In One Day We Passed Through Two Spaces Of
Water Thus Stained, One Of Which Alone Must Have Extended
Over Several Square Miles.
What incalculable numbers of
these microscopical animals!
The colour of the water, as
seen at some distance, was like that of a river which has
flowed through a red clay district, but under the shade of
the vessel's side it was quite as dark as chocolate. The line
where the red and blue water joined was distinctly defined.
The weather for some days previously had been calm, and the
ocean abounded, to an unusual degree, with living creatures. [9]
In the sea around Tierra del Fuego, and at no great distance
from the land, I have seen narrow lines of water of a
bright red colour, from the number of crustacea, which
somewhat resemble in form large prawns. The sealers call
them whale-food. Whether whales feed on them I do not
know; but terns, cormorants, and immense herds of great
unwieldy seals derive, on some parts of the coast, their
chief sustenance from these swimming crabs. Seamen
invariably attribute the discoloration of the water to spawn;
but I found this to be the case only on one occasion. At
the distance of several leagues from the Archipelago of the
Galapagos, the ship sailed through three strips of a dark
yellowish, or mud-like water; these strips were some miles
long, but only a few yards wide, and they were separated
from the surrounding water by a sinuous yet distinct margin.
The colour was caused by little gelatinous balls, about
the fifth of an inch in diameter, in which numerous minute
spherical ovules were imbedded: they were of two distinct
kinds, one being of a reddish colour and of a different shape
from the other. I cannot form a conjecture as to what two
kinds of animals these belonged. Captain Colnett remarks,
that this appearance is very common among the Galapagos
Islands, and that the directions of the bands indicate that
of the currents; in the described case, however, the line was
caused by the wind. The only other appearance which I
have to notice, is a thin oily coat on the water which displays
iridescent colours. I saw a considerable tract of the
ocean thus covered on the coast of Brazil; the seamen
attributed it to the putrefying carcase of some whale, which
probably was floating at no great distance. I do not here
mention the minute gelatinous particles, hereafter to be
referred to, which are frequently dispersed throughout the
water, for they are not sufficiently abundant to create any
change of colour.
There are two circumstances in the above accounts which
appear remarkable: first, how do the various bodies which
form the bands with defined edges keep together? In the
case of the prawn-like crabs, their movements were as
co-instantaneous as in a regiment of soldiers; but this cannot
happen from anything like voluntary action with the ovules,
or the confervae, nor is it probable among the infusoria.
Secondly, what causes the length and narrowness of the
bands?
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