Transcript CORALS

http://www.youtube.com/watch?v=lBgh_YmY4lU amazing habitat (polyps
 coral)
http://www.youtube.com/watch?v=cbN161yBBGA coral reefs in danger as
people fish for rare species
http://www.youtube.com/watch?v=AA42hW4nHbg&feature=related coral
reef close up – very diverse
CORALS
most simple group for
terminology on our
specification!
http://www.youtube.com/watch?v=
wsaZ8-I7akg corals spawning
http://www.bbc.co.uk/nature/life/A
nthozoa#p00n6tnv spawning!
CNIDARIA/CORALS
You could learn lots
about them! But we
only have to learn
septa and colonial/solitary
Phylum:
Cnidaria: (formerly called Coelenterata)
Class:
Anthozoa: (corals)
Hydrozoa: (hydroids)
Scyphozoa: (jellyfish)
Sub-Classes:
Zoantharia:
Rugosa (extinct)
Tabulata (extinct)
Scleractina (reef building, still exist part of the
Zoantharia).

The polyps are solitary or
colonial.
 The soft parts are divided
into 6, 8 or more.
 Often have a bilateral
symmetry.
 Marine.
http://www.bbc.co.uk/nature/li
fe/Anthozoa#p00ms41r corals
and plants relationship
“Bag of guts”
MORPHOLOGY:

Corals are usually sack
shaped (widest at the top)
which contained the
MOUTH narrowing at the
base where it was
attached.
 The body structure is
simple with a hard calcite
outer layer and an inner
body cavity.
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http://www.bbc.co.uk/nature/life
/Anthozoa#p00dhm3h
SOFT PARTS:

The body cavity is divided into
small segments by RADIAL
MESENTERIES (partitions)
which give it stability and
strength and provide more
efficient feeding.
 Outer Layer = ECTODERM
 Inner Layer = ENDODERM
 The inner body cavity =
COELENTERON (ENTERON)
 WE DON’T SEE ANY OF THIS
IN FOSSIL FORM!

Mesenteries increase surface
area and help digestion of food.
 The MOUTH is usually towards
the centre and has a number of
functions:
1. Takes in food.
2. Allows discharge of waste.
3. Discharge of larvae.
 The mouth is surrounded by
retractable tentacles, which
have stinging organs on them.
 Some corals show a bilateral
symmetry but more commonly
show radial symmetry
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solitary
Coralite is conical in
shape.
The skeleton grew
upwards from a narrow
base.
Plenty of space to grow
= ROUNDED shape
The whole structure
can be straight or
curved (horn shaped).

CALICE appears like a
depression and in this
can be seen a central
region called the AXIAL
REGION.
 The ends of the SEPTA
can also be seen
sometimes.
 A COLUMELLA may be
present in the centre
(rod like)
Colonial/Compound Corals

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Lots of them
a colony
Often short of space
for growth
Polygon shaped
Competition for
food etc
http://www.bbc.co.uk
/programmes/p00msn
8q coral turf wars!
Colonial/Compound Corals

In colonial corals there
are often a large
number of septa.
 TABULAE: These
represent former levels
of the calice floor,
secreted by the polyp
to seal off the lower
area of the corallum.
 They are best seen if
longitudinal sections
are cut.
Colonial/Compound Corals

They are made up of varying
numbers of individuals each called
a corallite.
 They are subdivided based on the
relationship between the corallites:
FASCICULATE:
 The individuals are not closely
touching.
 Fasciculate corals can be further
sub divided:
DENDROID:
 They branch irregularly.
PHACELOID:
 If the corallites are parallel to each
other.
Colonial/Compound Corals

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MASSIVE:
All the corallites are in
contact.
These are also further sub
divided:
CERIOID:
Polygonal corallites in
cross section and they
have a clear dividing wall.
ASTRAEOID:
The walls are absent.
Mode of life and
palaeoenvironment (Index Fossil)
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Sessile apart from when in
larval stage.
Benthonic and fixed.
lived in warm (22 - 29ºC
ideally 25ºC) tropical.
Shallow seas ideally <25 m
continental shelf.
They like clear water with little
sediment.
Well oxygenated, high energy.
Typically found in carbonate
rocks especially in the
Carboniferous.
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Scleractinian corals Middle
Triassic to Recent.
Most important in the Jurassic.
Not very important in the
Cretaceous (but can be found in
the Chalk)
In the present they form important
reef building animals in the
tropics and sub tropics around
ocean islands and east coasts of
large landmasses.
http://www.bbc.co.uk/news/world-europe-16026961
insurance policy for the future
http://www.bbc.co.uk/programmes/p
00msl9l colourful at night!