Lundkvist
Biology 11
PHYLUM CNIDARIA
Read pages 564-569 and answer the following questions.
1. What types of animals does Phylum Cnidaria include? Where do these animals live?
Jellyfish, sea anemones & corals. They live mostly in the sea.
2. What is a Cnidarian?
A soft bodied animal with stinging tentacles arranged in circles around
the mouth
3. What type of symmetry do Cnidarians exhibit? Radial symmetry
4. Some Cnidarians have a live cycle that includes two stages. What are these stages
called? Draw a picture of each life stage.
5. What is the gastrovascular cavity?
A cavity surrounded by a body wall where digestion takes place
6. What three layers does the body wall of a Cnidarian consist of?
Ectoderm, mesoglea and gastroderm
7. Write down everything there is to know about a nematocyst.
They are located in the tentacles
They are a poison filled sac with a spring loaded dart
When touched the dart uncoils and lands in the prey animal’s skin
8. Describe the symbiotic relationship that ensures that most Cnidarians do not have to
eat very much.
Tiny protists live inside the cells of the gastroderm. Photosynthetic
protists make O2 and food for the cnidarian and use metabolic wastes
of cnidarian
9. How do most colonial Cnidarians respire and eliminate waste?
By diffusion directly into the water
10. What is the nerve system called in Phylum Cnidaria? Nerve net
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Biology 11
11. Where is the nerve net located and what does it do exactly?
It is concentrated around the mouth but it is spread around the
entire body.
It allows cnidarians to move
12. What is the function of
a. statocysts? Balance- helps the animal stay upright
b. ocelli? Detect the presence of light
13. How do Cnidarians move even though they don’t have muscles?
Epidermal cells can change shape and act like muscles
14. Describe asexual reproduction in Phylum Cnidaria.
Budding- begins as a swelling on the side of the anemone that grows into a
complete polyp
15. What is a hermaphrodite? Have both male and female organs in the same
body
16. Complete the table below:
Class
Scyphozoa
Description
Both polyp & medusa stage
Branching sessile & colonial
True Jellyfish
Examples
Hydra
Portuguese man of war
Lion’s mane
Anthozoa
Only have a polyp stage
Sea Anemones
Corals
Hydrozoa
17. What is special about Portuguese man-of-war?
It forms floating colonies that contain several different kinds of polyps
18. Describe the largest Jellyfish ever found.
It was 3.6m in length with 30 cm long tentacles
19. To what class of Cnidaria do Corals belong? Anthozoa
20. Describe symbiotic relationships between sea anemonies and certain fish? How do
they both benefit?
2.
1.
Fish and shrimp are unaffected by
Nematocysts (Clown fish) They get
5.
Protection and in turn keep
anemonies clean
6.
4.
3.
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Biology 11
21. How are coral reefs important to humans?
They are homes for many food fish and they protect the shoreline.
22. Label the diagram: