In a 1983 paper, the oceanographer Tony Rice offers an
explanation for the appearance of Bathybius
haeckelii, thought to have been a living organism by T.H.Huxley [1]. Rice
writes [2]:
In the 100 years or so since
Huxley's Bathybius was relegated to
the status of an interesting but embarrassing error, knowledge of deep-sea
biology has increased enormously, for many thousands of samples both from
mid-water and from the deep-sea floor have been collected and examined. Consequently,
although the deep ocean is still the least well-understood environment on earth
because of its relative inaccessibility, some basic facts about its biological processes
are now well-established...
.. With the exception of the minor
local input from the activities of chemo-autotrophic bacteria, the food supply
on which all deep sea animals are ultimately dependent originates in the near surface
layers. In temperate waters, at least, the surface productivity is very
seasonal, being highest in spring and summer when the phytoplankton is growing
rapidly, and very low during the winter months. Although some of this material
reaches the sea floor in the form of large, fast-sinking carcasses of fishes
and whales, the main supply probably arrives as small particles, including the
bodies of small plants and animals and faecal pellets, which may take many
weeks to sink through the water column.
We now know that the sinking material also contains large
numbers of flocs and other aggregates bound by the exudates of both bacteria
and algae [3]. It is these that give the appearance of fluff that can be found
over the ocean floor and which are difficult to collect in dredges, but which
are clearly visible in sediment traps [2].
All this is a bit technical.
In the simplest terms, what Huxley observed was a large floc
that contained components from near-surface organisms; the conclusion of
contemporary scientists being that it was a precipitate of calcium sulphate, caused
by preservation of a sample of sea bed in alcohol. This put an end to questions about the organic matter that was also
present and the our seeming need to focus on organisms, rather than on total organic
matter, was also a problem. We continue this focus, rather than taking the
whole package of living and dead organic matter into account.
Let me give an example. What do you see when you look at
this image from NOAA [4]?
Most will see an interesting creature – a whiplash squid
– and wonder about its biology and mode of life. What about all the white dots
in the rest of the picture, illuminated like the particles visible in the beam of a cinema
projector? Don't these raise questions?
While we know more about these particles and aggregates than
we did when Tony Rice wrote his article, we still tend to ignore them in favour
of our interest in organisms. It is true that the organic matter present in oceans, and other
water bodies, is largely dependent on organisms for its production [3], but we
must always consider the whole organic, and inorganic, package when trying to understand
the biology of water bodies. What a pity that way of thinking didn't start with
Huxley's observations on Bathybius.
[2] A.L.Rice (1983) Thomas Henry Huxley and the strange case
of Bathybius haeckelii; a possible alternative
explanation. Archives of Natural History
11:169-180.
[3] Roger S. Wotton (2005) The essential role of exopolymers
(EPS) in aquatic systems. Oceanography
and Marine Biology: An Annual Review 42:57-94.
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