Download Station 1 THE STINGING CELLS Jellyfish, sea anemones, and

Station 1
THE STINGING CELLS
Jellyfish, sea anemones, and corals all have cells in the epidermis tissue layer of their tentacles called cnidocytes
(“stinging cells”). Coiled within these cnidocytes ready to be explosively launched are nematocysts (“stinging threads”).
When a mechanical or chemical stimulus reaches the cnidocyte, the cell opens, releasing the venomous nematocyst.
The animal can also coordinate the firing of many nematocysts at one time using nerve impulses. On average, the
animal loses 25% of its stinging cells with each capture or attack. Since the nematocysts are only used once, the
cnidarian regenerates the cells in about 48 hours.
There are three types of stinging threads in cnidarians. The first is called penetrating, because it actually enters the
victim’s skin and releases its toxin inside the animal. The second type of nematocyst is non-penetrating. This type of
stinging thread coils around and entangles its victim. The third kind of stinging cell is adhesive, sticking to the surface of
its victim. Almost all nematocysts have some type of barbs or hooks.
Station 2
PORTUGUESE MAN-OF-WAR
The Portuguese Man-of-War is called a Siphonophore. It is a member of Class Hydrozoa in Phylum Cnidaria. This
impressive animal is actually a colony of thousands of polyps and medusas. Various polyps in the Man-of-War form the
feeding tentacles with nematocysts, the “feeling” tentacles, and reproductive structures. The medusas in the animal
form the gas-filled lfoat, as well as the other reproductive structures.
The Man-of-War has a special gland within its float that secrete carbon monoxide (CO) gas. Some siphonophores (but
not the Man-of-War) can regulate the amount of gas in the float so they can sink below violent waves during a storm.
This cnidarian has a powerful sting that affects the nerve cells of its victim. In humans, the sting produces burning,
blistering, and muscle cramps. Incredibly, there are certain kinds of fish that appear to have a tolerance for the Man-ofWar’s toxin. These fish live unharmed within the jellyfish’s tentacles.
Station 3
SEA ANEMONE ANATOMY
The sea anemone is a member of Class Anthozoa in the Phylum Cnidaria. These animals are usually around 2-4 inches in
length, but can reach 1 meter in width!! The sea anemones are usually brightly colored, living in coastal waters attached
to rocks or other hard surfaces. They live in both warm and cool waters. Some sea anemones live attached to other
animals, such as crabs, in symbiotic relationship.
The sea anemone is one of the most complex cnidarians, with well-developed muscles and nerve cells. The base of the
anemone, where it attaches itself to a surface, is called the basal or pedal disc. The animal uses a mucus substance as
glue. The mouth is on top of the anemone, surrounded by tentacles. The mouth is slit shaped, with a ciliated groove at
each end called a siphonoglyph. The siphonoglyph helps circulate water into the anemone for support and gas
exchange. The mouth leads into the anemone’s pharynx or digestive chamber. The anemone has a thick mesoglea for
extra support since it does not have a hard skeleton.
Station 4
THE SEA ANEMONE
The sea anemone is a member of Class Anthozoa in Phylum Cnidaria. It lives in the polyp form, attached to a surface
with its tentacles pointing up. These cnidarians usually feed on fish or small invertebrates. Their prey becomes
paralyzed from the nematocyst’s toxin and caught in the tentacles. Then the anemone carries the food to its mouth
using the tentacles.
Sea anemones frequently form symbiotic relationships with small reef animals, such as cleaning shrimp, clown fish,
brittle stars, and snapping shrimp. Scientists believe that these animals coat themselves in the anemone’s mucus. The
tentacles then “recognize” the symbiotic animal as part of the anemone, and the animal does not get stung. Usually, the
reef animal benefits by eating the anemone’s leftovers. The anemone benefits because the reef animal acts as a decoy,
attracting other animals that the anemone will eat.
Station 5
THE CNIDARIAN COLLECTION
Station 6
SEXUAL REPRODUCTION IN CORALS
Coral gonads produce enormous amounts of eggs and sperm that are usually released directly into the water. After
fertilization, a free-swimming larva forms. The larva finds a hard surface to attach to. It then begins dividing to form a
colony. A coral is actually made of many polyps that are all divided from one original fertilized egg.
Coral spawning (releasing eggs and sperm) is sometimes synchronized with the tides to achieve a wide dispersal of their
offspring. Also, some coral species have an annual mass spawning, when the water literally fills with their eggs and
sperm. At this time, one can see a blanket of floating eggs and a musky odor fills the air.
Station 7
THE CORAL COLLECTION
Coral is a member of Class Anthozoa in the Phylum Cnidaria. These spectacular “flower animals” form the reefs along
tropical coasts around the world. The coral is actually a colony of tiny (1-3 mm) polyps. The reefs are formed by the
calcium carbonate (limestone—CaCO3) skeletons that the coral animals secrete. This skeleton serves two purposes for
the animal. First it provides a surface for the polyp to attach to. Second, the animal can withdraw into the limestone,
giving it plenty of protection. This skeleton is constantly being added to. The polyps are connected by a tissue that lays
over the hard surface.
Corals come in a great variety of shapes: branching, plate-like, flat, round, brain-like, and mushroom-like. The different
forms grow at different rates, with the branching growing the fastest. The coral polyps eat zooplankton and small fish,
feeding mostly at night.
Station 8
VARIOUS CORAL SAMPLES
A. Tongue coral—large polyp stony, has many mouths, with larger mouth around central furrow, short tentacles
(<2 cm) usually forked, active during the day.
B. Staghorn coral—can grow to 10 feet in height and 60 inches wide, yellow or purple, found around the
Caribbean.
C. Star coral—can grow to 60 inches wide, actively feeds on plankton, green or yellow-brown.
D. Brain coral—polyps are interconnected in rows making it look like a human brain.
E. Mushroom coral— solitary, does not live in colonies, can withdraw into ‘mushroom’ one polyp.
A
B
C
D
Station 9
THE BOX JELLYFISH AND THE LION’S MANE
Station 10
THE GORGONIANS
The members of the Order Gorgonacea in Class Anthozoa, Phylum Cnidaria include the pipe-organ coral and the sea fan.
These are very common along the coral reef. These flexible animals move with the water and look like plants. The sea
fan usually grows so that it is arranged at right angles to the water current.
Station 11
ZOOXANTHELLAE
Many cnidarians “farm” plants within their own tissues. By having zooxanthellae (photosynthetic cells) living
symbiotically in their bodies, they can directly benefit from the products of photosynthesis. Remember,
Coral animals that form the reef are especially in need of the zooxanthellae. These microorganisms provide materials
needed to make the limestone skeleton, as well as nutrition from the sugar byproducts of photosynthesis.
THE CNIDARIANS LAB
Station 1- The Stinging Cells
1.
2.
3.
4.
Examine the pictures of cnidocytes/ nematocysts. Draw and label both.
Define cnidocyte. ____________________________________________________________________________
Define nematocyst. __________________________________________________________________________
List three things that may cause the stinging cells to fire off. __________________________________________
___________________________________________________________________________________________
5. List the three kinds of nematocysts in cnidarians. ___________________________________________________
___________________________________________________________________________________________
Station 2- The Portuguese Man-of-War
6.
7.
8.
9.
10.
The Man-of-War is a _______________ in the Class ______________ in the Phylum ___________________.
Polyps in the Man-of-War form: _______________________________________
Medusas in the Man-of-War form: _____________________________________
_______________________ is the gas in the float of the Man-of-War.
List the effects of a Man-of-War sting on humans. ___________________________________________________
___________________________________________________________________________________________
Station 3- Sea Anemone Anatomy
11. Examine the sea anemone specimen. Locate and draw the mouth, pedal
disc, siphonoglyph, pharynx, and tentacles in the box to the right.
12. List three general characteristics of sea anemones. __________________
____________________________________________________________
13. How do you think a crab and a sea anemone could both benefit from their
symbiotic relationship? _________________________________________
____________________________________________________________
14. Why is water circulation necessary for the sea anemone? _____________________________________________
15. Why is the sea anemone’s mesoglea extra thick? ___________________________________________________
___________________________________________________________________________________________
Station 4- The Sea Anemone
16. Describe the steps in sea anemone feeding. ________________________________________________________
___________________________________________________________________________________________
17. Why aren’t the animals that live in the anemone stung by the tentacles? ________________________________
___________________________________________________________________________________________
18. How do the anemone and a small reef animal both benefit from a symbiotic relationship? _________________
___________________________________________________________________________________________
19. What type of symbiotic relationship is it when both organisms benefit? _________________________________
Station 5- The Cnidarian Collection
20. Examine the cnidarian collection compare and contrast in
the venn diagram to the right.
21. Cnidarians have __________ symmetry. All the
cnidarians have _____________ around their mouths.
22. Draw the horseshoe shaped reproductive structures on
the bell of the Aurelia jellyfish below.
23. Another name for gastrovascular cavity is __________.
polyp
medusa
Station 6- Sexual Reproduction in Corals
24. A coral is actually made of many ___________________ that are all ___________________.
25. Define spawning. _____________________________________________________________________________
26. List two ways coral animals try to improve their chances of successful reproduction. _______________________
___________________________________________________________________________________________
Station 7- The Coral Collection
27. The coral is actually a ____________________ of tiny _____________________.
28. Calcium carbonate is also called ___________________________ or _______________________________.
29. List the two functions of the coral skeleton. ________________________________________________________
___________________________________________________________________________________________
30. How are the polyps connected? _________________________________________________________________
31. List 5 different coral shapes. ____________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
32. List 3 types of corals in the specimen box. _________________________________________________________
___________________________________________________________________________________________
Station 8- Various Coral Samples
33. Examine the mushroom coral. The photograph on the information sheet shows a mushroom coral also. The
coral on the left has its tentacles withdrawn. The one on the right has them extended. How is the mushroom
coral different from most other corals we have studied? _____________________________________________
___________________________________________________________________________________________
34. The staghorn coral can grow up to __________ in height and is _________________ in color.
35. How are the polyps of the brain coral arranged? ____________________________________________________
Station 9- The Box Jellyfish and the Lion’s Mane
36. Examine the National Geographic article called “A Killer Down Under.”
a. P. 116- Contact with box jellyfish’s tentacles can bring death within ________ minutes.
b. P. 120- When fully grown, the box jellyfish may stretch _________ feet.
c. P. 122- They are about ________% water.
d. P. 122- Swimmer in Australian waters are urged to use only _______________ and to wear __________.
e. P. 130- The ___________________________________ snacks on the box jellyfish.
37. Examine the handbook’s photo and information about the lion’s mane jellyfish.
a. What is the size of the lion’s mane jellyfish? ____________________________
b. Where does this jellyfish live? _______________________________________________
Station 10- The Gorgonians
38. How is the sea fan different from the other types of coral we have studied? ______________________________
___________________________________________________________________________________________
39. Why do you think the sea fan usually grows at right angles to the direction of the water current? _____________
___________________________________________________________________________________________
Station 11- Zooxanthellae
40. Define zooxanthellae. _________________________________________________________________________
41. Write the chemical equation for photosynthesis. ____________________________________________________
42. What are two things that the zooxanthellae provide for reef-building coral animals? _______________________
___________________________________________________________________________________________
43. What benefit do you think the zooxanthellae receive from the coral animal? _____________________________
___________________________________________________________________________________________