Deck 13: Cnidarians and Ctenophores

Question 1

The traditional view of cnidarians relative to germ layers is that cnidaria possess

A)only one germ layer,the ectoderm,that differentiates into the two tissue layers.
B)two germ layers,ectoderm and mesoderm.
C)two germ layers,endoderm and mesoderm.
D)two germ layers,ectoderm and endoderm.
E)definitely all three germ layers including the mesoglea as it is derived from ectoderm.

Answer 1

D

Question 2

The presence of amoeboid cells and fibers in the mesoglea,as well as lack of a velum,would indicate that a medusa was in the class

A)hydrozoa.
B)scyphozoa.
C)anthozoa.
D)ctenophora.
E)cubozoa.

Answer 2

A

Question 3

A hydra moves by

A)nematocysts.
B)expelling water from the gastrovascular cavity.
C)contraction of the nerve net.
D)epitheliomuscular cells in the epidermis.
E)epitheliomuscular fibers in the mesoglea.

Answer 3

D

Question 4

Which of the following is NOT a correct association?

A)Nematocyst-stinging organelle
B)Operculum-lid covering the capsule containing the coiled thread
C)Cnidoblast-a developing cnidocyte
D)Cnidocil-poison gland
E)Hydrostatic pressure-pressure inside capsule that forces the nematocyst out

Question 5

The Portuguese man-of-war has long tentacles with many nematocysts.These tentacles are called

A)dactylozooids.
B)gastrozooids.
C)gonophores.
D)pneumatophores.
E)colloblasts.

Question 6

Which of the following is NOT a correct description of cnidarian nervous tissues?

A)Hydrozoan medusae have ring nerves
B)Scyphozoan medusae have marginal sense organs
C)The nerve net synapses with both the nematocysts and the epitheliomuscular cells
D)Scyphozoa have both a fast conducting and a slow conducting system to coordinate movements
E)Cnidaria are the first animals to develop a central nervous system

Question 7

Throughout most cnidarian groups,the basal or pedal disc serves to

A)be the base of the tentacles.
B)attach the cnidarian to the substrate.
C)generate buds.
D)perform extracellular digestion.
E)harbor sensory cells.

Question 8

The _____ stage is best adapted for cnidarians living in colonies while the ____ stage helps in dispersal and survival in open oceans.

A)gastrozooid,dactylozooid
B)lappet,rhopalium
C)medusa,polyp
D)polyp,medusa
E)dactylozooid,gastrozooid

Question 9

Digestion in hydra is

A)intracellular only.
B)extracellular only.
C)both extracellular and intracellular.
D)neither extracellular nor intracellular.
E)none of the choices is correct.

Question 10

The term "cnidaria" is based on the root words meaning

A)stuck in one place.
B)middle glue.
C)little spear.
D)thread bladder.
E)like nettles.

Question 11

Which of the following is NOT a cnidarian?

A)Corals
B)Planaria
C)Sea anemones
D)Hydrozoa
E)Portuguese man-of-war

Question 12

The class of radiate animals with the most conspicuous medusa stage is

A)hydrozoa.
B)scyphozoa.
C)anthozoa.
D)ctenophora.
E)cubozoa.

Question 13

The unique feature(s)of a cnidarian nervous system is/are

A)vesicles with neurotransmitters located on both sides of the synapse.
B)nerve impulses are transmitted in both directions across a network of nerves.
C)cnidarian nerves lack any myelin surrounding the axons.
D)All of the choices are correct
E)None of the choices is correct

Question 14

Nematocysts are expelled when the

A)osmotic pressure reaches 140 atmospheres.
B)hydrostatic pressure exceeds the osmotic pressure.
C)internal hydrostatic pressure increases when water enters.
D)cnidocil stimulates the cnidocyte to decrease hydrostatic pressure and increase osmotic pressure.
E)None of the choices is correct

Question 15

How does Hydra reproduce sexually?

A)Separate male polyps and female polyps produce sperm and eggs,respectively,that fuse and grow into a medusa
B)The swimming medusa stages are male and female and the fertilized eggs develop into planula larvae that become Hydra polyps
C)The polyp body wall can produce both ovaries and testes that make eggs and sperm respectively
D)Hydra sperm fertilize an egg in the body wall and this starts the growth of a bud
E)Hydra do not reproduce sexually since they lost the sexual medusa stage

Question 16

The class Hydrozoa contains Hydra,Obelia,and

A)the Portuguese man-of-war.
B)aurelia.
C)the sea anemones.
D)most of the corals.
E)None of the choices is correct

Question 17

Cnidarians are found most abundantly in which of the following habitats?

A)Shallow marine habitats
B)Freshwater habitats
C)Deep ocean habitats
D)Estuary habitats
E)None of the choices is correct

Question 18

Nematocysts are

A)widespread among the animal kingdom but first developed by Cnidaria.
B)formed and used only by Cnidaria although a few other organisms may "steal" them.
C)first found in sponges,most highly developed in cnidarians,but still found as remnants in some higher groups.
D)actually free-living symbionts that are most usually taken up by cnidarians,as are many green algae.
E)None of the choices is correct

Question 19

Hydra reproduces asexually by

A)buds.
B)nematocysts.
C)gland cells.
D)gametes.
E)gastrozooids.

Question 20

The fossil record of Cnidaria is

A)about the same as for other primitive animals,beginning in the Cambrian.
B)relatively sparse since their bodies are so soft that they leave no skeleton to fossilize.
C)one of the longest records,with fossils going back over 700 million years.
D)sporadic since the marine environment is not a good substrate to preserve fossils.
E)very recent since most of them have symbiotic relationships with advanced animals such as clown fish.

Question 21

Which association of anthozoan traits is NOT correct?

A)Hexamerous-parts in multiples of six
B)Octomerous-parts in multiples of eight
C)Coupled-septa matched across gastrovascular cavity
D)Hydrostatic skeleton-hard coral secretions
E)Pedal laceration-small pieces break off and regenerate new anemones

Question 22

The morphological type of cnidarian adapted to a sedentary or sessile life is the polyp,and the type best adapted for floating or free-swimming existence is the ___________.

Question 23

To help overcome prey,some sea anemones have ____________ with nematocysts and gland cells that protrude through the mouth or pores.

A)acontia threads
B)siphonoglyphs
C)pedal lacerations
D)strobila
E)pneumatophores

Question 24

The body wall of a hydra consists of an outer epidermis and an inner gastrodermis with _______________ between them.

Question 25

A pharynx and mesenteries are structures found in

A)hydra.
B)sea anemones.
C)aurelia.
D)obelia.
E)cubozoans.

Question 26

A/An ____________________ encircles a lagoon but there is no central island.

A)atoll
B)barrier reef
C)bank or patch reef
D)fringing reef
E)reef crest

Question 27

A living anemone must detect non-living debris that floats by from potential food that also move past it.How does it detect the difference?

A)It responds to anything with DNA as living
B)It has a feeding response to certain chemicals such as glutathione and asparagine
C)They respond to vibrations that match the frequency of prey
D)There is a feeding response to certain chemicals such as glutathione and asparagine;additionally they respond to vibrations that match the frequency of prey
E)They merely sample everything that moves and discard the inorganic debris

Question 28

Ctenophores capture food by

A)nematocysts.
B)collenchyme.
C)colloblasts.
D)comb plates.
E)statocysts.

Question 29

Which statement about Cnidaria is NOT true?

A)Reproduction is both sexual and asexual
B)Some forms are sessile and others are motile
C)They live in either marine or freshwater environments
D)Tentacles are used to capture prey and put it into the mouth
E)The body plan is tube-within-a-tube,with a distinct mouth and anus

Question 30

Which of the following is a characteristic of stauromedusans?

A)They have a solitary polyp body
B)The top of the polyp has nine extensions
C)Polyps reproduce asexual
D)The planula swims initially and then becomes sessile
E)They do not have a mouth

Question 31

Hermaphroditic sea anemones that produce sperm first and eggs later,to prevent self-fertilization,are called

A)asexual.
B)pre-testicular.
C)postgynous.
D)protandrous.
E)precocious.

Question 32

Nematocysts are stinging organelles contained inside cells called __________________.

Question 33

The function of the siphonoglyph is

A)to form water currents into the gastrovascular cavity.
B)to sting the prey.
C)to aid in swimming.
D)to maintain balance or orientation.
E)reproduction.

Question 34

The function of the rhopalium is

A)digestive.
B)respiratory.
C)food capture.
D)sensory.
E)reproductive.

Question 35

Sea anemones and corals lack

A)a sexual stage.
B)an asexual stage.
C)a polyp stage.
D)a medusa stage.
E)None of the choices is correct

Question 36

The correct sequence in the life cycle of the jellyfish Aurelia is

A)planula,ephyra,scyphistoma.
B)scyphistoma,planula,ephyra.
C)planula,scyphistoma,ephyra.
D)ephyra,planula,scyphistoma.
E)None of the choices is correct

Question 37

If you removed the statocyst from a ctenophore,the most likely symptom you would notice would be

A)they would sting other ctenophores.
B)disorientation or swimming in a haphazard manner.
C)inability to expel wastes.
D)prevention of respiration.
E)lack of reproduction.

Question 38

A/An ____________________ is close to the land and has either no lagoon or a very shallow lagoon.

A)atoll
B)barrier reef
C)bank or patch reef
D)fringing reef
E)reef crest

Question 39

Hermatypic corals have mutualistic algal cells in their tissues called

A)coralline algae.
B)zooxanthellae.
C)kelp.
D)euglena.
E)colloblasts.

Question 40

Which of the following associations of cubozoan traits is NOT correct?

A)Velarium-where the subumbrellar edge turns inward
B)Pedalium-a flat,tough blade at the base of each tentacle
C)Ephyrae-a major stage of cubozoans between polyps and medusae
D)Medusae-in cross section,almost square
E)None of the choices is correct

Question 41

Ctenophores are propelled by eight plates bearing long,fused _____________.

Question 42

A distinguishing characteristic of cubozoan medusae is the presence of flattened blades called ___________ at the base of the tentacles.

Question 43

The tall secretory cells around the pedal disc and mouth of hydra are the ______ cells.

Question 44

The mesoglea of scyphozoans has amoeboid cells and fibers and is called a __________________.

Question 45

Gastric filaments bearing _________________ are found in scyphozoan medusae.

Question 46

Consider that you are a biology teacher with limited budget and want to order hydra that can last across many seasons and some irregularity in food supply due to school holidays.You can order regular white hydra or green hydra.Without any further information,which do you order and why?

Question 47

The long thread-like structures that help to overcome prey and provide defense in sea anemones are called ________ ________.

Question 48

Septa extending from the body wall to the pharynx in sea anemones are designated primary septa or ________________.

Question 49

The small organs of equilibrium in scyphozoan jellyfishes are called ______________,and these are borne in more complex sense organs called rhopalium.

Question 50

Describe the evidence for the likely order of appearance of life-cycle stages in the evolution of Cnidarians.Evaluate the validity of conclusions that are drawn from this evidence.

Question 51

The part of a coral reef that slopes down into the lagoon is the ________ ________ or fore reef slope.

Question 52

The free-swimming __________ larva is similar to an adult ctenophore and develops directly into an adult.

Question 53

Describe how food absorption in sponges differs from food absorption in Cnidaria.

Question 54

The polypoid stage of scyphozoans is called ________________.

Question 55

Corals important in formation of coral reefs have zoxanthellae in their tissues and are known as ________________ corals.

Question 56

Explain why the presence of a gelatinous layer between the ectoderm and endoderm in ctenophores and cnidarians make understanding the branching order of these phyla difficult.

Question 57

Describe the trigger mechanism and the process by which nematocysts are ejected at terrific pressure.

Question 58

Water in the gastrovascular cavity serves as a ________________ skeleton.

Question 59

The gastrodermal tubes that run through the extensive mesoglea of alcyonarians are called _______________.

Question 60

"Glue" cells in ctenophores that function in catching small animals are called ___________.

Question 61

Discuss the evolution of the Mesozoa,the Parazoa,and the Cnidaria.What are the common features shared by these groups?

Question 62

Discuss the evidence for the phylogenetic placement of Ctenophores and Cnidarians in the metazoan tree.

Question 63

Explain the controversy over distinguishing the body symmetry of cnidarians.