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CONTRIBUTIONS FROM THE BERMUDA BIOLOGICAL STATÏON
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FOR RESEARCH, NO. 31.
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THE LOCOMOTION on
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BY G. H. PARKER.
The Chiton tuberculatus of the Bermuda Islands affords excellent
for the study of gastropod locomotion.
In specimens eight
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centimeters long, thefoot measures about six centimeters in length
f
and two in breadth.
Like other species of the genus, this chiton ‘
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exhibits a…retrograde wave—movement on its foot (Vlès, 1907), in
that the locomotor waves run from anterior to posterior. . As a rule
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a wave appears at the anterior end of the foot before the preceding
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one has disappeared at the posterior end; hence the foot may exhibit
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at any moment one or two waves in progress.
Each wave traverses
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the foot
tWenty to thirty seconds.
The waves extend the
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Whole width of the foot and are from ve to six millimeters in antero—
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posterior extent.
They represent an area of the foot temporarily
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lifted from the substrate.
This can be easily seen in a chiton creeping ;
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on a glass plate in the air. Under such circumstances each wave
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marked by an area of air which runs under the foot as the wave begins
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to form at the anterior end and continues with it until it has disap—
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peared posteriorly. Excepting in the region of the wave, the foot is
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rmly
attached to the substrate; hence at any moment from mue—
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Ï
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tenths
to four fths of the foot is xed and the remainder free.
On the
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'Stallcc of the foot is moved forward as much as ve millimeters f01
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each wave. ’This, as'I have elsewhere pointed out (Parker, 1911,
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essential 'act in this type of locomotion and is
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of all creepii1g gastropods.
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Of the two methods found in gastropods for attachirig the foot toth€:
"substrate, adhf3810nby
and suction, chiton depends almost