Carnivory and herbivory
Capture and ingestion: teeth, mouthparts
Snail teeth: odontophore
Gut tubes: assembly-line processing
Carnassial teeth
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The shearing (scissor-like) action of carnassial teeth in modern carnivores is
generated when the inner surface of the fourth upper premolar (blue) passes outside
the outer surface of the first lower molar (red). This upper and lower-jaw tooth
combination is characteristic of both feliform (cats) and caniform (dogs) carnivores,
and is thus a synapomorphy* for these groups.
Carnassial teeth in a sabretooth
cat (Smilodon)
The shearing (scissor-like)
force of the carnassials acts to
create shear strain in bones.
The cusps of the upper and
lower teeth are shaped to
cradle and contain any roll of
the cylindrical bone; the shear
forces of the closing jaws,
delivered from above and
below, should be offset
transversely, i.e., the teeth
don’t line up on each other,
just as the cutting blades of
scissors are offset.
*From Wikkipedia: a synapomorphy is a trait shared
by two or more taxa (in this case families of cats and
dogs) and their most recent common ancestor whose
own ancestor does not possess the trait. So the
common ancestor of cat and dog families had
carnassials but not its ancestor.
From web: Steven M. Carr
Though it seems odd to refer to canine (dog) teeth in the cat family, and other non-dog
families, it is the huge canines that give the sabre-tooth cats their notoriety. The way
these teeth worked in bringing down prey has been an ongoing subject of debate. Papers
to read (courtesy of Kendra Lahut) offer some thoughts on how Smilodon used its canine
teeth
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McHenry, C.R. 2007. Supermodeled sabercat, predatory behavior in Smilodon fatalis
revealed by high-resolution 3D computer simulation. Proceedings of the National
Academy of Sciences USA 104: 16010: 16015.
Christiansen, P. 2007. Comparative bite forces and canine bending strength in feline
and sabretooth felids: implications for predatory ecology. Zoological Journal of the
Linnean Society 151: 423-437.
Narwhal whale
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The narwhal is a medium-sized (body length 45 m) toothed whale living in the Canadian Arctic
and Greenland waters. Males have a long,
straight, helical tusk, an incisor tooth modified
and extending asymmetically from the upper
left jaw, 2-3 m long. The species feeds on
bottom-living fish, e.g, halibut, at depths of up
to 1500 m under dense pack ice. These whales
are remarkably able deep divers: 800 – 1500
metres!
The tooth that is modified into a tusk is not
used to help obtain food. A female narwhal has
a shorter, and straighter tusk.
Pictures taken from web
Excluding seeds and fruits herbivory
on green tissue of plants is
characteristic of three large groups of
animals: gastropods, Orthoptera
(grasshoppers and allies) and
ruminant tetrapods.
Gastropoda:
phylum Mollusca:
snails are
examples of a
microphagous
herbivores
In the mouth region of a gastropod
there is a skeletal element, a plate
called the odontophore, that acts as
backing for a ribbon of horny (keratin)
teeth, the radula. The odontophore is
a very mobile skeletal element and can
be protruded far out through the mouth
of a snail; this deployment involves
antagonistic protractor and retractor
muscles.The odontophore can be
applied against substrate (rocks, coral
heads, aquarium glass) that is covered
with greeh algae. The ribbon is then
pulled to and fro by muscle antagonists
and slips over the edges of the
odontophore. The radula, a ribbon of
‘emery cloth’, rasps off algae as the
radula retracts and the alga is ingested
by the snail.
Teeth of the radula of gastropods
are species diagnostic
Pictures from the web