Corals

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Phylum
Cnidaria
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Class
Anthozoa
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When did corals evolve?
Cambrian- extant
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Name the two layers that the body consists of
Outer ectoderm and inner endoderm
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What are the stinging cells called?
Nematoblasts
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What is the skeleton made of?
Calcium carbonate
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What is a polyp?
Soft bodied organism that secretes a calcium carbonate skeleton
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What is the corallum?
Whole skeleton of a solitary or colonial coral
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What are the two main types of coral?
Solitary and compound
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Describe solitary corals
Only one polyp which secretes a single skeleton
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Describe a compound corals
Many polyps living together in a communal fashion, with many skeletons or corallites fused together
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What are the three orders of corals that are important in the fossil record
1. Rugose 2. Tabulate 3. Scleractinia
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Describe a rugose coral
Extinct colonial or solitary coral. wrinkled outer epitheca layer, horn shaped, no mural pores, show bilateral symmetry, always have a columella and may have dissepiments between the septa, six primary septa at
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Describe a tabulate coral
Extinct, always colonial with well developed tabulae, small corallites & mural pores may be present in some species, show radial symmetry, poor septa, may have dissepiments
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Describe scleractinian corals
Either solitary or colonial, extant, small corallites, no mural pores between the colonial forms, show radial symmetry known as hexagonal symmetry, six primary septa and evenly developed secondary septa, always have tabulae
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What are mural pores?
Connections between adjacent corallites, perhaps for communication
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What are zooxanthellae?
type of algae that lives inside modern-day coral cells
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What is a symbiotic relationship?
Describes two organisms living together for mutual benefit, neither of which can successfully live without the other- algae and coral
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Where does photosynthesis occur in the coral?
Occurs in the zooxanthellae as they contain chloroplasts inside their cells, carbond dioxide, phosphates and nitrates produced as wast form the coral are used by them to produce oxygen, amino acids and sugars
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Is the soft tissue preserved in corals?
no
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How does the coral feed?
The polyp has tentacles which extend for feeding purposes, usually at night, food particles in the water or zooplankton are extracted-paralysed by the nematoblasts or trapped in mucus secreted, it is then passed to the mouth & to the primitive gut
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How is waste removed?
They do not have an anus so undigested material and waste is removed through the mouth
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Where are modern day corals found?
Seas and oceans
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What zone do reef building corals occupy?
30 degrees north and 30 degrees south of the equator, they are considered tropical
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Why is water depth important for corals?
They need to be at or just below sea level, water depth is important as light is filtered out at depth, reef building corals are rarely found below 30m
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Why is clear water important for corals?
They need sunlight so the algae can photosynthesise, the water needs to be free from particles of mud and sediment so it does not clog the polyps- they tend to be offshore and far from rivers
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Why do they need high-energy levels or wave action?
Incorporates more oxygen into the water and circulates the correct level of nutrients by upwelling
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What temperature is needed?
23 degreees and 27 degrees
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Do they need salinity?
Yes but between 30-4 parts per thousand
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Name a modern example of a coral reef?
Great barrier reef
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Name the 3 types of modern reefs
1. fringing reefs 2. Barrier reefs 3. Atolls
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What is a fringing reef?
Fringing reefs meet the land and some parts may be above sea level at low tide
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What is a barrier reef?
They are further out to sea with a lagoon separating the land from the reed
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What is a coral atoll?
Ring shaped reefs found offshore, the formation of atolls is due to hot spot activity as the volcanoes create an area of shallow sea, the weight of the volcano means the crust gradually sinks and the moho sags below the shield volcano
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What is the average growth rate for modern corals?
1 and 10cm per year
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Other cards in this set

Card 2

Front

Anthozoa

Back

Class

Card 3

Front

Cambrian- extant

Back

Preview of the back of card 3

Card 4

Front

Outer ectoderm and inner endoderm

Back

Preview of the back of card 4

Card 5

Front

Nematoblasts

Back

Preview of the back of card 5
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