebrate
invertebrate
symmetry
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TRAITS OF ANIMALS
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Animals are consumers
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Must take in food from their surroundings
Some animals eat plants, others eat other
animals
Animals digest and store food in their
bodies
Most animals can move from place to
place
 Animals are multicellular organisms
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Cells are grouped into tissues and organs
that form systems
Most animals have a nervous, digestive,
and reproductive system
TWO GROUPS OF ANIMALS
Vertebrates
animals with backbones
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fish, amphibians, reptiles, birds
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Invertebrates
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animals without a backbone
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worms, and insects
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SYMMETRY
BALANCED ARRAINGEMENT OF BODY
PARTS AROUND A CENTER POINT OR
ALONG A CENTER LINE
 Two types of symmetry
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Radial
Bilateral
SYMMETRY
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Radial
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Body parts are arranged in a circle around
a central point
Ex. A sea anemone fig 7-1b
SYMMETRY
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Bilateral
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The body can be divided lengthwise into
two equal sides, a right side and a left side
This includes all vertebrates and some
invertebrates
The animal must have a head and a tail
end, and an upper and lower half
REVIEW OF TRAITS
1. Animals can’t make food, they must
catch it and eat it
 2. Most animals can move from place
to place
 3. Animals have many cells
 4. Most animals have some type of
symmetry
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9 MAJOR GROUPS
OF CLASSIFICATION
Sponges, stinging celled animals, 3
worm phyla, soft-bodied animals,
jointed-leg animals, spiny skinned
animals, chordates
 Sponges are the smallest phyla, jointedleg animals are the largest, refer to fig.
7-2
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SPONGES AND STINGINGCELLED ANIMALS
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Simple Invertebrates
Have pores
Do not move on their own
Live in salt and fresh water
Water comes in through the pores and out
through a hole at the top center of the body,
food from the water gets trapped by food
getting cells inside the body
SPONGES CONT.
Two cell layers thick
 Have no muscles or nerve cells
 No tissues, organs, or organ systems
 Reproduce sexually or asexually, by egg
and sperm, or by budding
 Sponges are asymmetrical lacking
symmetry

STINGING-CELLED ANIMALS
Animals with stinging cells
 Hollow sac-like bodies
 Lack organs
 Live in the ocean and in fresh water
 Examples: jellyfish, coral, sea fan
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Stinging-celled cont.
Have arm-like parts call tentacles that
surround the mouth
 Have RADIAL symmetry
 A body cavity contains an opening
called the mouth
 It’s the only way into and out of the
body
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Stinging-celled cont
Attach themselves to the ocean bottom
with or to rocks with a structure called
a disc
 Do not move from place to place
 How do they catch their food?
 With their tentacles
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WORMS
Worms are invertebrates
 3 phyla---flatworms, roundworms,
segmented worms
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We
Tentacles contain poison darts that
stuns the animal that touches them
 Food enters through the mouth and
undigested food leaves through the
mouth
 Reproduce sexually and asexually
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FLATWORMS
Simplest worms
 Flat body, 3 layers of cells, outer,
middle, and a thick middle layer
 Most flatworms are parasites
 Parasites live in or on other living things
getting food from them (called the
host)
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TAPEWORM
Flat ribbon-like body divided into
sections
 Live in the intestine of almost any kind
of vertebrate
 Have suckers and hooks that hold onto
the sides of the intestine
 They absorb food that has already been
digested
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TAPEWORM CONT.
Tapeworms in humans are not as
common as in other countries
 In the us waste is treated with
chemicals at sewage plants
 Meat is inspected for cysts
 However always cook your meat well
 Copy down the life-cycle of a tapeworm
into your notes pg 143
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ROUNDWORMS
Have long bodies with pointed ends
 3 layers of cells
 Some cannot be seen without a
microscope
 Many are parasites
 Hosts are people, dogs, cats, plants
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ROUNDWORMS CONT
Found in the soil
 Hookworms are parasites of people,
they enter through the skin of the feet,
once inside they move to the intestine,
and feed on the hosts blood
 Refer to figure 7-11
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ROUNDWORMS CONT
Have long rounded bodies
 Has a mouth and an anus (first animal
to have a 2 way gut)
 First animal to have an intestine
 Males and females are separate
animals, first animal to have separate
sexes
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SEGMENTED WORMS
Bodies divided into sections called
segments
 3 cell layers
 Most complex of the worms
 Live in salt water, fresh water and on
land
 Ex: leech, earthworm
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SEGMENTED WORMS CONT
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Segments have muscles
Have a mouth and an anus
Has an intestine
Two blood vessels
5 pairs of simple hearts that carry oxygen and
food to all the cells
Has nerves and a simple brain
Separate sexes
SOFT-BODIES ANIMALS
Soft body protected by a hard shell
 Body covered by a thin fleshy tissue
called a mantle (mantle makes the
shell)
 Have a muscular foot for moving
 Have a head with a mouth with teeth
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1st CLASS OF SOFT-BODIED
ANIMALS
Snails and slugs
 Live on land and in the water
 Glide using a muscular foot
 snails(shell) slugs(no shell)
 Snail has two tentacles (sense organs)
 Contain eyes that detect light
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2nd class
Clams, oysters, scallops
 Have two shells that fit together
 Have a muscular foot
 Live buried in the sand and filter water
to get food
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3rd class
Octopus, squid, cuttlefish
 Squid, cuttlefish have shells inside their
bodies
 Octopus has no shell
 Have tentacles surrounding the head
 Well developed eyes
 Rapid swimmers
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Features of soft-bodied
animals review
1 all are invertebrates
 2 soft body covered by a mantle
 3 most have 1 or 2 external shells, or
an internal shell
 4 most have a foot by which they move
about
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will consider the 9 phyla shown
below.