12
Y. J. WELLS
learning other discriminations (see Section B, p. 16) appear to abolish
altogether the capacity to learn to leave crabs alone (Boycott and
Young, 1958). It would be nice to know whether this is merely due to
long experience of good meals in the past, or because the response to
crabs is truly innate. Octopus vulgaris, unfortunately, has very small
pelagic larvae and while the responses of the related 0. briareus Robson
are potentially studiable from the moment of hatching, the animals
have not so far been observed to attack (Messenger, 1963).
Sepia has proved more amenable to study. This animal lays large
eggs, and the newly hatched young settle at once to bury themselves
in the sand, whence they emerge, apparently just like adults, to attack
n
5 A REWARDED FOR B NOT REWARDED c STARVED FOR 5 DAYS
(12 SEPIA)
THEN AS A c21 SEPIA)
ATTACKING
FOR ATTACKING
BEFORE I S 1 TRIAL
f? 5 0
2
w
2o
E 1 0
Z
4 0
30
I0 2 4 6 8 1 0
0 2 4 6 8 1 0
NUMBER OF PREVIOUS ATTACKS (ONE PER DAY)
FIG. 7. Mean times taken to attack mysids in successive trials with young S e e .
The animals, newly-hatched in the laboratory, had never seen prey before the start
of the experiment. The cuttlefish in the " B " series attacked but did not get
mysids shown in a glass tube. It appears that the action of attacking is selffacilitating. (From Wells, 1968.)
moving prey. Naive Sepia will attack mysids, and occasionally models
more or less like these. With further attacks the delay between observstion and attack decreases, suggesting learning by experience. But at the
same time the range of small moving objects attacked increases,
suggesting that the action of attacking is in some way self-facilitating,
so that the threshold for the response falls independently of learning
anything from experience of which objects proved edible (Fig. 7).
Within the first week or two of hatching Sepia appears to be virtually
untrainable, a finding that is interesting because it is associated with the
relatively slow post-embryonic development of the vertical lobe of the
supraoesophageal brain, a part known from lesion experiments to be
intimately concerned in visual learning (Wells, 1962b; see also IIB
Y. J. WELLS
learning other discriminations (see Section B, p. 16) appear to abolish
altogether the capacity to learn to leave crabs alone (Boycott and
Young, 1958). It would be nice to know whether this is merely due to
long experience of good meals in the past, or because the response to
crabs is truly innate. Octopus vulgaris, unfortunately, has very small
pelagic larvae and while the responses of the related 0. briareus Robson
are potentially studiable from the moment of hatching, the animals
have not so far been observed to attack (Messenger, 1963).
Sepia has proved more amenable to study. This animal lays large
eggs, and the newly hatched young settle at once to bury themselves
in the sand, whence they emerge, apparently just like adults, to attack
n
5 A REWARDED FOR B NOT REWARDED c STARVED FOR 5 DAYS
(12 SEPIA)
THEN AS A c21 SEPIA)
ATTACKING
FOR ATTACKING
BEFORE I S 1 TRIAL
f? 5 0
2
w
2o
E 1 0
Z
4 0
30
I0 2 4 6 8 1 0
0 2 4 6 8 1 0
NUMBER OF PREVIOUS ATTACKS (ONE PER DAY)
FIG. 7. Mean times taken to attack mysids in successive trials with young S e e .
The animals, newly-hatched in the laboratory, had never seen prey before the start
of the experiment. The cuttlefish in the " B " series attacked but did not get
mysids shown in a glass tube. It appears that the action of attacking is selffacilitating. (From Wells, 1968.)
moving prey. Naive Sepia will attack mysids, and occasionally models
more or less like these. With further attacks the delay between observstion and attack decreases, suggesting learning by experience. But at the
same time the range of small moving objects attacked increases,
suggesting that the action of attacking is in some way self-facilitating,
so that the threshold for the response falls independently of learning
anything from experience of which objects proved edible (Fig. 7).
Within the first week or two of hatching Sepia appears to be virtually
untrainable, a finding that is interesting because it is associated with the
relatively slow post-embryonic development of the vertical lobe of the
supraoesophageal brain, a part known from lesion experiments to be
intimately concerned in visual learning (Wells, 1962b; see also IIB