Kingdom Animalia: Phylum Cnidaria

Question 1

What are the 3 major classes of the Phylum Cnidaria and what types of organisms do they contain?

Answer 1

1. Anthozoa: true coral, sea anemones, sea pens ~ 6000 spp
2. Hydrozoa: Hydroids, freshwater hydra, fire coral ~ 3000 spp
3. Scyphozoa: true jellyfish ~ 200 spp

Question 2

Most cnidarians are_________, but some live in __________

Answer 2

Marine

Freshwater

Question 3

How is the body plan of a cnidarians structured?

Answer 3

have body plan with RADIAL SYMMETRY

Question 4

What are Cnidaria the first phylum to have?

Answer 4

have TRUE gastrovascular cavity (gut)

Question 5

How many openings are there to the gastrovascular cavity and what does it function as?

Answer 5

1
function as mouth and anus

Question 6

Like the sponges they only have 2 germ layers what are they?

Answer 6

1. Epidermis: outside

2. Gastroderms: inside

Question 7

What is a Mesoglea?

Answer 7

Not really a germ layer

A jelly-like material that lies between the EPIDERMIS and the GASTRODERMIS

Question 8

What do Cnidaria not have?

Answer 8

DO NOT HAVE ORGANS but HAVE tissue level organization

Question 9

What does polymorphism mean?

Answer 9

MOST Cnidarians have life cycles that include two distinct stages:

1. Polyp
2. Medusa

Question 10

What does Polyp mean?

Answer 10

sessile, flower like, anchored-mouth up

Question 11

What does Medusa mean?

Answer 11

motile, bell shaped, free floating-mouth down

Question 12

How do Cnidarians capture food?

Answer 12

tentacles

Question 13

What are the thousands of specialized cells on the tentacles called?

Answer 13

Cnidocytes

Question 14

Cnidocytes each contain an organelle called a…

Answer 14

nematocyst

Question 15

What does each nematocyst contain?

Answer 15

Coiled, hollow, threadlike tube which is often filled with poison

Question 16

What happens when an animal brushes against its tentacles?

Answer 16

triggers the nematocysts to fire harpoon like threads in order to TRAP, PARALYZE and sometimes KILL the prey

Question 17

What does it mean by the Polyp form is sessile?

Answer 17

it must wait for the prey to come close enough to capture it

Question 18

What does it mean by the Medusa form is motile?

Answer 18

it can accidentally swim close enough to the prey to capture it (don’t have a brain to think about what it is doing)

Question 19

Where is the captured prey brought to?

Answer 19

brought to MOUTH/ ANUS with tentacles where it is digested

Question 20

Where are the nutrients from the prey digested into and how where do they diffuse it?

Answer 20

digested prey absorb into the GASTRODERMIS and diffuses throughout the CNIDARIAN

Question 21

What do some cnidarian rely on?

Answer 21

symbiotic photosynthetic protists and must live in sunlight

Question 22

How is oxygen absorbed?

Answer 22

Oxygen absorbed directly into cells of cnidarians from surrounding water by diffusion

Question 23

How is carbon dioxide release?

Answer 23

Carbon dioxide released directly from the cells of cnidarians into the surrounding water by diffusion

Question 24

How is undigested food release back into the water?

Answer 24

through the MOUTH/ ANUS

Question 25

How are metabolic waste released back into the water?

Answer 25

directly from the cells of Cnidarians into surrounding waters

Question 26

Cnidarians DO NOT have a _____ but they have a _______ that encircles the body

Answer 26

brain

nerve net

Question 27

They have specialized sensory cells that detect what 3 things?

Answer 27

1. Chemicals
2. Touch
3. Light

Question 28

How do cnidarians reproduce?

Answer 28

1. asexual (budding)

2. Sexual (releasing gametes)

Question 29

What is the life cycle steps of a planula larvae?

Answer 29

1. zygote grows into free swimming cilated larva

2 settles, attaches and changes into a polyp to begin life cycle again

Question 30

How do cnidarians move?

Answer 30

1. lack true muscle cells but epidermal cells can change shape with nerve impulses
2. Medusae move through jet propulsion

Question 31

5 things about the class Hydrozoa

Answer 31

1. Spend most of life as polyps with short medusa stage
2. most exist as branching, sessile colonies
3. Reproductive polyps produce free swimming medusa that produce both egg and sperm and then die
4. Most common freshwater hydrozoans are the hydras that can reproduce both sexually and asexually
5. Some hydra are hermaphroditic (both male/female) while most exists as separate sexes

Question 32

Fact about the class Scyphozoa (true jelly fish)

Answer 32

1. Go though same stages as Hydrozoans but polyp stage is short lived while medusa stage is long lived

Question 33

4 things about the class anthozoa

Answer 33

1. have only polyp stage in life cycles
2. sea anemones exists as solitary polyps, while corals exists mostly in colonies
3. corals: polyps secrete calcium carbonate and build up into huge coral reefs. They form important habtat for other plants and animals