Porifera/Cnidaria

Question 1

Types of cells in porifera

Answer 1

Multicellular, but not organized into organs or tissues.

Question 2

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

Answer 2

Porifera

Question 3

Porifera

Answer 3

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

Question 4

Pores in Porifera

Answer 4

*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

Question 5

Choanoflagellates

Answer 5

*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

Question 6

microvilli

Answer 6

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

Question 7

spongocoel

Answer 7

In sponges, a central chaimber that water moves into.

Question 8

osculum

Answer 8

In sponges water leaves via a large opening.

Question 9

Ascon grade sponges

Answer 9

generally small (small ratio area/volume)

Question 10

leuconoid sponges

Answer 10

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

Question 11

Sycon sponges

Answer 11

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

Question 12

Sponge skeletons

Answer 12

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

Question 13

spicules

Answer 13

Needle like elements in sponge skeletons

Question 14

Sponge skeleton fossilization

Answer 14

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

Question 15

Class Calcarea

Answer 15

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

Question 16

Class Demospongiae

Answer 16

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

Question 17

Class Hexactinellida

Answer 17

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

Question 18

Stromotoporoid

Answer 18

❁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

Question 19

When do stromotoporoid reef builders disappear?

Answer 19

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

Question 20

laminae

Answer 20

Horizontal layers parallel to substrate in stromotoporoids

Question 21

mammelons

Answer 21

Raised surfaces, bumps, in stromotoporoids

Question 22

astrorhizae

Answer 22

“Star roots” look like stars in stromotoporoids

Question 23

Coralline Sponges

Answer 23

❁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

Question 24

Archeocyathids

Answer 24

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

Question 25

Receptaculitids

Answer 25

"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

Question 26

What type of animals are Cnidarians?

Answer 26

Sea anemones, corals, jellyfish, sea pens, hydra

Question 27

cnidarians

Answer 27

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.

Question 28

Forms of cnidarians

Answer 28

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

Question 29

nematocysts

Answer 29

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

Question 30

Epidermis in cnidarians

Answer 30

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

Question 31

Two general body forms of cnidarians

Answer 31

Medusa-Generally free living (tentacles on bottom) Polyp-Generally sessile; may secrete calcareous skeleton

Question 32

Hydrozoa

Answer 32

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

Question 33

Anthozoa

Answer 33

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

Question 34

Cubozoa

Answer 34

Box Jellies-toxic

Question 35

Scyphozoa

Answer 35

medusa stage dominates; true jellyfish

Question 36

What type of living form is this?

Answer 36

medusa-free living form

Question 37

What type of body form is this?

Answer 37

Polyp-generally sessile. May secrete a calcareous skeleton.

Question 38

Coral like fossil forms first appear...

Answer 38

In the Cambrian

Question 39

Earliest Cnidarians are known from the

Answer 39

Ediacarian (late Pre Cambrian)

Question 40

Scleractinian Corals

Answer 40

❁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

Question 41

Body internally divided by partitions

Answer 41

mesentaries

Question 42

Rugose Corals

Answer 42

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

Question 43

Tabulate Corals

Answer 43

❁Exclusively colonial ❁Calcite skeleton ❁Important reef builders ❁Corallite made of slender tubes crossed by horizontal internal partition - tabulae ❁Septa reduced or absent

Question 44

Secreted skeleton of aragonite

Answer 44

corrallite

Question 45

How are coral groups related?

Answer 45

❁Mineralogy- calcite vs. Aragonite ❁Morphology - insertion ❁Time gaps - no Lower Triassic corals

Question 46

Original meaning of a reef

Answer 46

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

Question 47

Reefs are composed of...

Answer 47

carbonates (limestone dolomite)

Question 48

Carbonate buildup

Answer 48

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

Question 49

moundlike organic buildup

Answer 49

bioherm

Question 50

Reef

Answer 50

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

Question 51

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

Answer 51

bank

Question 52

Where are reefs located?

Answer 52

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.

Question 53

modern reefs are built by

Answer 53

scleractinian corals

Question 54

zooxanthellae in reefs

Answer 54

symbiotic algae. This means the reefs need light.

Question 55

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

Answer 55

warmer waters.

Question 56

Answer 56

Fringing Reef. builds directly out from coast

Question 57

Answer 57

Barrier Reef separated from coast by a shallow lagoon

Question 58

Answer 58

Atoll ringlike, surrounds lagoon - most modern IndoPacific island reefs

Question 59

3 basic classes of modern reef builders

Answer 59

❁Frame builders: make structure of reef; generally scleractinian corals ❁Binders: cement reef materials together - algae ❁Debris producers: all organisms living on or around reef

Question 60

Why are reefs of particular interest to geologists?

Answer 60

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

Question 61

proterozoic reefs

Answer 61

Algal stomatalites produce small scale buildups Decline markedly end Proterozoic - evolution grazers?

Question 62

when was the beginning of true reefs?

Answer 62

Ordovician. bioherms. ❁These reefs become large and widespread in the Silurian and Devonian

Question 63

What were reefs like in the carboniferous?

Answer 63

There were none, only mounds.

Question 64

Permian reefs

Answer 64

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

Question 65

Triassic reefs

Answer 65

first scleractinian corals; few reefs similar to those in Permian

Question 66

Jurassic reefs

Answer 66

explosion diversity scleractinian corals - become major reef element

Question 67

Cretaceous reefs

Answer 67

dominated by rudistid bivalves! - become extinct Late Cretaceous