Basal Animals: Radiata: Phylum Cnidaria

Question 1

Phylum Cnidaria

Answer 1

The hydroids, jelly fish, sea anemones, corals

Question 2

Characteristics of Cnidarias

Answer 2

• Includes colonial hydroids, freshwater hydra, jellyfish, sea nettles, sea anemones, coral
• Radial symmetry
• “tissue” level of organization
• diploblastic construction- two “true” cell layers: epidermis and gastrodermis (what is mesolamella?)
• Gelatinous bodies
• Nematocysts- “ stinging cells”
• Body cavity and digestive cavity one and the same (no excretory system, no circulatory system.

Question 3

Classification of the cnidarias

Phylum Cnidaria

Answer 3

• Class hydrozoa- colonial hydroids, freshwater hydras
• class scyphozoa- “true” jellyfish
• class staurozoa- star jeliies
• class cuboza- box jellies, sea nettles
• class anthozoa- sea anemones, corals

Question 4

Class hydrozoa

Answer 4

• hydractinia”fuzzy” hydroid on hermit crab shell
• ## phylum cnidaria: class hydrozoa: the “hydroids”

Question 5

sexual reproduction in medusa:

“ Alteration of generations”

Answer 5

-First polyp- planula larva- fertilization- gametes- medusa

Obelia hydroid- colony of polyps

Question 6

Asexual reproduction in polyp colony:

“ Alteration of generation”

Answer 6

polyp colony- reproductive individual- medusa buds- medusae

obelia “jelly” medusa individual

Question 7

Hydra

Answer 7

” freshwater hydras”

green hydra- hydra viridis

Question 8

Book on freshwater hydra

Answer 8

Abraham trenbley’s 1744

Question 9

Physalia physalia

Answer 9

” Portuguese Man-of-war”

Question 10

Millepora complanata

Answer 10

” fire coral”

Question 11

Aurelia aurita

Answer 11

Moon jelly

Phylum Cnidaria: class scyphozoa- “true” jellyfish

Question 12

pelagia

Answer 12

” pelagie jelly”

Question 13

Phylum Cnidaria: Class staurozoa- star jellies

Answer 13

Craterolophus

Question 14

Phylum Cnidaria: Class Cubozoa: the “box jellies” and “sea nettles”

Answer 14

Chironex fleckerii “sea nettle”

Question 15

Phylum Cnidaria: Class Anthozoa

Answer 15

• All are polyps
• no medusae in the anthozoa
• polyps reproduce both asexually (by budding) and sexually (by making gametes)

Question 16

Darwin’s hypothesis- Subsidence of land

Answer 16

• coral reefs form around island
• reef grwo upward as land mass subsides
• lagon

Question 17

Testing darwin’s hypothesis

Answer 17

• they drilled to 1114 ft. and found only coral; considered results inconclusive

Question 18

symbotic relationship between reef-building corals and zooxanthellae

Answer 18

• mutualism- both organism benefit
• zooxanthellae provide coral with sugars and O2
• corals provide zooxanthellae with C02 and nitrogen
• coral with zooxanthellae deposit calcium carbonate 2- 3x faster than corals without

Question 19

Phylum Cnidaria: Class Anthozoa corals

Answer 19

• Elkhotn Coral
• Staghorn coral

Question 20

Phylum Ctenophora

Answer 20

• The comb jellies

Question 21

Characteristics of ctenophores

Answer 21

Similar to cnidarias
- Radial symmetry
- “Tissue” level of organization
- Diploblastic construction (two “true” cell layers)
- gelatinous bodies
Different from cnidarians:
- no nematocysts
- combs, eight rows arranged radially