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OEB 130: Feeding mechanisms Part 2
Pharyngeal jaws and gill supports: structure and function
Lecture outline
• Brief review of the teleost fish head from last lecture
• Introduction to the Pharyngeal Jaw Apparatus
(PJA) in fishes
 anatomy and function of pharyngeal jaws
 relationship to gill arches and gills
 bony elements
 muscles that control the PJA
 snail crushing!
 the PJA of moray eels – amazing!
•
Filter feeding by fishes using modified gill arches
OEB 130: Feeding 3
Pharyngeal jaws: structure and function
NEXT TIME – feeding mechanism lecture #3
• Fishes with a third set of jaws!
The tongue-bite
mechanism in osteoglossomorph fishes
•
Shark jaws and feeding systems
• Techniques for experimentally studying the function
of the complex mechanical feeding systems in fishes
Key point today: most ray-finned fish have 2 sets of jaws:
oral jaws, and pharyngeal jaws
OEB 130: Feeding 3
No class Monday Feb. 15th – President’s day
Office Hours (and by appointment):
• Kelsey: M 2-3pm
• Dylan: W 2-3 pm
• George: F 1-2 pm
Location: MCZ Labs building, first floor, room 108;
Lauder Lab conference room;
through two sets of doors, and first door on the left
Brief review of the teleost fish skull from last lecture
Brief review of the teleost fish skull from last lecture
Epinephelus niveatus, photos by Karsten Hartel
Schematic diagram
Mechanical linkages and major elements of the fish skull
Levator
operculi
Epaxial
muscles
Levator
operculi
Levator
arcus
palatini
Water in
front of
mouth
Adductor
arcus
palatini
BUCCAL
CAVITY
Hypaxial
muscles
Geniohyoideus
Sternohyoideus
OPERCULAR
CAVITY
Water in
front of
mouth
Muscles
Oral jaws
Ligaments
Hyoid
apparatus
Neurocranium
Pectoral
girdle
Suspensorium
BUCCAL
CAVITY
Hyoidmandibular
ligament
Branchiostegal
apparatus
Opercular
apparatus
Operculomandibular
ligament
OPERCULAR
CAVITY
Water exits opercular openings
(between operculum and pectoral
girdle).
Brief review of the teleost fish skull from last lecture
neurocranium
Ascending
process
eye
operculum
Pectoral
girdle
(nasal bone)
suspensorium
Premaxilla
maxilla
mandible
Jaw joint
hyoid
Pectoral
fin
Inside the fish head: the gill arches and the
pharyngeal jaw apparatus (PJA)
Pharyngobranchial 1
The 5 gill arches on each
side form a “basket” :
the branchial (gill) basket
Gill arches
(usually 5 pairs,
#5 is incomplete)
Neurocranium
1
2 3 4
5
Premaxilla
Lower jaw
Basihyal
(“tongue”)
Hyoid
Urohyal – part of the hyoid
embedded in the sternohyoideus muscle
Side view of a perch skull, with the left side suspensorium and opercular
series removed to show the pharyngeal jaw apparatus
Pectoral
girdle
Brief review of the teleost fish skull from last lecture
neurocranium
Ascending
process
eye
operculum
Pectoral
girdle
(nasal bone)
suspensorium
Premaxilla
maxilla
mandible
Jaw joint
hyoid
Pectoral
fin
View into mouth cavity from behind looking forward
UPJ
Gill arches
(usually 5 pairs)
LPJ
LPJ: Lower pharyngeal jaw
UPJ: Upper pharyngeal jaw
Close view to show the PJA
UPJ
LPJ
LPJ: Lower pharyngeal jaw
LPJ
UPJ: Upper pharyngeal jaw
Virtual dissection through a fish head
to show the internal pharyngeal jaws
3D CT scan movie of
a teleost fish
showing the head
skeleton – the upper
and lower pharyngeal
jaws are visible in the
“throat” area.
Virtual dissection through a fish head
to show the internal pharyngeal jaws
3D CT scan movie of
a teleost fish
showing the head
skeleton – the upper
and lower pharyngeal
jaws are visible in the
“throat” area.
Schematic 3D diagram of the pharyngeal jaw apparatus
Inside the fish head: the gill arches and the
pharyngeal jaw apparatus (PJA)
Pharyngobranchial 1
The 5 gill arches on each
side form a “basket” :
the branchial (gill) basket
Neurocranium
Gill arches
(usually 5 pairs)
1
2 3 4
5
Premaxilla
Lower jaw
Basihyal
(“tongue”)
Hyoid
Urohyal – part of the hyoid
embedded in the sternohyoideus muscle
Side view of a perch skull, with the left side suspensorium and opercular
series removed to show the pharyngeal jaw apparatus
Pectoral
girdle
More realistic drawings of the pharyngeal jaw apparatus (PJA)
PB 2
Epibranchial 1
Upper
pharyngeal
jaw
PB 3
PB 4
Hyoid
1 2
3 4
Hyoid
5
Hyoid
Ceratobranchial 5 =
lower pharyngeal jaw
Basihyal
(“tongue”)
Epibranchial 1
Pharyngobranchial 1
Dorsal view of the gill arches and PJA in a teleost fish. The dorsal gill arches on the
right side have been reflected back to show the underside (ventral side).
Another schematic diagram of the pharyngeal jaw apparatus
The gill arches have been
removed from this schematic
diagram, and only a few of the
muscles are shown.
Diversity of the lower pharyngeal jaw
2 lower pharyngeal jaws
fused into one plate
and covered in
molariform teeth
2 lower pharyngeal jaws =
2 ceratobranchial 5 bones,
a left and a right, closely attached to each other
Bluegill sunfish with a snail held in the pharyngeal jaws
The Pharyngeal Jaw Apparatus (PJA)
are the “throat jaws” in fishes
which are modified tooth plates from
the gill arches, are used to manipulate
shred, crush prey, and for swallowing,
and have an array of muscles that
allow precisely controlled
movements of the jaws.
Oral jaws, or
Front jaws, or
Mandibular Jaw
Apparatus (MJA)
PJA
Image based on an x-ray movie
Location of the pharyngeal jaw apparatus (PJA) and use of hydraulic
transport to move a snail captured by suction into position between the upper
and lower pharyngeal jaws. Images from x-ray movie.
Pumpkinseed sunfish crushing a snail with the PJA
Snail before
encountering the PJA
Snail after
encountering the PJA
The remarkable “raptorial” pharyngeal jaws of moray eels:
amazingly mobile pharyngeal jaws
Mehta, R. S. and Wainwright, P. C. (2007). Raptorial jaws in the throat
help moray eels swallow large prey. Nature 449, 79-82.
The remarkable “raptorial” pharyngeal jaws of moray eels
UPJ
esophagus
LPJ
The remarkable pharyngeal jaws of moray eels
UPJ
UPJ
LPJ
Pharyngeal jaw apparatus of
moray eels (top),
and a close SEM view of the
teeth (below)
LPJ
The remarkable “raptorial” pharyngeal jaws of moray eels
The remarkable “raptorial” pharyngeal jaws of moray eels
The remarkable “raptorial” pharyngeal jaws of moray eels
The remarkable pharyngeal jaws of moray eels
More details of how this works
if you are interested.
Caption to this figure on the
next slide
Caption to previous figure
GILLS, GILL RAKERS, AND SUSPENSION FEEDING
Pharyngobranchial 1
1
2 3 4
5
Premaxilla
Lower jaw
Basihyal
(“tongue”)
Hyoid
Urohyal – part of the hyoid
embedded in the sternohyoideus muscle
Side view of a perch skull, with the left side suspensorium and opercular
series removed to show the pharyngeal jaw apparatus
Pectoral
girdle
Inside the fish head: the gill arches,
shown with gills and the gill rakers
Gill filaments
gill arch
Gills, gill rakers, and suspension feeding
Sanderson, S. L. and Wassersug, R. (1990). Suspension-feeding vertebrates. Sci. Amer. 262, 96-101.
Gills, gill rakers, and suspension feeding
Gill rakers are usually made of
bone, but can be short and stubby
and largely connective tissue too.
Water flow
Gill rakers
Gill filaments
Gills, gill rakers, and suspension feeding
Sanderson, S. L. and Wassersug, R. (1990). Suspension-feeding vertebrates. Sci. Amer. 262, 96-101.
Sanderson, S. L. et al. (2001). Crossflow filtration in suspension-feeding fishes. Nature 412, 439-441.