With a span of more than double the size
of landmass, the waterworld has always been a source of myriads of life
Obviously it is in this water world where the first forms of animal life made their
appearance. It was long long before they appeared on land. In that sense water world
is an older habitat of animals than land. Like land, the geosphere of the waterworld
comprising the hydrosphere and the bed below is not uniform. For instance, the depth
of the water varies from a few feet at the shore to thousands of feet deep at
some parts of the deep seas. There are even places the depth of which goes
much more than the world's highest mountain peaks. With such a varying
depth the surface of the water bed is also randomly uneven. From comparatively plain
basins the surface of the bed, or the topography, diversifies into hills,
mountain ranges, valleys, craters and some abysmal trenches.
Quite in line with the land, the temperature of the waterworld also varies from
warm to freezing cold. Naturally such a variety has helped quite a large
number of life forms to throng this part of the world and find a suitable
habitat for each of them.
The once mysteries of the vast waterworld have been unveiled a long while
back. Series of explorations under the water and at the bottom of the seas and
oceans has enlightened us about myriads of plants and animals which have made
water their home. Today we know, there is no less variety of marine creatures
than that of the land animals. The size and shapes may be different. Yet they
have a world no less fascinating than the one above.
Like those on the surface, life under water also needs oxygen and some
sunlight. Oxygen apart, these creatures also need mineral salts dissolved
in water. And the water contains oxygen. It is also rich in common salt. But in
places the other salts that the sea plants and animals must have are scarce. This is
particularly so in warm oceans, where a thin, warm surface layer of water
floats upon a thick, cold layer. Because the layers do not mix, salts from deep down
cannot rise to take the place of those above used up by plants and animals.
Thus warm oceans usually cannot feed as many living things as cool water
can. Thus, like the life on the surface, water world offers different
habitats for different variety of animals.
Most marine plants and animals live in the upper sunlit layers of the sea. Here grow
the small drifting algae - the green plants that furnish food for tiny drifting
animals. These animals provide nourishment for small fishes that larger fishes eat.
Deep down it is too dark for plants to grow. It's also colder there. But there
are fishes and other animals that feed on the rain of dead and dying
creatures falling from the above. These creatures find no difficulty in living
the way down with an adaptive mechanism to face a different surrounding.
In the open ocean, plants and animals simply ride the storm waves. But life is
tougher at the sea's edge. Waves pound the shore. Most shores suffer twice daily
drying out and soaking from the tides. They are also more open to attack from heat
and cold than creatures of the open ocean.
Let us start our journey to the deep starting from the shores.
the shore liners |the sea world |the freshwater