Page 18 - Science Course 2 (Book 1)
P. 18
Mo1-L2a: What is an Invertebrate?
• Other invertebrates Cnidarians
hunt their food.
• Corals, anemones, jellyfish, hydras, and Portuguese
• Some invertebrates man-of-wars are members of phylum Cnidarian.
can even change the
color of their skin to
match their environments.
Key Concept
What is an invertebrate?
What characteristics do invertebrates have in • Cnidarians use special cells—called nematocysts—
common? to catch their prey by injecting poison into animals
that come in contact with them.
Flatworms
• Flatworms, in the phylum
Platyhelminthes, have a flat
body shape and bilateral
symmetry.
• Most flatworms live in
freshwater or salt water,
but some are parasites
and can infect humans.
Sponges
• Sponges, in the phylum Porifera,
live in water and attach to rocks
and other underwater structures.
Segmented Worms
• Sponges take in food when
water passes through their • Earthworms are segmented worms in phylum
bodies. Annelida.
• Setae are tiny, stiff hairs that
help earthworms grip surfaces.
• Each segment of an
Water Out Water In segmented worm is a
fluid-filled compartment,
therefore it has a
• Sponges have tiny, stiff fibers called spicules that hydrostatic skeleton.
support their bodies.
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