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Molting
Crabs molt
more often when they are small an less
often as they grow.
The result
of each molt is typically a 25%-40%
increase in
carapace width.
The
pictures to the right show the stages of
the molting process.
<double
click on any image to enlarge>
When a
blue crab is ready to molt it is known
as a "peeler" crab.
When it
starts to molt, the crab cracks the back
of the shell between the carapace and
the abdomen.
The crab
then slowly backs out. It is then in a
soft-shell condition. This is also
called "busting".
The time
to complete this phase varies, but can
take about 2 to 3 hours to complete the
molt.
After
shedding its old shell, the crab expands
by pumping water into its body and the
new shell begins to form.
The
soft-shell crab is very vulnerable to
predators (including other crabs) and
hide in rocks, aquatic vegetation (SAV)
or bury in mud or sand.
Within a
few hours after molting, the new shell
begins to harden. After about 12
hours the shell is slightly stiff and
the crab is referred to as a
papershell.
After
another 12 hours, the shell becomes
harder, yet still pliable and is
referred to as a
buckram.
The total
process of molting takes about three to
four days to complete resulting in a
(bigger) hard shell crab.
Without
its old hard shell (which, is called a
"slough" when it is discarded), the crab
is now temporarily a soft-shelled crab.
The new exoskeleton is there, but it is
still very soft.
Another
image of a blue crab molting
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