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Eaes 360 Paleontology > Porifera/Cnidaria > Flashcards

Porifera/Cnidaria Flashcards

1
Q

Types of cells in porifera

A

Multicellular, but not organized into organs or tissues.

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2
Q

What is considered to be the sister group to all metazoans?

A

Porifera

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3
Q

Porifera

A

*Mostly marine, a few freshwater *Virtually all are sessile, epifaunal, filter feeders *Porifera = “pore bearers” - bodies punctured by numerous pores

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4
Q

Pores in Porifera

A

*Water flows into the body through the pores-incurrent *Associated with pores are cells with flagella - whip like process - aid in moving water through body of sponge

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5
Q

Choanoflagellates

A

*small single celled protists *Found in freshwaters and the ocean *take their name (“collar-flagellates”) fromthe circle of closely packed microvilli, or slender fingerlike projections, that surrounds the single flagellum by which choanoflagellates both move and take in food. *Closest protist relative to metazoa

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6
Q

microvilli

A

Slender fingerlike projections that surrounds that single flagellum by which chanoflagellates move and take in food.

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7
Q

spongocoel

A

In sponges, a central chaimber that water moves into.

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8
Q

osculum

A

In sponges water leaves via a large opening.

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9
Q

Ascon grade sponges

A

generally small (small ratio area/volume)

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10
Q

leuconoid sponges

A

Most sponges, and all large ones, (large ratio area/volume)

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11
Q

Sycon sponges

A

The middle sponges in terms of ratio area/volume. Shows folding along the edges

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12
Q

Sponge skeletons

A

*calcareous plates *Organic collagen like fibers (bath sponges) *siliceous and calcareous spicules

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13
Q

spicules

A

Needle like elements in sponge skeletons

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14
Q

Sponge skeleton fossilization

A

Plates and spicules fossilize well, but most skeletons dissagregate at death

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15
Q

Class Calcarea

A

*Cambrain-Recent ❁skeleton composed of separate calcareous spicules ❁all three grades ❁marine, usually shallow ❁Generally small

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16
Q

Class Demospongiae

A

❁90-95% sponge species ❁siliceous spicules, of spongin fibres, or both. ❁Leuconoid only ❁Most marine, some freshwater

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17
Q

Class Hexactinellida

A

Late Precambrian-Recent ❁”glass sponges”, ❁construct a skeleton composed of 6-rayed siliceous spicules ❁syconoid pattern ❁Exclusively marine, usually deep ocean

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18
Q

Stromotoporoid

A

❁extinct group of massive calcareous colonial marine organisms ❁ important Paleozoic and Mesozoic reef builders. ❁For a long time affinities were unclear ❁Massive calcareous skeletons - up to 5 m in diameter, variety growth forms ❁Horizontal and vertical structures

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19
Q

When do stromotoporoid reef builders disappear?

A

Paleozoic forms dissapear end Devonian - collapse reef ecosytems, unclear if Mesozoic forms are same group

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20
Q

laminae

A

Horizontal layers parallel to substrate in stromotoporoids

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21
Q

mammelons

A

Raised surfaces, bumps, in stromotoporoids

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22
Q

astrorhizae

A

“Star roots” look like stars in stromotoporoids

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23
Q

Coralline Sponges

A

❁Originally discoverd in 1970’s in cryptic habitats in reefs ❁leuconoid sponges with siliceous spicules (”sclerosponges”), calcareous spicules, or no spicules; with a massive calcareous basal skeleton ❁May be polyphyletic (most demosponges; some Calcarea) ❁Almost certainly living relatives of stromatoporoids ❁Experimental work on model “stroms” show they could function as sponges. ❁Grow slowly; can be used as climate proxies

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24
Q

Archeocyathids

A

Another enigmatic group ❁Calcareous sessile marine organisms ❁Range restricted to Lower-Middle Cambrian ❁Very diverse in lower Cambrian ❁Shallow water, usually carbonates ❁Reef builders ❁Tropical

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25
Q

Receptaculitids

A

“Sunflower coral” ❁Radially symmetrical carbonate skeleton made of rods ❁Shallow water tropical environments - reefs ❁Ordovician - Pemian; most Ord.-Dev. -common in Ordovician of Illinois (and Missouri) ❁Resemble sponges - probably superficial ❁Current view is that they may be calcareous green algae

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26
Q

What type of animals are Cnidarians?

A

Sea anemones, corals, jellyfish, sea pens, hydra

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27
Q

cnidarians

A

the “nettle keepers” *Wide variety body forms and complex life cycles *All possess nematocysts *Bodies made of two layers of tissue (epidermis and gastrodermis) *In between epidermis and gastrodermis is the mesoglea, a layer of jellylike substance which contains scattered cells and collagen fibers.

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28
Q

Forms of cnidarians

A

❁Solitary or colonial (colonies can be massive) ❁Free-living or sessile ❁Soft bodied or calcareous

29
Q

nematocysts

A

Stinging threads used to protect animal and/or capture prey.

30
Q

Epidermis in cnidarians

A

contains the cnidocysts, the stinging cells that are characteristic of the phylum

31
Q

Two general body forms of cnidarians

A

Medusa-Generally free living (tentacles on bottom)

Polyp-Generally sessile; may secrete calcareous skeleton

32
Q

Hydrozoa

A

alternate between a polyp and a medusa stage - siphonophores, hydroids, fire corals, and many medusae

33
Q

Anthozoa

A

live only as polyps - true corals, anemones, and sea pens

34
Q

Cubozoa

A

Box Jellies-toxic

35
Q

Scyphozoa

A

medusa stage dominates; true jellyfish

36
Q

What type of living form is this?

A

medusa-free living form

37
Q

What type of body form is this?

A

Polyp-generally sessile. May secrete a calcareous skeleton.

38
Q

Coral like fossil forms first appear…

A

In the Cambrian

39
Q

Earliest Cnidarians are known from the

A

Ediacarian (late Pre Cambrian)

40
Q

Scleractinian Corals

A

❁Body internally divided by partitions: mesenteries ❁Secrete skeleton of aragonite = corallite ❁Radial sheets of aragonite = septa, secreted between pairs of mesentaries ❁Septa show six -fold radial symmetry (cyclic insertion) ❁Can be solitary or colonial ❁Many have symbiotic alga which allow them to become quite large - especially in tropics ❁Middle Triassic -Recent

41
Q

Body internally divided by partitions

A

mesentaries

42
Q

Rugose Corals

A

Horn corals

❁Skeletons of calcite ❁Important in ancient reefs ❁Both solitary and colonial (compound) ❁Bilateral pattern of septa (serial insertion) ❁Ordovician - Permian

43
Q

Tabulate Corals

A

❁Exclusively colonial

❁Calcite skeleton

❁Important reef builders

❁Corallite made of slender tubes crossed by horizontal internal partition - tabulae

❁Septa reduced or absent

44
Q

Secreted skeleton of aragonite

A

corrallite

45
Q

How are coral groups related?

A

❁Mineralogy- calcite vs. Aragonite

❁Morphology - insertion

❁Time gaps - no Lower Triassic corals

46
Q

Original meaning of a reef

A

a ridge or shoal a ship could ground on - still used in this sense - we have “reefs” in Lake Michigan

47
Q

Reefs are composed of…

A

carbonates (limestone dolomite)

48
Q

Carbonate buildup

A

a body of locally formed and laterally restricted carbonate sediment possessing topographic relief

49
Q

moundlike organic buildup

A

bioherm

50
Q

Reef

A

buildup formed in part by a wave-resistant framework constructed by organisms - a waveresistant bioherm

51
Q

If a reef is not wave resistant it is called a….

A

bank

52
Q

Where are reefs located?

A

In less that 1% of the oceans. They are restricted to 30N and 30S. TEmp must be between 18 and 36C. Clear, shallow waters, with low nutrients and low sedimentation.

53
Q

modern reefs are built by

A

scleractinian corals

54
Q

zooxanthellae in reefs

A

symbiotic algae. This means the reefs need light.

55
Q

Is it easier to precipitate calcium carbonate in colder or warmer waters?

A

warmer waters.

56
Q
A

Fringing Reef.

builds directly out from coast

57
Q
A

Barrier Reef

separated from coast by a shallow lagoon

58
Q
A

Atoll

ringlike, surrounds lagoon - most modern IndoPacific island reefs

59
Q

3 basic classes of modern reef builders

A

❁Frame builders: make structure of reef; generally scleractinian corals

❁Binders: cement reef materials together - algae

❁Debris producers: all organisms living on or around reef

60
Q

Why are reefs of particular interest to geologists?

A

Important source rock for petroleum due to high productivity of the reef environment and porous structure

61
Q

proterozoic reefs

A

Algal stomatalites produce small scale buildups

Decline markedly end Proterozoic - evolution grazers?

62
Q

when was the beginning of true reefs?

A

Ordovician. bioherms.

❁These reefs become large and widespread in the Silurian and Devonian

63
Q

What were reefs like in the carboniferous?

A

There were none, only mounds.

64
Q

Permian reefs

A

❁Widespread reefs reappear, e.g., west Texas ❁Framebuilders are bryozoans and calcareous sponges ❁Disappear end Permian

65
Q

Triassic reefs

A

first scleractinian corals; few reefs similar to those in Permian

66
Q

Jurassic reefs

A

explosion diversity scleractinian corals - become major reef element

67
Q

Cretaceous reefs

A

dominated by rudistid bivalves! - become extinct Late Cretaceous

68
Q
A

Eaes 360 Paleontology (14 decks)

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