1. Define the following terms:
A. Amoebocytes – Cells within a sponge that produce its sketetal structure, perform digestion,
and repair cell damage.
B. Metamorphosis – A complete morphological change from larval to adult form.
C. Polyp – An attached cnidarian stage, appearing sac, like or barrel-like.
D. Medusa – A free-swimming cnidarian stage, appearing bell-like or umbrella-like.
E. Mesoglea – A jelly-like substance between the inner layer and outer layer of cells in a
cnidarian.
F. Mutualism –A relationship between two or more organisms of different species where both
benefit from the association.
G. Commensalism – A relationship between two or more organisms of different species where
one benefits and the other is neither harmed nor benefited.
H. Parasitism – A relationship between two or more organisms of different species where one
benefits and the other is harmed.
2. Give one example of each of a marine organism that exhibits (1) radial symmetry and
(2) bilateral symmetry.
Radial symmetry – Hydrozoans, corals, jellyfish, anemones, or comb jellies
Bitateral symmetry – flatworms, turbellarians, flukes, tapeworms, or any other worm in this
module
3. What are the two possible forms of support in sponges?
Spongin & Spicules
4. Despite the fact that polyps are generally stationary, cnidarians with only a polyp form
can spread to populate vast regions regions of the ocean. How do they accomplish this
without moving?
They produce planktonic larvae that float to new areas of the ocean.
5. Give at least 3 features common to cnidarians in both the polyp and medusa stages.
They both have (1) an oral side, (2) an aboral side, (3) a central mouth, (4) a mouth surrounded
by tentacles, (5) stinging nematocysts, and (6) a gut with a single opening.
6. Which of the 3 classes of phylum Cnidaria is composed of organisms spending most, if
not all, of their life cycle as a large medusa form: the Hydrozoa, the Scyphozoa, of the
Anthozoa?
The scyphozoan, or jellyfish.
7. A coral reef is a colony of anthozoan polyps. What part of it is actually alive?
Only the outside surface of a coral reef is actually alive.
8. An organism has a brain. It is most likely bilaterally symmetric or radially symmetric?
It is most likely bilaterally symmetric.
9. A worm has no gut. Of the worms we studied in this module, which kind is it?
It is a tapeworm.
10. Give an example of a parasite from this module.
Flukes, tapeworms, roundworms, & leeches
11. An organism is described as having a definite head and rear end; its long, thin body is
made up of a series of similar compartments; and it has a definite, fluid-like coelom. In
what phylum would you classify this animal?
Annelida
12. The lophophorates are grouped together because all the organisms have a
lophophore. What is this structure, and what does it do?
Crown of ciliated tentacles used for feeding.