Brachiopods

Phylum: Brachiopoda

Classes: Articulata
Inarticulata
 
Orders: 7 Articulate
4 Inarticulate

1. Phylum:Phylum:BrachiopodaBrachiopoda
Classes:Classes:ArticulataArticulata
 InarticulataInarticulata
  
Orders:Orders:7 Articulate 7 Articulate 
 4 Inarticulate4 Inarticulate

2.  Copy diagram on page Copy diagram on page
125 a) and b) Black125 a) and b) Black to show  to show 
a typical articulate a typical articulate 
brachiopod.brachiopod.
They have 2 They have 2 VALVESVALVES  
(shells) that totally enclose (shells) that totally enclose 
the soft parts.the soft parts.
The average size is 20 - 70 The average size is 20 - 70 
mm but can range up to 370 mm but can range up to 370 
mm.mm.
The valves can open and are The valves can open and are 
hinged at one end; muscles hinged at one end; muscles 
open and close the shell.open and close the shell.

3. Morphology 2Morphology 2
They usually allow water into They usually allow water into 
the shell, as they are filter the shell, as they are filter 
feeders extracting food from feeders extracting food from 
seawater.seawater.
The two valves are different The two valves are different 
in size (as opposed to in size (as opposed to 
bivalves).bivalves).
However; they do show a However; they do show a 
line of lateral symmetryline of lateral symmetry  
along the middle of the along the middle of the 
animalanimal. . Highlight this on Highlight this on
your diagramyour diagram..

4. Morphology 3:Morphology 3:Naming of the valvesNaming of the valves
The smaller valve is the The smaller valve is the 
BRACHIAL BRACHIAL valve (upper in valve (upper in 
life position).life position).
The larger valve is the The larger valve is the 
PEDICLE PEDICLE valve (lower in life valve (lower in life 
position).position).
The animal secretes the The animal secretes the 
valves as it grows, the valves as it grows, the 
original small shell is called original small shell is called 
thethe UMBO UMBO and the shell  and the shell 
grows outwards from either grows outwards from either 
side of this point. side of this point. Make sure Make sure
that you can see the umbo that you can see the umbo
on a hand specimen.on a hand specimen.

5. Morphology 4: Morphology 4:
Often the pedicle valve has a Often the pedicle valve has a
small circular opening small circular opening
((FORAMENFORAMEN) at the end ) at the end
through which a type of foot through which a type of foot
extends called the extends called the
PEDICLEPEDICLE. . Make sure that Make sure that
you can see the foramen in you can see the foramen in
a hand specimen.a hand specimen.
The pedicle allows the The pedicle allows the
brachiopod to attach itself to brachiopod to attach itself to
the sea floor.the sea floor.
Inside the shell the body fills Inside the shell the body fills
much of the body cavity.much of the body cavity.

6. Morphology 5:Morphology 5:
Some shells like rhynchonellids Some shells like rhynchonellids
have a have a wrinkly COMMISUREwrinkly COMMISURE
with with FOLDSFOLDS (one on either (one on either
side of the sulcus)side of the sulcus) and a and a
SULCUS (in the middle)SULCUS (in the middle)..
Draw a rhynchonellid showing Draw a rhynchonellid showing
the fold and sulcus and the the fold and sulcus and the
inhalentinhalent and and exhalent exhalent currents.currents.
Folds have inhalent and sulcus Folds have inhalent and sulcus
has the exhalent.has the exhalent.
 The currents are therefore The currents are therefore
separated.separated.
The crenulated commissure The crenulated commissure
also provides a greater surface also provides a greater surface
area.area.

7. The inside of the shell is the The inside of the shell is the
MANTLE CAVITYMANTLE CAVITY and is mainly and is mainly
the the LOPHOPHORE, whichLOPHOPHORE, which is a is a
food gathering and water-food gathering and water-
filtering device.filtering device.
 Draw diagram (d) from Draw diagram (d) from
page 125 Black.page 125 Black.
The important muscles are:The important muscles are:
At the posterior end is the At the posterior end is the
pedicle “foot” type of pedicle “foot” type of
ligament/muscle which when ligament/muscle which when
extended could usually reach extended could usually reach
outside of the shell.outside of the shell.
The main muscles were the The main muscles were the
ADDUCTOR and DIDUCTOR ADDUCTOR and DIDUCTOR
muscles, which were used to muscles, which were used to
close the shell.close the shell.

8. Internal morphology 2:Internal morphology 2:
 Draw diagrams from page Draw diagrams from page
125 Black:125 Black:
c)c) for muscle position. for muscle position.
e) and f)e) and f) showing internal views showing internal views
of shells with muscle scars.of shells with muscle scars.
Both sets of muscles were Both sets of muscles were
attached to the shell and attached to the shell and
although not preserved in the although not preserved in the
fossils there are scars left from fossils there are scars left from
where the muscles were where the muscles were
attached to the shell.attached to the shell.
The The CARDINAL PROCESSCARDINAL PROCESS and and
HINGEHINGE acts as a fulcrum on acts as a fulcrum on
which the muscles can pull.which the muscles can pull.
The diductor muscles contract The diductor muscles contract
and pull down the cardinal and pull down the cardinal
process and open the shell.process and open the shell.

9. Internal Morphology 3:Internal Morphology 3:
As the diductor muscles As the diductor muscles
relax the adductor muscles relax the adductor muscles
contract and close the shell.contract and close the shell.
Role of the Role of the lophophorelophophore is to is to
act as a feeding device, act as a feeding device,
which collects suspended which collects suspended
particles.particles.
Some brachiopods like Some brachiopods like
spiriferids have a spiral spiriferids have a spiral
calcite support called a calcite support called a
lophophore support or lophophore support or
spiralia.spiralia.
Draw diagram d on page Draw diagram d on page
137.137.

10. Internal morphology 4:Internal morphology 4:
On the diagram you can see On the diagram you can see
that the brachiopod has that the brachiopod has
TEETHTEETH (pedicle valve) and (pedicle valve) and
SOCKETSSOCKETS (brachial valve). (brachial valve).
What do you think the role of What do you think the role of
these are?these are?

11. Articulate Brachiopod Orders:Articulate Brachiopod Orders:
There are 7 orders. There are 7 orders.
(including Productids).(including Productids).
For each draw a simple For each draw a simple
diagram.diagram.
Make a note of the type Make a note of the type
of hinge line:of hinge line:
Long orLong or
ShortShort

12. They tended to live in They tended to live in
shallow marine conditions shallow marine conditions
(up to 500 m but may go (up to 500 m but may go
down to 6, 000m).down to 6, 000m).
Modern forms live in cool - Modern forms live in cool -
temperate waters around the temperate waters around the
Pacific (Japan, S. Australia, Pacific (Japan, S. Australia,
New Zealand, N. Atlantic New Zealand, N. Atlantic
and W. Scotland).and W. Scotland).
As there are modern day As there are modern day
equivalents we know their equivalents we know their
environments and so they environments and so they
are good palaeoenvironment are good palaeoenvironment
indicators (indicators (index fossilsindex fossils).).

13. Index fossils etc.Index fossils etc.
Define an index fossil:Define an index fossil:
A fossil that is restricted to a A fossil that is restricted to a
particular particular
palaeoenvironment.palaeoenvironment.
Corals mare perhaps the Corals mare perhaps the
best index fossils.best index fossils.
The most common The most common
question regarding question regarding
Brachiopods is how to tell Brachiopods is how to tell
the difference between the difference between
them and Bivalves.them and Bivalves.
We will cover this next when We will cover this next when
we look at Bivalves.we look at Bivalves.

14. Brachiopods are a long-lived Brachiopods are a long-lived
Phylum ranging from the Phylum ranging from the
Cambrian to Present.Cambrian to Present.
They were very common in They were very common in
the Palaeozoic and slightly the Palaeozoic and slightly
less so in the Mesozoic but less so in the Mesozoic but
still remain important.still remain important.
In the Present not many In the Present not many
forms are left with forms are left with
approximately 70 Genera.approximately 70 Genera.
Over 2500 fossil Genera are Over 2500 fossil Genera are
known.known.
The largest were found in The largest were found in
the Cambrian (370 mm).the Cambrian (370 mm).