SPAWNING OF THE OCTOPUS.
The first instance of the octopus spawning in an aquarium in this
country occurred at Brighton on the 19th of June, 1873. A large
female octopus, caught at Dieppe, was brought in on the 26th of
the preceding April, and, immediately on her arrival, a fine male
previously received from Mevagissey conceived a liking for her, and
evidently rejoicing in the good fortune which had provided for him
a suitable mate, paid her such assiduous court, that his addresses
were quickly accepted. It was a case of “love at first sight,” and
in three days the captive damsel was wooed and won. The event above
mentioned was, therefore, not unexpected. Our octopus, fortunately
selected as a suitable site for her nest, a recess in the rock-work,
close to the front glass of the tank, so that her movements could
be easily observed. Her body just filled the entrance to it, and
she further strengthened its defences by dragging to the mouth of
her cavern two dozen or more of living oysters, and piling them one
on another to form a breast-work or barricade, behind which she
ensconced herself. Over this rampart she peered with her great,
sleepless, prominent eyes; her two foremost arms extended beyond it,
their extremities coiling and writhing in ceaseless motion, as if
prepared to strike out right and left at any intruder. She seemed
never to be taken unawares, and was no more to be caught napping than
a cunning middy “caulking it” in the middle watch. Couchant, and on
the “look-out,” like Sir Edwin Landseer’s lions, she barred with her
body the passage to her den, ready to defend it against all foes.
Her companions evidently felt that it was dangerous to approach an
excited mother guarding her offspring, and none ventured to go within
arm’s length of her. Even her forlorn husband was made to keep his
distance. If he dared to approach with intent to whisper soft words
of affection into his partner’s ear, or to look with paternal pride
on the newly-born infants, the lady roused herself with menacing
air, and slowly rose till her head over-topped the barrier; by an
instantaneous expansion of the pigment vesicles of the skin, a dark
flush of anger tinged the whole surface of the body; the two upper
arms were uncoiled and stretched out to their utmost length towards
the interloper; and the poor snubbed, hen-pecked father, finding
his nose put out of joint by the precious baby, which belonged as
much to himself as to its fussy mother, invariably shrank from their
formidable contact, and sorrowfully and sullenly retreated, to muse,
perhaps, on the brief duration of cephalopodal marital happiness. All
his fellows in the tank knew that he was in bad humour, and took care
to keep out of his way. As soon as they saw him coming towards them
they gathered their arms close together in a straight line, and swam
off rapidly, tail first, to the further side of the tank.
[Illustration: Fig. 6. Eggs of the Octopus. (_O. vulgaris_)]
The eggs of the octopus, when first laid, are small, oval,
translucent granules, resembling little grains of rice, not quite an
eighth of an inch long. They grow along and around a common stalk,
to which every egg is separately attached, as grapes form part of
a bunch. Each of the elongated bunches is affixed by a glutinous
secretion to the surface of a rock or stone (never to seaweed, as has
been erroneously stated), and hangs pendent by its stalk in a long
white cluster, like a magnified catkin of the filbert, or, to use
Aristotle’s simile, like the fruit of the white alder. The length and
number of these bunches varies according to the age and condition of
the parent. Those produced by a young octopus are seldom more than
about three inches long, and from twelve to twenty in number; but a
full-grown female will deposit from forty to fifty of such clusters,
each about five inches in length. I have counted the eggs of which
these clusters are composed, and find that there are about a thousand
in each: so that a large octopus produces in one laying, usually
extended over three days, a progeny of from 40,000 to 50,000. Our
brooding French octopus, when undisturbed, would pass one of her arms
beneath the hanging bunches of her eggs, and dilating the membrane on
each side of it into a boat-shaped hollow, would gather and receive
them in it as in a trough or cradle, exhibiting in its general shape
and outline a remarkable similarity to those of the argonaut, or
“paper-nautilus,” with the eggs of which octopod its own are, as I
have already explained, almost identical in form and appearance.
Then she would caress and gently rub them, occasionally turning
towards them the mouth of her flexible exhalent and locomotor-tube,
like the nozzle of a fireman’s hose-pipe, so as to direct upon them
a jet of the excurrent water. I believe that the object of the
syringing process is to free the eggs from parasitic animalcules,
and possibly to prevent the growth of conferva, which I have found
rapidly overspread those removed from her attention. Week after week,
she continued to attend to them with the most watchful and assiduous
care, seldom leaving them for an instant except to take food, which,
without a brief abandonment of her position, would be beyond her
reach. Aristotle asserted that while the female is incubating she
takes no food. This is incorrect.
In the tank with our specimen were seven others of her species, and
to supply them with food about five-and-twenty living shore crabs
(_Carcinus mænas_) were daily tossed into it. Although she so seldom
left her nest, she generally obtained her share of these, and would
seize with her suckers, and draw towards her, sometimes, three at a
time, one by each of three of her arms. Their shells were soon broken
and torn apart by her powerful beak, and when she had devoured the
contents the hard _débris_ was cast out of her den.
But although the old naturalist of Stageira was mistaken in supposing
that the female octopus does not take food during the period of the
development of her ova, he was right in believing that her anxiety
for her progeny, and her unremitting care of them, tell injuriously
upon her health. A brooding octopus shows signs of diminished
bodily vigour, as a sitting hen bird loses flesh whilst hatching
her eggs. Her respiration at times becomes laboured. When the water
is inhaled (I use the word intentionally, for the animal _breathes_
the oxygen contained in it) at the open part of the mantle-sac, the
siphon-tube, at its orifice, is often drawn forcibly inward; and when
the pair of bellows of the body close, the same opening of the tube
is distended to its fullest capacity by the out-rush of the exhaled
water. Repeated observations have shown that it not unfrequently
happens that the vital powers of the octopus are so exhausted by her
protracted maternal cares that she dies when relieved by the hatching
of her eggs from the necessity of further vigils. Many also die in
the act of spawning, or when distended with ova.
To return to our mother octopus at Brighton,—at the end of the fifth
week from the deposit of her ova she began to exhibit considerable
irritation and restlessness, in consequence of the annoyance she
experienced from visitors trying to rouse her to movement, or to
frighten her from her eggs, by knocking at the glass with coins
or sticks, and flouting pocket-handkerchiefs in front of her. I
found that on some of these occasions, in her excitement, whilst
protecting her eggs from the supposed danger, she had torn away the
lower portion of some of the clusters, and that their number was
considerably diminished. It therefore became necessary to screen
her from the public gaze. Fearing also that, notwithstanding the
cessation of the interruption to which she had been subjected, she
might by her over-fussiness destroy the remainder; or that even if
her progeny were safely born, they might hatch out unperceived, and
thus our hopes be frustrated and an important observation lost,
I decided on removing some of them from the exhibition tank, and
placing them in a smaller one in the laboratory, where they could be
closely watched. The water was therefore run off till a depth of only
about six inches remained; and one of the catkin-like bunches of eggs
was carefully detached. To do this neatly, without disturbing the
other clusters, was not so easy as it might be supposed; for not only
did the hen octopus guard the entrance to her recess, and require
careful handling, but the old male also was pugnacious. As soon as
he espied his keeper in the tank, he strode forth from his corner
towards him, looking exceedingly savage, and making a demonstration
of attack which would have frightened a novice, and led a looker-on
to believe that the intruder was about to be the centre figure in
a Laocoon group of writhing, twining octopods, and to suffer the
fate of _Clubin_, or to escape only after a terrible combat, like
_Gilliatt_, in M. Victor Hugo’s novel. But the old fellow’s bark was
worse than his bite, for on a bare arm being presented to him in the
shallow water, he made no attempt to hold or bite it, but merely
scrambled and crawled harmlessly over it.
By the removal of a portion of these eggs I hoped, also, that an
interesting question concerning their development might be finally
answered. Aristotle had been understood to affirm that the parent
octopus “incubates” her eggs. I had always expressed very decidedly
my opinion, derived from previous experiments on the eggs of the
cuttle-fish and squid (_Sepia_ and _Loligo_) that, the ova once
impregnated, no incubation by the parent is required or takes place
in a sense equivalent to that of a fowl developing a chick by the
warmth of its body; but that her unremitting attention to them is
solely for the purpose of protecting them from injury, keeping them
free from animal and vegetable parasites, and preventing their being
devoured by fishes, or members of her own tribe—possibly by their own
father. If I had felt myself free to act according to my inclination,
I should, at once, have removed a larger number of the eggs; but in
matters concerning which nothing is positively known, and everything
has to be learned, caution is requisite. There was good reason
for hesitation, when care in the conduct of the observation might
remove the doubts of centuries. The first thing to be ascertained
was—Had the ova been properly fecundated—did they contain, each,
a living embryo? The microscope answered “Yes.” Under a low power
a young octopus was seen moving freely in the fluid contained in
each transparent granule, the bright orange-brown colour in the
pigment cells of its skin flashing, dying out, and re-appearing in
another place, like sparks in tinder. And I was astonished to see
that the little creature within the unbroken membrane was already
endowed with the power of assimilating its colour to that of its
surroundings. When light was reflected upon its surface, and through
its translucent body, from a piece of white paper laid on the mirror
of the instrument, it became pallid and colourless: on a bronze
penny being substituted for the paper, it assumed a darker hue; and
(which was still more remarkable) on its being disturbed by a slight
compression or agitation of the egg, its surface became suffused with
the red flush of anger and irritation which characterises the adult
under provocation.
It having been seen that many of the eggs left in their original
position had been bruised by the mother octopus, and that there were
black marks on the stone beneath them, betokening the presence of
decomposition, I was anxious to remove the remainder from her; but,
for the reason above mentioned, amongst others, I considered it
would be prudent to assure myself that the eggs transferred to the
smaller tank retained their vitality. Seeing, at the expiration of
four days, that the young animals within them were as lively as ever,
and progressing so rapidly that their escape from the egg might soon
be expected, I had the larger tank partly emptied again, for the
purpose of taking from the nest any that might still be uninjured. It
was found, however, that those which had not been torn away by the
parent had been squeezed by her between herself and the rock-work,
and were consequently dead, only a very few showing signs of having
been prematurely hatched by the violent rupture of the envelope.
She had overlain her babies. Those which were taken from her on the
forty-second day from their extrusion for special inspection, were
successfully hatched, and I do not doubt that if they could have been
kept clean and free from parasites this would have taken place if
they had been detached immediately after they were laid. The young
octopods made their appearance on the 8th, 9th, and 10th of August:
the eggs had been extruded on the 19th, 20th, and 21st of June, and
thus, although it was proved, as I expected, that the development of
the embryo does not depend on incubation, the accuracy of Aristotle’s
statement that its period in the egg is fifty days was completely and
satisfactorily confirmed.
In the first week of January, 1875, another brood of young octopods
was hatched in the Brighton Aquarium, and in this, as in the former
instance, the period of development was that assigned to it by
Aristotle. From observations made during the previous winter I did
not expect that maturity would be completed within this term. Two
“nestings” of octopus then occurred; and after twenty days, from time
to time, as opportunity offered, when the mother left them for a
minute in pursuit of an active crab scuffling away to the further end
of the tank, one of the clusters of eggs was removed, and suspended
in a separate cistern. The half-formed embryo was visible, though
motionless, within the membranous envelope; therefore it was evident
that the fertilisation of the ova had been effected. But although
the parent, in both cases, assiduously guarded them for nearly
three months—almost twice the, apparently, normal period—they were
addled, as were also those which had been detached from under her
care. It appeared to me probable that the vitality of the embryo was
destroyed in an early stage by the lower temperature of the water
during the winter months, but I was not without hopes that their
progress towards maturity might prove to be merely retarded by the
same influence,—an effect which is well known to be produced by cold
on the ova of the salmonidæ. In order to test this, some of the eggs
were placed in a tank in the warm boiler-house, but without any
beneficial results. Yet the brood referred to was hatched in water of
the same temperature as that in which the former ones were addled,
varying little from 54 deg. Fahrenheit. I am unable to account for
this; so I reserve my opinion of the cause of failure, and am content
to watch, and wait, and patiently note facts, and to abstain from
propounding theories on unsafe bases.
Everyone who loves and studies animals knows that each differs from
others of its species, in its habits and little ways, as distinctly
as children, and men, and women are diverse in character and
disposition. The horses you have owned, the dogs you have loved, your
cats, parrots, and even your pet cage-birds and little white mice,
have possessed widely varying characters and idiosyncrasies. Fishes,
the crustacea, and even the octopods are not excepted from this
individuality. The hen octopus in question, whilst on sentry duty
guarding her undeveloped progeny, assumed a position and attitude
totally different from that adopted by her predecessor in maternal
joys. The syringing of her eggs with a current of water from the
syphon tube was repeated by her; but she never cradled them, as did
the other, in the expanded membrane of a limb. Her usual posture
was with the under portion of her body presented to them, her eight
arms turned completely back, exposing their under surface armed with
their battery of suckers, the muzzles of the latter pointing in every
direction, and the tip of the hard, horny beak, just discernible.
The fine ends of the arms might sometimes be seen gently winding
amongst the clusters of eggs as tenderly and lovingly as a father’s
fingers through the tresses of a darling child, but there was no
evident nursing in this case.
An octopus about to spawn, like some birds in search of a
nesting-place, seeks the most retired nook she can find in which to
deposit her eggs. The elasticity of her body enables her to squeeze
herself through a very small orifice; and, therefore, the narrower
the entry to her den the more suitable is it for her purpose, because
the better adapted for defence against enemies and intruders. A
curious instance of the choice of such a nesting-place came under
my notice in March, 1874. Some fishermen, whilst dredging in the
Channel off Brighton, brought up an earthen jar or carboy, which
would hold about two gallons. It was covered with serpulæ, &c., and
was forthwith taken to the Aquarium. There it was discovered that it
contained an octopus and her eggs. The neck of the jar was only two
inches in diameter: the octopus was a fully-grown specimen.
The young octopus fresh from the egg is of about the size of a large
flea, and when irritated is of nearly the same colour. It is very
different in appearance from an adult individual of the same species.
At first sight it is more like a _sepia_, without its tentacles, than
an octopus. The arms, which will afterwards be four or five times
the length of its body, are so rudimentary as to be even shorter in
proportion than the pedal arms of the cuttle-fish, and appear only as
little conical excrescences, having points of hair-like fineness, and
arranged in the form of an eight-rayed coronet around the head.
At this early stage of its existence the young octopus seeks and
enjoys the light which it will, later in life, carefully shun. It
manifests no desire to hide itself in crevices and recesses, as the
adult does, but swims freely about in the water, often close to the
surface, propelling itself backward by a series of little jerks
caused by each stroke of the force pump, which expels a jet of water
from the out-flow pipe of the syphon. This contrast of its habits in
youth and age is so remarkable that when, after witnessing the gay
activity of the movements of the child-octopus, I again watched the
furtive, skulking habits of its shrivelled-skinned father, I could
not help comparing the latter with the old thief-trainer in “Oliver
Twist,” and wondering whether there ever could have been a time
in the life of Fagin the Jew when he was innocent and frolicsome,
and played, and leaped, and ran, and danced, and revelled in the
sin-exposing sunshine, ere the light of day became odious to him, and
he shrank from it as a danger to be dreaded, and kept himself hidden
in his den whilst his emissaries went out, like the arms of the old
octopus, in search of prey for the benefit of their employer.
I can say but little concerning the fertilisation of the eggs of the
octopidæ in a book intended for readers of all classes, but it is
so remarkable that this chapter would be incomplete without a few
words upon the subject. They are fecundated before, not after, their
extrusion. In the breeding season a curious alteration takes place in
one of the arms of the male octopus; according to Steenstrup, always
the third on the right side, although it has been stated that the
third arm on the left is sometimes the one thus affected. The limb
becomes swollen, and from it is developed a long, worm-like process,
furnished with two longitudinal rows of suckers, from the extremity
of which extends a slender, elongated filament. When its owner offers
his hand in marriage to a lady octopus she accepts it, _and keeps
it_, _and walks away with it_, for this singular outgrowth is then
detached from the arm of her suitor, and becomes a moving creature,
having separate life,[18] and continuing to exist for some time after
being transferred to her keeping. In the meanwhile the lost portion
of the “hectocotylized” arm of the male is gradually reproduced, and
in due time it assumes its former appearance.
The habits of the Eledone, of which there is only one British
species, _E. cirrosa_, are the same as those of _Octopus vulgaris_,
from which it chiefly differs in having only one row of suckers
instead of two along the under surface of its arms. Individuals of
this species have occasionally deposited a few eggs in the Brighton
Aquarium; but these have not, hitherto, arrived at maturity. They are
considerably larger than those of the octopus, and not so numerous.
The eledone is not so hardy as its relative, and, in captivity, the
female generally dies in spawning.
It is impossible for any student or observer of these animals to
avoid recognition of Aristotle’s wonderfully intimate knowledge of
their life-history, embryology, sexual conditions, and anatomy. When
I first saw the octopus guarding her eggs the thought immediately
rose in my mind,—“Aristotle must have had an aquarium!” He might
have learned by observations at the sea-side, on the coast of the
Mediterranean, the mode of progress of the octopus when swimming and
crawling, its change of colour when excited, the form of its eggs,
&c., which he has correctly described; but it is impossible that he
could have so exactly designated the duration of the existence of the
embryo in the egg without having had opportunities of noticing the
date of its extrusion, and that of the escape of the young octopods
by the rupture of the envelope. His mention of the remarkable sexual
development of one of the arms, its use in the impregnation of the
ova, their apparent incubation by the mother, and her incessant
attention to her charge, also indicates that, during the intervening
time, the male and the brooding female were continually under his
inspection. We are therefore led to the conclusion that the marine
aquarium, in some form, is one of the things that are not “new under
the sun.”