Worms, Cnidarians,
and Sponges
Review Sheet Answers
Sponges #1
What is an invertebrate?
Invertebrates are animals that do
not have backbones.
Sponges #2
What does asymmetrical mean?
It has no symmetry.
Sponges #3
Define sessile.
An organism spends its life
attached to one spot and does
not move from place to place.
Sponges #4
What are pores? How do
they help sponges?
Small openings that surround
the entire body of a sponge.
They allow water and oxygen to
enter the sponge’s body.
Sponges #5
How do sponges obtain food
and oxygen?
Water travels through the pores
and it carries food and contains
oxygen molecules. The
specialized cells filter them out.
Sponges #6
Do sponges have tissues, cells,
or organs?
CELLS!!
Sponges #7
What are spikes? How do they
help sponges?
They form a rigid frame that helps
support the sponge’s body. They
also are a defense mechanism.
Sponges #8
Describe the two types of
reproduction.
Asexually: Budding. Buds form on
the parent sponge and eventually
break off and float away.
Sexually: Fertilization. Sperm are
released by a male sponge and then
fertilize a female’s eggs.
Sponges #9
What is a larva?
A fertilized egg becomes a
larva. It is the immature form
of the adult and looks very
different.
Cnidarians #10
What is radial symmetry?
Many lines of symmetry, all
through a center point.
Cnidarians #11
How are cnidarians’ tentacles
unique?
They have stinging cells.
Cnidarians #12
What is a nematocyst?
A capsule in the stinging cell
that holds a barbed filament.
Cnidarians #13
Cnidarians are more advanced
than sponges because they
have….
TISSUES!
Cnidarians # 14
Describe the two types of
reproduction of cnidarians.
Asexual – Budding (buds form on
the adult, break off, float away, and
then attach to the ocean floor).
Sexual – Sperm are carried to the egg
where fertilization occurs.
Cnidarians # 15
What is a polyp?
Vase-like shape.
Mouth is on the top.
Sessile
What is a medusa?
Free swimming animal.
Mouth is on the bottom.
Looks like an upside down bowl.
Worms #1
What are the 3 types of worms?
Flatworms: they are FLAT
Roundworms: they are
ROUND
Segmented worms: they have
SEGMENTS
Worms #2
What is bilateral symmetry?
Only one line of symmetry in
the animal.
Worms #3
What is regeneration?
The ability to regrow body
parts.
Worms #4
What is a parasite?
Organism that lives on or in
another organism.
Worms #5
What is an eyespot?
Allow the organism to see light
versus dark.
Planaria have them.
Worms #6
What are odor cells?
Allows the organism to smell
food.
Planaria have them.
Worms #7
How do planaria eat?
They insert feeding tubes into
the food.
Next, digestive juices start to
digest the food outside the worm.
Finally, the feeding tubes bring
the prey into the worm.
Worms #8
Where do most roundworms
live?
Moist environments
Worms #9
What type of digestive tract do
roundworms have?
Open at both ends or one way.
Worms #10
What are segments?
Tiny linked sections that cover
the worm’s body.
Worms #11
Describe the digestive tract of
segmented worms.
Open @ both ends – One
Way.
Worms #12
Describe a closed circulatory system.
What is it and why do some animals
have it?
Blood moves through a
connected network of blood
vessels.
It is important because it allows
animals to grow larger.
Worms #13
What does it mean that
earthworms are scavengers?
They eat decayed plant and
animal remains in soil.
Worms #14
Why do earthworms need
moisture?
They get oxygen from the
water that’s on their skin.
No moisture = no oxygen.
Worms #15
How do earthworms help
gardeners and farmers?
Tunnels loosen soil and
provide room for air, water,
and roots, which promote
plant growth.