CONTENT :
INTRODUCTION
MODE OF LIFE
MORPHOLOGY 1
MORPHOLOGY 2
MORPHOLOGY 3
MORPHOLOGY 4
MORPHOLOGY 5
INTERNAL FEATURES
INTERNAL MORPHOLOGY 2
INTERNAL MORPHOLOGY 3
INTERNAL MORPHOLOGY 4
GEOLOGICAL HISTORY
CONCLUSION

Phylum: Brachiopoda
Classes:Articulata
 Inarticulata
Orders: 7 Articulate
 4 Inarticulate

Brachiopod
Brachiopods
(brachio=arm; pod
= foot)
valves are opened
and closed by
contracting muscles
called adductor and
diductor muscles.

Mode of Life
Brach sessile and marine
Attached to seafloor by pedicle
at posterior
Inarticulate brachs live in tube
Adult brachiopods are filter
feeders
Filter food particles from water
Food passes from mouth to the
esophagus to stomach
Animals feeding on brachiopods
include starfish, crustaceans,
gastropods, and fish.

They have 2 VALVES
(shells) that totally enclose
the soft parts.
The average size is 20 - 70
mm but can range up to 370
mm.
The valves can open and are
hinged at one end; muscles
open and close the shell.

 Modified from Clarkson (1986)
clam

Morphology 2
They usually allow water into
the shell, as they are filter
feeders extracting food from
seawater.
The two valves are different
in size (as opposed to
bivalves).
However; they do show a
line of lateral symmetry
along the middle of the
organism.

Morphology 3:NaMiNg of the
valves
The smaller valve is the
BRACHIAL valve (upper in
life position).
The larger valve is the
PEDICLE valve (lower in life
position).
The animal secretes the
valves as it grows, the
original small shell is called
the UMBO and the shell
grows outwards from either
side of this point.

Morphology 4:
 Often the pedicle valve has a
small circular opening
(FORAMEN) at the end
through which a type of foot
extends called the PEDICLE.
The pedicle allows the
brachiopod to attach itself to
the sea floor.
Inside the shell the body fills
much of the body cavity.

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

 The inside of the shell is the
MANTLE CAVITY and is mainly
the LOPHOPHORE, which is a
food gathering and water-filtering
device.
The important muscles are:
 At the posterior end is the
pedicle “foot” type of
ligament/muscle which when
extended could usually reach
outside of the shell.
 The main muscles were the
ADDUCTOR and DIDUCTOR
muscles, which were used to
close the shell.

Internal morphology 2:
Both sets of muscles
were attached to the
shell and although not
preserved in the fossils
there are scars left from
where the muscles were
attached to the shell.
The CARDINAL
PROCESS and HINGE
acts as a fulcrum on
which the muscles can
pull.
The diductor muscles
contract and pull down
the cardinal process and
open the shell.

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

Internal morphology 4:
On the diagram you can see
that the brachiopod has
TEETH (pedicle valve) and
SOCKETS (brachial valve).

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

CONCL
USION
 Brachiopods are exclusively marine
Live in environments ranging from subtidal to the
abyss
Brachiopods swim only during larval stage
Widespread distribution reflects free-swimming
larval stage
Brachiopods occur throughout the world in both
cool and temperate waters (Japan, S. Australia, and
New Zealand).
Most brachiopods found in the neritic zone (waters
over the continental shelf), a few are found depths
of 5000 m
Most brachiopods range between 20 and 70 mm, some
are up to 370 mm.