Invertebrates
copyright cmassengale
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Invertebrate Phyla
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Sponges
Cnidarians
Platyhelminthes
Nematodes
Mollusks
Annelids
Echinoderms
Arthropods
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Sponges (Porifera)
• Most primitive
• Cells relatively
independent
• Mostly marine
• No Symmetry
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Sponges
• No mouth,
stomachs, or other
organs
• Most live in oceans
• Cannot move
• They stink a lot
Cnidarians
• Mostly marine
• Radial Symmetry
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Cnidarians
• Jellyfish
• Hydra
• Coral
•Sea anemone
•Portuguese Man-O-War
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Invertebrates with
Stinging Cells
jellyfish
Sea anemone
• They have
tentacles
• They have a
mouth
• They live on
the ocean
floor
• They shoot
poisonous
darts
coral
Platyhelminthes
• Flatworms
• Bilateral symmetry
• Cephalization
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Planarian – freshwater
flatworm
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Nematodes
• Tube-like digestive
tract
• Roundworms!
• Mouth and anus
• No segmentation
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Worms
• They can grow back
parts if they lose
parts.
• Some worms can
grow to 30
METERS long
• An earthworm has
hairs on it to help
it go through the
dirt!!!
Flatworm
Roundworms
Segmented
Mollusks
• Clams, snails,
squids
• Varied habitats
– Marine
– Freshwater
– Terrestrial
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Invertebrates with
Soft Bodies
• They live on land
and fresh water
and ocean water.
• They make shells
from minerals in
the water
• Two shelled
mollusks has a big
foot to pull itself
along
octopus
snail
squid
Annelids
• Segmented worms
• Common earthworm
• Leech
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Echinoderms
• Always marine
• Starfishes, sea
urchins, sea lilies
• Spiny skin
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Invertebrates with
Spiny Skins
• They have bodies with at least 5
sections
• They have suction cup feet to
walk
• They use tubes to catch food to.
Brittle Star – An Echinoderm
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Arthropods
• Joint-legged
animals
• External skeleton
• Huge variation –
mostly insects
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Arthropods
There are 4 groups
Arthopods
• They have keen sense organs
• They have exoskeletons.
• They have two or more
segments
Crustaceans
• They have five
pairs of legs
• They live near or
on the ocean floor
• Live on land and
water
• They have antennae
Arachnids
• Spiders mites and
ticks.
• 4 pairs of legs
• Most live on land.
• Some live in fresh
water
• They are called
parasites.
Insects
• Largest group of
arthropods
• 3 pairs of legs
• 3 main body part
sections
• 2 pairs of eyes
• Have mouths
Millipedes & Centipedes
• Many body segments
• Live under rocks & dark
places
• Really have less than
100 legs
• Protects itself by
curling up
• Millipedes have 4 legs
on each segment
• Centipedes have 2 legs
on each segment
millipede
centipede
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