Phylum Cnidaria

Question 1

what groups comprise the cnidarians?

Answer 1

1. hydrozoans
2. jellyfish
3. sea anemones
4. corals

Question 2

characteristics of cnidarians

Answer 2

• marine
• cylindrical bodies
• possess tentacles
• blind gut (single mouth/anus)
• first organisms with true tissues
• nerve net
• acoelomates
• swim by beating rows of cilia

Question 3

what kind of symmetry do cnidarians have?

Answer 3

radially symmetric

Question 4

how many tissue layers do cnidarians have?

Answer 4

2 (diploblastic)

endoderm, ectoderm

Question 5

what are the scyphozoa?

Answer 5

jellyfish (medusa stage)

Question 6

what are the anthozoa?

Answer 6

corals, anemones, sea pens, sea fans (polyps)

Question 7

what are the hydrozoa?

Answer 7

hydroids (polyps)

Question 8

polyp stage

Answer 8

sessile (attached to a substrate)
juvenile
cylindrical with tentacles
mouth directed upward

Question 9

medusa stage

Answer 9

adult, sexual
umbrella shaped free floating body type
mouth and tentacles pointed downward

Question 10

what makes sea anemones different from other cnidarians?

Answer 10

their mouth leads to a pharynx and then the gastrovascular cavity (purpose is ingestion)

Question 11

how do cnidarians catch prey?

Answer 11

tentacles around their mouth with stinging cells

-most cnidarians are carnivorous

Question 12

cnidocytes

Answer 12

specialized cells that release barbed nematocysts which sting and inject toxins into prey

Question 13

gastrovascular cavity

Answer 13

internal space in all cnidarians

• used for digestion
• only open at the mouth

Question 14

what are the two tissues of sponges?

Answer 14

epidermis and gastrodermis (middle is lined with mesoglea)