Phylum Cnidaria II

Question 1

Describe the feeding habits of Phylum Cnidaria

Answer 1

-All cnidarians are carnivores; they eat zooplankton and fish

-Tentacles are used for predation

Question 2

Describe the digestion of Phylum Cnidaria

Answer 2

-Intracellular and extracellular digestion

-Extracellular: GVC, absorption via cilia of cells, and enzyme breakdown

-Intracellular: Vacuoles store food, gastrodermal cells break it down.)

Question 3

What are the three major groups under Cnidarians? What’s the honorable mention fourth group that is not considered major?

Answer 3

Major:
1) Class hydrozoa
2) Class scyphozoa
3) Class cubozoa

Fourth group:
4) Subphylum Anthozoans

Question 4

What about the web-like system of synaptic connections is unique about cnidarians?

Answer 4

Impulses/ signals can be sent both ways across the synapses

Question 5

Describe class hydrozoa

Answer 5

-“water” animals
-small and plant-like
-Pelagic or immobile (attaches to substrate)
-Mostly marine

KNOW:
-POLYP is the dominant form
-GVC is continuous in a colony, after budding, colonies remain attached.

Question 6

What are the morphotypes of class hydrozoa?

Answer 6

-Gastrozoids: feeding/ digestion morph

-Gonozoids: repro morph; relies on gastrozoids

-Dactylozoids: defense (cnidae)

Question 7

How do class hydrozoa reproduce

Answer 7

-medusae are produced (can be released or retained.)
-Gonads released
-Offspring are called planula larva

Question 8

What are hydromedusae?

Answer 8

-Sexual stage
-Possess velum
-Possess manubrium

Question 9

What is the velum?

Answer 9

-Used for propulsion
-Is the margin surrounding the mouth, within the margin of the bell

Question 10

What are some characteristics of Ctenophora?

Answer 10

– ”Comb” bearing
– Highly ciliated
* Plates of fused cilia (ctene)
* Arranged in “comb” rows
– Possess colloblasts
* Prey-capturing cells
* Like “sticky” nematocysts
– Diploblastic
* Ectoderm/epiderm
* Gastroderm
* Mesoglea
* Muscles lie within mesoglea
– One-way digestion
Exclusively marine
– ~150 species
– All planktonic (1 parasitic)
– Predatory
– Bioluminescent

Question 11

What is the manubrium?

Answer 11

A stalk-like structure that hangs from the center of the mouth and functions as the anus.

Question 12

What are octocorillia

Answer 12

subclass in anthozoa
Many tentacles around mouth
* Multiples of 8
* Pinnate
– Numerous lateral outfoldings
– Pinnules
* Mesenteries in 8 too
* One siphonoglyph
– Many produce sclerites
– Almost all are colonial

Question 13

What are hexacorillia

Answer 13

subclass in anthozoa
– Many tentacles around mouth
* Multiples of six
* Non-pinnate
* Mesenteries in sixes too
* Two siphonoglyphs
– Defense tentacles
* Acrorhagi
– Stubby tentacles
– Near mouth, under main tentacles
* Acontia
– Long, thin filaments
– At base of column
– Ejected through pores

Question 14

Diversity of the hydrozoa: list some critters from class hydrozoa

Answer 14

1) Portuguese man-of-war
2) Wind-by-the-sailor
3) Siphonophore

Question 15

Describe class scyphozoa

Answer 15

• “true jellyfish”
• “cup” animals
• 200 marine species

KNOW:
- Medusa form is dominant
- Non-colonial

Question 16

Describe sexual reproduction in anthozoa

Answer 16

Sexual
– Mass spawning
– Internal fertilization
– Produce planula larvae

Question 17

Describe asexual reproduction in anthozoa

Answer 17

• Asexual
  – Fission – divides in half
  – Budding – produces new polyps for growth
  – Pedal laceration – piece pedal disc detaches
  – Fragmentation – piece of colony breaks off

Question 18

Define characteristics of anthozoa

Answer 18

– “Flower” animals
– Large array of tentacles
– Largest group (~ 6000 sp.)
– Polyp stage only
* No medusa
* Solitary or colonial
– Circular mitochondrial DNA
* Same as most eukaryotes
* All other Cnidarians are linear
– Often brightly colored
– Typically shallow, but also in deep sea
– Two subclasses
* Hexacorallia
* Octocoralli

Question 19

What is the morphology of anthozoa

Answer 19

– Body supported by thick column
– Mouth
* Surrounded by tentacles (oral disk)
* Leads to pharynx
* Contains ciliated grooves
– Siphonoglyphs
– Beating cilia bring water into GVC
– Maintains water pressure/hydrostatic
skeleton
* Width & height controlled by circular
& longitudinal muscles

Question 21

Describe the scyphomedusa form

Answer 21

• Posses manubrium
• Filly oral arms with cnidae
• 4 gastric pouches that branch off from the stomach; canals lead to edges of the bell

Question 22

Describe the reproductive habits of class syphonomedusa

Answer 22

• Gonochoristic: (2 sexes), female or male medusae

Question 22

List the steps of scyphozoan reproduction

Answer 22

1) Fertilized zygote
2) Planula larvae
3) Scyphistoma (polyp)
4) Strobilation (budding)
5) Ephyra (baby jellies)

Question 23

Describe class cubozoa

Answer 23

• “cube” animals
• About 20 marine species
• Can be hella poisonous
• Active predators
• Box jellies

KNOW:
- Medusa form dominant
- Non-colonial

Question 23

Do box jellies strobilate?

Answer 23

No