The Steamer Is Able To Dive Only
To A Very Short Distance.
It feeds entirely on shell-fish
from the kelp and tidal rocks:
Hence the beak and head, for
the purpose of breaking them, are surprisingly heavy and
strong: the head is so strong that I have scarcely been able
to fracture it with my geological hammer; and all our sportsmen
soon discovered how tenacious these birds were of life. When in
the evening pluming themselves in a flock, they make the same
odd mixture of sounds which bull-frogs do within the tropics.
In Tierra del Fuego, as well as in the Falkland Islands,
made many observations on the lower marine animals, [11] but
they are of little general interest. I will mention only one
class of facts, relating to certain zoophytes in the more highly
organized division of that class. Several genera (Flustra,
Eschara, Cellaria, Crisia, and others) agree in having singular
moveable organs (like those of Flustra avicularia, found
in the European seas) attached to their cells. The organ, in
the greater number of cases, very closely resembles the head
of a vulture; but the lower mandible can be opened much
wider than in a real bird's beak. The head itself possessed
considerable powers of movement, by means of a short neck.
In one zoophyte the head itself was fixed, but the lower jaw
free: in another it was replaced by a triangular hood, with
beautifully-fitted trap-door, which evidently answered to the
lower mandible. In the greater number of species, each cell
was provided with one head, but in others each cell had two.
The young cells at the end of the branches of these corallines
contain quite immature polypi, yet the vulture-head
attached to them, though small, are in every respect perfect
When the polypus was removed by a needle from any of the
cells, these organs did not appear in the least affected. When
one of the vulture-like heads was cut off from the cell, the
lower mandible retained its power of opening and closing.
Perhaps the most singular part of their structure is, that
when there were more than two rows of cells on a branch,
the central cells were furnished with these appendages, of
only one-fourth the size of the outside ones. Their movements
varied according to the species; but in some I never
saw the least motion; while others, with the lower mandible
generally wide open, oscillated backwards and forwards at
the rate of about five seconds each turn, others moved rapidly
and by starts. When touched with a needle, the beak
generally seized the point so firmly, that the whole branch
might be shaken.
These bodies have no relation whatever with the production
of the eggs or gemmules, as they are formed before the
young polypi appear in the cells at the end of the growing
branches; as they move independently of the polypi, and do
not appear to be in any way connected with them; and as
they differ in size on the outer and inner rows of cells, I have
little doubt, that in their functions, they are related rather
to the horny axis of the branches than to the polypi in the
cells. The fleshy appendage at the lower extremity of the
sea-pen (described at Bahia Blanca) also forms part of the
zoophyte, as a whole, in the same manner as the roots of a
tree form part of the whole tree, and not of the individual
leaf or flower-buds.
In another elegant little coralline (Crisia?), each cell was
furnished with a long-toothed bristle, which had the power
of moving quickly. Each of these bristles and each of the
vulture-like heads generally moved quite independently of
the others, but sometimes all on both sides of a branch,
sometimes only those on one side, moved together
coinstantaneously, sometimes each moved in regular order one
after another. In these actions we apparently behold as perfect
a transmission of will in the zoophyte, though composed of
thousands of distinct polypi, as in any single animal. The
case, indeed, is not different from that of the sea-pens, which,
when touched, drew themselves into the sand on the coast of
Bahia Blanca. I will state one other instance of uniform
action, though of a very different nature, in a zoophyte
closely allied to Clytia, and therefore very simply organized.
Having kept a large tuft of it in a basin of salt-water, when
it was dark I found that as often as I rubbed any part of a
branch, the whole became strongly phosphorescent with a
green light: I do not think I ever saw any object more
beautifully so. But the remarkable circumstance was, that the
flashes of light always proceeded up the branches, from the
base towards the extremities.
The examination of these compound animals was always
very interesting to me. What can be more remarkable that
to see a plant-like body producing an egg, capable of swimming
about and of choosing a proper place to adhere to,
which then sprouts into branches, each crowded with innumerable
distinct animals, often of complicated organizations.
The branches, moreover, as we have just seen, sometimes
possess organs capable of movement and independent of the
polypi. Surprising as this union of separate individuals in
common stock must always appear, every tree displays the
same fact, for buds must be considered as individual plants.
It is, however, natural to consider a polypus, furnished with
a mouth, intestines, and other organs, as a distinct individual,
whereas the individuality of a leaf-bud is not easily realised,
so that the union of separate individuals in a common body
is more striking in a coralline than in a tree. Our conception
of a compound animal, where in some respects the individuality
of each is not completed, may be aided, by reflecting
on the production of two distinct creatures by bisecting a
single one with a knife, or where Nature herself performs
the task of bisection.
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