Chapter 8-Porifera and Cnidaria Flashcards

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1
Q

What are the simplest forms of metazoans?

A

Porifera and Cnidaria

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2
Q

What type of animals are in the Phylum Porifera?

A

sponges

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3
Q

T/F Spongs are the simplest and most inanimate of all metazoans.

A

True

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4
Q

What separates sponges form all other animals?

A

lack of defined body symmetry and lack of tissues such as muscles and nerves

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5
Q

What does a sponge’s simple design accomplish?

A

primary functions of feeding, reproduction, and adaptive responses to the environment

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6
Q

Do sponges exhibit a cellular level or organization?

A

yes

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7
Q

What types of animals are in the Phylum Cnidaria?

A

hydras, jellyfish, corals and sea anemones

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8
Q

What type of organization do animals in Phylum Cnidaria exhibit?

A

tissue-level

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9
Q

What does tissue-level organization mean?

A

have muscles and nerves yet lack organs

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10
Q

What are 2 features unique to cnidarian?

A

radial symmetry and diploblastic

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11
Q

What does diploblastic mean?

A

two germ layers, ectoderm and endoderm, produced during embryonic development

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12
Q

What does triploblastic mean?

A

animals with 3 germ layers produced in embryonic development

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13
Q

Where do sponges primarily live?

A

marine environments, 150 species found in freshwater

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14
Q

How are sponges sessile organism?

A

attach themselves to rocks and other substrates with their sac-like body supported by water

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15
Q

What kind of support do sponges exhibit?

A

skeleton made up of inorganic spicules or interconnecting collagen fibers known as spongin

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16
Q

What are the flagellated cells called that line the chambers in sponges?

A

choanocytes

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17
Q

What do choanocytes do?

A

circulate water and filter microscopically small food particles

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18
Q

What is remarkable about the cell of a sponge?

A

plastic; individual cell types can differentiate to an amoeboid form and then redifferentiate into other cel types

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19
Q

T/F Single sponge cells can be the basis for entire colonies.

A

True

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20
Q

What are the two ends of the sac-like body of sponges called and used for?

A

basal end for attachment and upper end is an opening called an osculum

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21
Q

What lines the osculum?

A

long spicules

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22
Q

What is the spongocoel?

A

opening which runs the entire length down the center of the sponge

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23
Q

What are the pores called that allow water to enter sponge?

A

dermal ostia

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24
Q

What are the incurrent canals?

A

water enters through dermal ostia

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25
Q

What is the radial canal?

A

adjacent to incurrent canals separated by a layer of cells

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26
Q

What are porocytes?

A

special cells that allow water to pass through the radial canal

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27
Q

What canal do choanocytes line?

A

radial canal

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28
Q

What do the flagella do?

A

produce water currents that bring in food particles and oxygen; food particles are digested in food vacuoles

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29
Q

The remaining water and indigestible material pass along radial canals to spongocoel and then out through what?

A

osculum

30
Q

What is the simplest body plan of sponges?

A

asconoid

31
Q

What are characteristics of asconoids?

A

small and tube-shaped, limited internal surface area over which to filter water for food

32
Q

What are characteristics of syconoids?

A

folds (convolutions) in body walls

33
Q

What type of body plan does Grantia have?

A

syconoid

34
Q

What are characteristics of leuconoids?

A

majority of sponge species, exhibit more folding than seconds, including a complex labyrinth of internal chambers

35
Q

What is classification based upon in sponges?

A

shape and composition of their spicules

36
Q

What are the 3 classes of sponges?

A

Calcarea, Hexactinellida, and Demospongiae

37
Q

What are characteristics of Class Calcarea?

A

only class with spicules composed of calcium carbonate, spicules are needle-shaped, 3 or 4 pronged, and seldom grouped together; typically small and include all 3 levels of body complexity (asconoid, syconoid, leuconoid); usually found in shallow coastal waters

38
Q

What are characteristics of Class Hexactinellida?

A

six-rayed spicules made from silica, more symmetrical compared to other classes; can be shaped like a cup, vase, or urn; body shape only syconoid or leuconoid, never asconoid; a type of sponge called Euplectella have male and female shrimp often reside within spongocoel growing too large to escape

39
Q

What are characteristics of Class Demospongiae?

A

95% of species, all are leuconoid, skeleton consists of spongin fibers, siliceous spicules, or combination of both; spicules are six-rayed; includes Spongia which contain spongin fibers but lacks spicules

40
Q

How do sponges reproduce?

A

asexually and sexually

41
Q

What does hermaphroditic mean?

A

produce both male and female gametes (sperm and eggs), but usually produced at different times

42
Q

What happens during sexual production in sponges?

A

sperm released in large amounts through osculum, when sperm gift into contact with another sponge, swept in via sponge’s incurrent water flow; once inside, sperm captured by choanocytes; transported toes in messily where fertilization takes place, newly formed embryos expelled from sponge after short period of development

43
Q

What happens during asexual production in sponges?

A

involves either budding of new sponge from base of parent, or in the case of freshwater sponges, release of gemmules in autumn; in winter, parent sponges will disintegrate but gemmules can withstand freezing and develop mature sponges the following spring

44
Q

What type of symmetry do cnidarians have?

A

radial symmetry

45
Q

What is a central point in cnidarians?

A

mouth that extends into the gastrovascular cavity

46
Q

Do cnidarians have an anus?

A

no

47
Q

What are cnidocytes?

A

stinging cells that line tentacles and surround central mouth which contain nematocysts

48
Q

What are nematocysts?

A

coiled threads that can be discharged like tiny harpoons to aid in prey capture or in defense against predators

49
Q

What do the body walls cnidarians consist of?

A

outer epidermis for protection and an inner gastrodermis for digestion; between these two layers is a jellylike mesoglea (particularly thick in jellyfish)

50
Q

What are the 2 basic body forms in cnidarians?

A

sessile polyp and medusa

51
Q

What do polyps do?

A

adhere to substrate by aboral surface, with mouth and tentacles extended outward for feeding

52
Q

What do medusa do?

A

free-swimming and disc or umbrella-shaped, with mouth and tentacles on lower surface

53
Q

What is it called when cnidarians alternate between two forms?

A

polymorphic life cycle

54
Q

What are the 3 classes of cnidarian?

A

Class Hydrozoa, Class Scyphozoa, Class Anthozoa

55
Q

What are characteristics of Class Hydrozoa?

A

includes organisms like hydra and Obelia, polyp is predominant body-form, most have medusa stage as well

56
Q

What are characteristics of Class Scyphozoa?

A

includes the jellyfish and scyphozoans, life cycle that emphasizes medusa form over polyps

57
Q

What are characteristics of Class Anthozoa?

A

sea-anemones and corals, express only the polyp body form

58
Q

What are characteristics of Hydra?

A

found in shallow freshwater ponds, stinging cnidocytes to capture small invertebrate prey, lac medusa stage in life cycle, this feature is atypical in the class

59
Q

What are characteristics of Obelia?

A

colonial hydrozoan found in shallow marine waters attached to substrates such as seaweed or rocks, alternates between polyp and medusa body form in life cycle, medusa is the sexual stage producing male/female gametes, polyp produces new medusae asexually

60
Q

What are gastrozoids?

A

feeding polyps with tentacles

61
Q

What are gonozoids?

A

reproductive polyps contain medusa buds and lack tentacles

62
Q

What happens when medusae buds mature?

A

break away from gonozoid and become free swimming female and male medusae, medusa produce gametes, fertilization form a zygote that eventually develops into a planula larvae, when larva eventually settles on the substrate it develops into a new polyp colon and cycle repeats

63
Q

What are characteristics of Physalia?

A

known as Portuguese Man-of-War, floating colony of highly integrated polymorphic polyps and medusoids that look like jellyfish; some form gas-filled sac and some are suspended as long tentacles

64
Q

What is the gas-filled sac in in Physalia called?

A

pneumatophore

65
Q

What are the tentacles armed with on Physalia?

A

armed with a battery of cnidocytes used to sting and capture prey

66
Q

What are some characteristics in Class Scyphozoa?

A

jellyfish; medusa stage dominates life cycle whereas polyp reduced to small larval form, mostly free swimming marine organisms; food swept into mouth by ciliated oral arms, after food digested in gastrovascular cavity, nutrients transported around body via a system of radial canals and circular canal

67
Q

What is the name of the Scyphozoan we looked at in class?

A

Aurelia

68
Q

What are the small gaps on the tentacles of Aurelia and how many are there?

A

8; each gap contains sense organ which is sensitive to light, chemicals, and body position

69
Q

What are some characteristics of Class Anthozoa?

A

solitary (sea anemones) or modularly colonial (corals) marine organisms, non-polymorphic, exhibiting only polyp form of cnidarian life cycle; may or may not secrete an external supporting calyx of calcium carbonate in which they are embedded

70
Q

What is the actonia in Anthozoa?

A

thread-like structures with stinging cells (immobilize food)