436 
Locomotion 
Observations made on live individuals in an 
aquarium revealed a most interesting locomo- 
tory pattern. Although most octopods, with the 
exception of the pelagic species such as Cirro- 
teuthis, move about principally by two meth- 
ods, "crawling” and rapid ejection of water 
from the siphon, the flapjack devilfish, owing 
to its unusual anatomical features, is not able 
to move effectively by these means. The very 
weak suckers and the loss of free arm move- 
ment due to webbing prevent crawling; and 
the reduction in the mantle aperture consequent 
to the posterior placement of the siphon greatly 
decreases the effectiveness of the siphon as a 
locomotory organ. 
The principal means of progression, as ob- 
served in the aquarium, was by opening and 
closing of the webbed "umbrella” together with 
fin movement. The general pattern of this 
method of locomotion, which was analogous to 
that of a jellyfish, is seen in Figure 3 a-f. 
From a resting state the animal initiated 
movement by extreme opening of the um- 
brella (Fig. 3 b) . This caused the oral surface 
to take on a convex shape with the arms 
curved slightly upwards and anteriorly. Fol- 
lowing this, the umbrella was closed by a 
PACIFIC SCIENCE, Vol. XIX, October 1965 
powerful downward stroke, which reduced the 
opening into the concavity of the now closed 
umbrella to about one-half the diameter of the 
animal (Fig. 3c). This action forced the ani- 
mal off the bottom by (1) the actual contact 
of the downward thrusting arms with the bot- 
tom and ( 2 ) the interaction of the closing oral 
surface with the water. This pattern of opening 
and closing the umbrella was repeated so that 
the animal remained off the bottom. The clos- 
ing action was about twice as rapid as the open- 
ing. With each stroke the devilfish would move 
from 4 to 12 inches depending on the thrust of 
the closing stroke, and the tempo and direc- 
tion of movement. The swimming motion was 
observed to progress as rapidly as one stroke 
every two seconds, although the usual tempo 
was once every four seconds. With movement 
at the higher rate the animal was carried to the 
surface of the aquarium in three to four strokes. 
Subsequent to termination of swimming, the 
animal opened its umbrella into the convex 
shape, thereby descending slowly (Fig. 3 /). 
When swimming the animal occasionally made 
partial strokes instead of complete ones. 
With contraction of the umbrella a jet of 
water was ejected from the siphon (Fig. 3 c). 
This jet could be directed by the siphon left 
TABLE 4 
Stomach Contents of Eight Opisthoteuthis califomiana Collected in the Northeast Pacific 
DATE 
DEPTH 
(fathoms) 
LOCATION 
ANIMAL 
SIZE (mm) 
STOMACH 
vol. (ml) 
CONTENTS 
5-14-61 
425 
Gulf of Alaska 
350 X 340 
<1 
crustacean remains including 1 
amphipod; some sand grains 
7-3-61 
425 
off north 
Oregon coast 
255 X 250 
<1 
nothing which could be made out 
12-11-61 
335 
off north 
Oregon coast 
420 X 380 
empty 
12-11-61 
375 
off north 
Oregon coast 
280 X 260 
2 
crustacean remains; 3 mysids approx. 
7 mm long 
12-11-61 
375 
off north 
Oregon coast 
340 X 330 
4 
8 mysids, largest 10 mm; 4 amphi- 
pods, 9 copepods, 2 isopods, 1 
crangonid or hippolytid shrimp 
approx. 22 mm 
3-7-62 
425 
off north 
Oregon coast 
190 X 180 
1 
crustacean remains, mostly copepods 
3-7-62 
425 
off north 
Oregon coast 
210 X 150 
3 
same as above plus partly digested 
polychaete? 
8-30-62 
250 
off north 
Oregon coast 
250 X 240 
1 
crustacean remains, mostly copepods 
