Cnidarians Flashcards

1
Q

How are solitary corallites formed?

A

polyps which live an individual existence and do not form part of a colony

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2
Q

Where can many solitary corals be found among?

A

Rugosa and Scleractinia (extinct solitary corals)

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3
Q

How are colonies produced from an individual founding polyp?

A

asexual reproduction

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4
Q

What is the advantage to coral colonies forming?

A

capacity for increased size and stability and greater efficiency in feeding and other major life processes

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5
Q

What are the skeletons secreted by colonial corals said to be?

A

Compound (leading to widely variable morphology)

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6
Q

What are some examples of Cateniforms?

A

Halysites; Tabulate

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7
Q

What are Canteniforms like?

A

corallites are joined laterally to form palisades

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8
Q

Would do horizontal section of canteniforms resemble?

A

links in a chain

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9
Q

What are some examples of Cerioids?

A

Lonsdaelia; Rugosa

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10
Q

What are Cerioids?

A

walls of the adjacent corallites are joined to produce a polygonal pattern in cross section

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11
Q

What is an example of a phaceloid?

A

Syringopora; Tabulata

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12
Q

What are phaceloids?

A

a type of fasciculate coral in which the cylindrical corallites are approximately parallel with each other

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13
Q

What is an example of Thamnasteroid?

A

Phillipsastraea; Rugosa

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14
Q

What are Thamnasteroids?

A

absence of Epithecal so the septa (walls/plates) adjacent corallites join each other

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15
Q

What is the common growth forms of Thamnasteroids?

A

Scleractinian corals (also in extinct rugose corals)

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16
Q

What do rugose corals show?

A

degree of bilateral symmetry since the metasepta are only inserted in 4 areas

17
Q

What can obscure the bilateral symmetry of rugose corals?

A

the large number of septa

18
Q

What are the characteristics of most rugosa corals?

A

Well developed septa
Dessepiments and tabulae
Columella or other axial structure

19
Q

What is the epitheca (upper of coral) like for rugosa corals?

A

almost always prominent and generally thick and wrinkled

20
Q

What were rugosa like between the middle Ordovician and the lower Llandovery?

A

Most species small and solitary

20
Q

When did rugosa occur?

A

Middle Cambrian
(but typical examples not till middle Ordovician)

21
Q

What took place in the Silurian regarding rogusa?

A

diversification that meant rugosa became an important element of reef faunas

22
Q

When did rugosa start to decline?

A

in the later carboniferous and then persisted till extinction at the end of the Permian

23
Q

Are Tabulates solitary or colonial?

A

Colonial

24
Q

What are the characteristics of Tabulates?

A

corallites are usually small with prominent tabulae
Septa reduced or absent

25
Q

What is coenosteum?

A

skeletal tissue between the corallites secreted by a sheet of tissue that joined the polyps in life

26
Q

When are Tabulates thought to have occured?

A

Cambrian but undoubted presence in the lower Ordovician

27
Q

When were are tabulates extinct?

A

By the end of the permian

28
Q

What corals does the Scleractinia order cover?

A

All post lower Triassic corals

29
Q

How can Scleractinia be distinguished from Rugosa?

A

Septal insertion

30
Q

What is septa insertion like for Scleractinia?

A

Inserted in multiples of six each insertion cycle must be completed before the next cycle

31
Q

What is the epitheca like in Scleractinia?

A

poorly developed or absent

32
Q

What is the skeletal composition of Scleractinia?

A

Aragonites (with other corals being low-Mg calcite)

33
Q

What did Scleractinia evolve from?

A

A soft bodied organism instead of Rugosa or Tabulate