Phylum:Phylum: BrachiopodaBrachiopoda

Classes:Classes: ArticulataArticulata InarticulataInarticulata

   Orders:Orders: 7 Articulate 7 Articulate 4 Inarticulate4 Inarticulate

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.

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..

Morphology 3:Morphology 3:Naming of the Naming of the valvesvalves

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.

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.

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.

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-filtering food gathering and water-filtering device.device.

Draw diagram (d) from page Draw diagram (d) from page 125 Black.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.

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.

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 Draw diagram d on page 137.page 137.

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?

Articulate Brachiopod Articulate Brachiopod Orders: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

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).).

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.

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).