While some parts of the floor of the abysses are more thickly peopled
than others, there is no depth limit to the distribution of life.
Wherever the long arm of the dredge has reached, animals have been
found, e.g. Protozoa, sponges, corals, worms, starfishes, sea-urchins,
sea-lilies, crustaceans, lamp-shells, molluscs, ascidians, and fishes--a
very representative fauna. In the absence of light there can be no
chlorophyll-possessing plants, and as the animals cannot all be eating
one another there must be an extraneous source of food-supply. This is
found in the sinking down of minute organisms which are killed on the
surface by changes of temperature and other causes. What is left of
them, before or after being swallowed, and of sea-dust and mineral
particles of various kinds forms the diversified "ooze" of the
sea-floor, a soft muddy precipitate, which is said to have in places the
consistence of butter in summer weather.
There seems to be no bacteria in the abysses, so there can be no
rotting. Everything that sinks down, even the huge carcase of a whale,
must be nibbled away by hungry animals and digested, or else, in the
case of most bones, slowly dissolved away. Of the whale there are left
only the ear-bones, of the shark his teeth.